ACETIC ACID

ACETIC ACID (ASETK AST)

CAS No. : 64-19-7

EC No. : 200-580-7

Synonyms:

Acetic acid ; Asetik asit ; Glasiyal , Asetikasit ; Aseticacid ; asetic acid ; asetik acid ; acetik asit ; ethonik asit , etonik asit ; ethonic asit ; etonik acid ; glacial acid , glasiyal acid ; asetik asit glasiyal ; metan karboksilik asit ; methanekarboksilik asit ; methanecarbocsilic acid ;methycarbocsilic acid ;

Acetic Acid Glacial; ACETIC ACID, GLACIAL; Acide acetique; acido acetico, de una concentracion superior al 10 por ciento, en peso, de acido acetico ; Aci-Jel; E 260; ESSIGSAEURE UEBER 10 BIS 40%; ESSIGSAEURE UEBER 40%; Essigsaure; Ethanoic acid; Ethanoic acid monomer; Ethylic acid; Glacial acetic acid; Methanecarboxylic acid; Vinegar acid Vinegar (when dilute); Hydrogen acetate; Methanecarboxylic acid Ethanoic acid ; Acetic acid (aqueous), Ethanoic acid, Glacial acetic acid (pure compound), Methanecarboxylic acid ; Acetic acid; Ethanoic acid; Ethylic acid; Methanecarboxylic acid; Glacial acetic acid; Vinegar acid Acetic acid, methane carboxylic acid; ethanoic acid ; 200-580-7 64-19-7 Acetic acid Acid, Acetic; Acide actique Acido acetico ttiksyra azido azetikoa azijnzuur CH3CO2H CH3COOH Essigsure Ethanoic acid; etikkahappo Glacial acetic acid; EINECS 200-580-7; MeCO2H MeCOOH Methanecarboxylic acid; methyl carboxylic acid; MFCD00036152; MFCD00036287; Molybdic acid Octan barnaty Octowy kwas Octowy kwas; Pyroacetic acid; PYROACETIC ETHER; IODINE CHLORIDE; IODINE MONOCHLORIDE; IODINE MONOCHLORIDE SOLUTION, WIJS; IODINE-MONOCHLORIDE, WIJS; IODINE SOLUTION ACCORDING TO WIJS; IODOCHLORIDE; IODOMONOCHLORIDE; WIJ`S IODINE SOLUTION; WIJS` REAGENT; Acetasol; aceticacid(non-specificname); aceticacid(solutionsgreaterthan10%) ; Glacial acetic acid ; Ethanoic acid ; Ethylic acid ;Acetic acid ; Asetik asit ; Glasiyal , Asetikasit ; Aseticacid ; asetic acid ; asetik acid ; acetik asit ; ethonik asit , etonik asit ; ethonic asit ; etonik acid ; glacial acid , glasiyal acid ; asetik asit glasiyal ; metan karboksilik asit ; methanekarboksilik asit ; methanecarbocsilic acid ;methycarbocsilic acid ; Acetic Acid Glacial; ACETIC ACID, GLACIAL; Acide acetique; acido acetico, de una concentracion superior al 10 por ciento, en peso, de acido acetico ; Aci-Jel; E 260; ESSIGSAEURE UEBER 10 BIS 40%; ESSIGSAEURE UEBER 40%; Essigsaure; Ethanoic acid; Ethanoic acid monomer; Ethylic acid; Glacial acetic acid; Methanecarboxylic acid; Vinegar acid Vinegar (when dilute); Hydrogen acetate; Methanecarboxylic acid Ethanoic acid ; Acetic acid (aqueous), Ethanoic acid, Glacial acetic acid (pure compound), Methanecarboxylic acid ; Acetic acid; Ethanoic acid; Ethylic acid; Methanecarboxylic acid; Glacial acetic acid; Vinegar acid Acetic acid, methane carboxylic acid; ethanoic acid ; 200-580-7 64-19-7 Acetic acid Acid, Acetic; Acide actique Acido acetico ttiksyra azido azetikoa azijnzuur CH3CO2H CH3COOH Essigsure Ethanoic acid; etikkahappo Glacial acetic acid; EINECS 200-580-7; MeCO2H MeCOOH Methanecarboxylic acid; methyl carboxylic acid; MFCD00036152; MFCD00036287; Molybdic acid Octan barnaty Octowy kwas Octowy kwas; Pyroacetic acid; PYROACETIC ETHER; IODINE CHLORIDE; IODINE MONOCHLORIDE; IODINE MONOCHLORIDE SOLUTION, WIJS; IODINE-MONOCHLORIDE, WIJS; IODINE SOLUTION ACCORDING TO WIJS; IODOCHLORIDE; IODOMONOCHLORIDE; WIJ`S IODINE SOLUTION; WIJS` REAGENT; Acetasol; aceticacid(non-specificname); aceticacid(solutionsgreaterthan10%) ; Glacial acetic acid ; Ethanoic acid ; Ethylic acid ; Methanecarboxylic acid ; Glacial acetic acid; Acetic acid solution; acetic acid 50%; acetic acid, of a concentration of more than 10 per cent, by weight, of acetic acid; Acetic Acid Glacial BP; Natural Acetic Acid; Acetic acid (36%); Acetic acid,food grade; Acetic Acid Glacial; GAA; Acetic Acid, Glacial; Asetik asit; Acide acetique; Acetic Acid; Acetic Acid; Acetik Acit; Asetik acit; asetik acide; acetik asid; asetic acid; asetic acide; Asetikasit; Asetique asit; Acideacetique; AceticAcid; ASETK AST; ACDE ACETQUE; ACETC ACD; ACETC ACD; ACETK ACT; ASETK ACT; ASETK ACDE; ACETK ASD; ASETC ACD; ASETC ACDE; ASETKAST; ASETQUE AST; ACDEACETQUE; ACETCACD; asetik asit; acide acetique; acetic acid; acetic acid; acetik acit; asetik acit; asetik acide; acetik asid; asetic acid; asetic acide; asetikasit; asetique asit; acideacetique; Methanecarboxylic acid ; Glacial acetic acid; Acetic acid solution; acetic acid 50%; acetic acid, of a concentration of more than 10 per cent, by weight, of acetic acid; Acetic Acid Glacial BP; Natural Acetic Acid; Acetic acid (36%); Acetic acid,food grade; Acetic Acid Glacial; GAA; Acetic Acid, Glacial; Asetik asit; Acide acetique; Acetic Acid; Acetic Acid; Acetik Acit; Asetik acit; asetik acide; acetik asid; asetic acid; asetic acide; Asetikasit; Asetique asit; Acideacetique; AceticAcid; ASETK AST; ACDE ACETQUE; ACETC ACD; ACETC ACD; ACETK ACT; ASETK ACT; ASETK ACDE; ACETK ASD; ASETC ACD; ASETC ACDE; ASETKAST; ASETQUE AST; ACDEACETQUE; ACETCACD; asetik asit; acide acetique; acetic acid; acetic acid; acetik acit; asetik acit; asetik acide; acetik asid; asetic acid; asetic acide; asetikasit; asetique asit; acideacetique; aceticacid; Asetik Asit; Acide Acetique; Acetic Acid; Acetic Acid; Acetik Acit; Asetik Acit; Asetik Acide; Acetik Asid; Asetic Acid; Asetic Acide; Asetikasit; Asetique Asit; Acideacetique; Aceticacid

ACETIC ACID

Overview

Description

Product Information

Applications

Physicochemical Information

Toxicological Information

Safety Information according to GHS

Safety Information

Storage and Shipping Information

Transport Information

Specifications

Key Spec Table

Pricing & Availability

Key Spec Table

CAS # EC Number Hill Formula Chemical Formula Molar Mass

64-19-7 200-580-7 C₂H₄O₂ CH₃COOH 60.05 g/mol

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Description

Catalogue Number 818755

Synonyms Ethanoic acid

Product Information

CAS number 64-19-7

EC index number 607-002-00-6

EC number 200-580-7

Hill Formula C₂H₄O₂

Chemical formula CH₃COOH

Molar Mass 60.05 g/mol

HS Code 2915 21 00

Structure formula Image Structure formula Image

Quality Level MQ200

Applications

Application Acetic acid 99-100% for synthesis. CAS No. 64-19-7, EC Number 200-580-7.

Physicochemical Information

Boiling point 116 – 118 C (1013 hPa)

Density 1.05 g/cm3 (20 C)

Explosion limit 4 – 19.9 %(V)

Flash point 40 C

Ignition temperature 485 C

Melting Point 17 C

pH value 2.5 (50 g/l, H₂O, 20 C)

Vapor pressure 15.4 hPa (20 C)

Viscosity kinematic 1.17 mm2/s (20 C)

Solubility 602.9 g/l soluble

Acetic Acid is a synthetic carboxylic acid with antibacterial and antifungal properties. Although its mechanism of action is not fully known, undissociated acetic acid may enhance lipid solubility allowing increased fatty acid accumulation on the cell membrane or in other cell wall structures. Acetic acid, as a weak acid, can inhibit carbohydrate metabolism resulting in subsequent death of the organism.

NCI Thesaurus (NCIt)

Acetic acid is one of the simplest carboxylic acids. It is an important chemical reagent and industrial chemical that is used in the production of plastic soft drink bottles, photographic film; and polyvinyl acetate for wood glue, as well as many synthetic fibres and fabrics. In households diluted acetic acid is often used as a cleaning agent. In the food industry acetic acid is used as an acidity regulator. The acetyl group, derived from acetic acid, is fundamental to the biochemistry of virtually all forms of life. When bound to coenzyme A it is central to the metabolism of carbohydrates and fats. However, the concentration of free acetic acid in cells is kept at a low level to avoid disrupting the control of the pH of the cell contents. Acetic acid is produced and excreted by certain bacteria, notably the Acetobacter genus and Clostridium acetobutylicum. These bacteria are found universally in foodstuffs, water, and soil, and acetic acid is produced naturally as fruits and some other foods spoil. Acetic acid is also a component of the vaginal lubrication of humans and other primates, where it appears to serve as a mild antibacterial agent. Acetic acid is found to be associated with phenylketonuria, which is an inborn error of metabolism.

Human Metabolome Database (HMDB)

Acetic acid is a simple monocarboxylic acid containing two carbons. It has a role as a protic solvent, a food acidity regulator, an antimicrobial food preservative and a Daphnia magna metabolite. It is a conjugate acid of an acetate.

Acetic acid /əˈsiːtɪk/, systematically named ethanoic acid /ˌɛθəˈnoʊɪk/, is a colourless liquid organic compound with the chemical formula CH3COOH (also written as CH3CO2H, C2H4O2, or HC2H3O2). When undiluted, it is sometimes called glacial acetic acid. Vinegar is no less than 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. Acetic acid has a distinctive sour taste and pungent smell. In addition to household vinegar, it is mainly produced as a precursor to polyvinyl acetate and cellulose acetate. It is classified as a weak acid since it only partially dissociates in solution, but concentrated acetic acid is corrosive and can attack the skin.

Acetic acid is the second simplest carboxylic acid (after formic acid). It consists of a methyl group attached to a carboxyl group. It is an important chemical reagent and industrial chemical, used primarily in the production of cellulose acetate for photographic film, polyvinyl acetate for wood glue, and synthetic fibres and fabrics. In households, diluted acetic acid is often used in descaling agents. In the food industry, acetic acid is controlled by the food additive code E260 as an acidity regulator and as a condiment. In biochemistry, the acetyl group, derived from acetic acid, is fundamental to all forms of life. When bound to coenzyme A, it is central to the metabolism of carbohydrates and fats.

The global demand for acetic acid is about 6.5 million metric tons per year (Mt/a), of which approximately 1.5 Mt/a is met by recycling; the remainder is manufactured from methanol.[9] Vinegar is mostly dilute acetic acid, often produced by fermentation and subsequent oxidation of ethanol.

Nomenclature

The trivial name acetic acid is the most commonly used and preferred IUPAC name. The systematic name ethanoic acid, a valid IUPAC name, is constructed according to the substitutive nomenclature.[10] The name acetic acid derives from acetum, the Latin word for vinegar, and is related to the word acid itself.

Glacial acetic acid is a name for water-free (anhydrous) acetic acid. Similar to the German name Eisessig (ice vinegar), the name comes from the ice-like crystals that form slightly below room temperature at 16.6 C (61.9 F) (the presence of 0.1% water lowers its melting point by 0.2 C).[11]

A common symbol for acetic acid is AcOH, where Ac is the pseudoelement symbol representing the acetyl group CH

3-C(=O)-; the conjugate base, acetate (CH

3COO-), is thus represented as AcO-.[12] (The Ac is not to be confused with the symbol for the element actinium; the context prevents confusion among organic chemists). To better reflect its structure, acetic acid is often written as CH

3-C(O)OH, CH

3-C(=O)OH, CH

3COOH, and CH

3CO

2H. In the context of acid-base reactions, the abbreviation HAc is sometimes used,[13] where Ac in this case is a symbol for acetate (rather than acetyl). Acetate is the ion resulting from loss of H+

from acetic acid. The name acetate can also refer to a salt containing this anion, or an ester of acetic acid.[14]

Properties

Acetic acid crystals

Acidity

The hydrogen centre in the carboxyl group (-COOH) in carboxylic acids such as acetic acid can separate from the molecule by ionization:

CH3COOH ⇌ CH3CO2- + H+

Because of this release of the proton (H+), acetic acid has acidic character. Acetic acid is a weak monoprotic acid. In aqueous solution, it has a pKa value of 4.76.[15] Its conjugate base is acetate (CH3COO-). A 1.0 M solution (about the concentration of domestic vinegar) has a pH of 2.4, indicating that merely 0.4% of the acetic acid molecules are dissociated.[16] However, in very dilute (90% dissociated.

Deprotonation equilibrium of acetic acid in water

Cyclic dimer of acetic acid; dashed green lines represent hydrogen bonds

Structure

In solid acetic acid, the molecules form chains, individual molecules being interconnected by hydrogen bonds.[17] In the vapour at 120 C (248 F), dimers can be detected. Dimers also occur in the liquid phase in dilute solutions in non-hydrogen-bonding solvents, and a certain extent in pure acetic acid,[18] but are disrupted by hydrogen-bonding solvents. The dissociation enthalpy of the dimer is estimated at 65.0-66.0 kJ/mol, and the dissociation entropy at 154-157 J mol-1 K-1.[19] Other carboxylic acids engage in similar intermolecular hydrogen bonding interactions.[20]

Solvent properties

Liquid acetic acid is a hydrophilic (polar) protic solvent, similar to ethanol and water. With a moderate relative static permittivity (dielectric constant) of 6.2, it dissolves not only polar compounds such as inorganic salts and sugars, but also non-polar compounds such as oils as well as polar solutes. It is miscible with polar and non-polar solvents such as water, chloroform, and hexane. With higher alkanes (starting with octane), acetic acid is not miscible at all compositions, and solubility of acetic acid in alkanes declines with longer n-alkanes.[21] The solvent and miscibility properties of acetic acid make it a useful industrial chemical, for example, as a solvent in the production of dimethyl terephthalate.[9]

Biochemistry

At physiological pHs, acetic acid is usually fully ionised to acetate.

The acetyl group, formally derived from acetic acid, is fundamental to all forms of life. When bound to coenzyme A, it is central to the metabolism of carbohydrates and fats. Unlike longer-chain carboxylic acids (the fatty acids), acetic acid does not occur in natural triglycerides. However, the artificial triglyceride triacetin (glycerine triacetate) is a common food additive and is found in cosmetics and topical medicines.[22]

Acetic acid is produced and excreted by acetic acid bacteria, notably the genus Acetobacter and Clostridium acetobutylicum. These bacteria are found universally in foodstuffs, water, and soil, and acetic acid is produced naturally as fruits and other foods spoil. Acetic acid is also a component of the vaginal lubrication of humans and other primates, where it appears to serve as a mild antibacterial agent.[23]

Production

Purification and concentration plant for acetic acid in 1884

Acetic acid is produced industrially both synthetically and by bacterial fermentation. About 75% of acetic acid made for use in the chemical industry is made by the carbonylation of methanol, explained below.[9] The biological route accounts for only about 10% of world production, but it remains important for the production of vinegar because many food purity laws require vinegar used in foods to be of biological origin. Other processes are methyl formate isomerization, conversion of syngas to acetic acid, and gas phase oxidation of ethylene and ethanol.[24] Acetic acid is often a side product of different reactions, i.e. during heterogeneous catalytic acrylic acid synthesis[25][26][27] or fermentative lactic acid production.[28] As of 2003-2005, total worldwide production of virgin acetic acid[29] was estimated at 5 Mt/a (million tonnes per year), approximately half of which was produced in the United States. European production was approximately 1 Mt/a and declining, while Japanese production was 0.7 Mt/a. Another 1.5 Mt were recycled each year, bringing the total world market to 6.5 Mt/a.[30][31] Since then the global production has increased to 10.7 Mt/a (in 2010), and further; however, a slowing in this increase in production is predicted.[32] The two biggest producers of virgin acetic acid are Celanese and BP Chemicals. Other major producers include Millennium Chemicals, Sterling Chemicals, Samsung, Eastman, and Svensk Etanolkemi.[33]

Methanol carbonylation

Most acetic acid is produced by methanol carbonylation. In this process, methanol and carbon monoxide react to produce acetic acid according to the equation:

Methanol formylation.png

The process involves iodomethane as an intermediate, and occurs in three steps. A catalyst, metal carbonyl, is needed for the carbonylation (step 2).[34]

CH3OH + HI → CH3I + H2O

CH3I + CO → CH3COI

CH3COI + H2O → CH3COOH + HI

Two related processes for the carbonylation of methanol: the rhodium-catalyzed Monsanto process, and the iridium-catalyzed Cativa process. The latter process is greener and more efficient[35] and has largely supplanted the former process, often in the same production plants. Catalytic amounts of water are used in both processes, but the Cativa process requires less, so the water-gas shift reaction is suppressed, and fewer by-products are formed.

By altering the process conditions, acetic anhydride may also be produced on the same plant using the rhodium catalysts.[36]

Acetaldehyde oxidation

Prior to the commercialization of the Monsanto process, most acetic acid was produced by oxidation of acetaldehyde. This remains the second-most-important manufacturing method, although it is usually not competitive with the carbonylation of methanol. The acetaldehyde can be produced by hydration of acetylene. This was the dominant technology in the early 1900s.[37]

Light naphtha components are readily oxidized by oxygen or even air to give peroxides, which decompose to produce acetic acid according to the chemical equation, illustrated with butane:

2 C4H10 + 5 O2 → 4 CH3CO2H + 2 H2O

Such oxidations require metal catalyst, such as the naphthenate salts of manganese, cobalt, and chromium.

The typical reaction is conducted at temperatures and pressures designed to be as hot as possible while still keeping the butane a liquid. Typical reaction conditions are 150 C (302 F) and 55 atm.[38] Side-products may also form, including butanone, ethyl acetate, formic acid, and propionic acid. These side-products are also commercially valuable, and the reaction conditions may be altered to produce more of them where needed. However, the separation of acetic acid from these by-products adds to the cost of the process.[39]

Under similar conditions and using similar catalysts as are used for butane oxidation, the oxygen in air to produce acetic acid can oxidize acetaldehyde.[39]

2 CH3CHO + O2 → 2 CH3CO2H

Using modern catalysts, this reaction can have an acetic acid yield greater than 95%. The major side-products are ethyl acetate, formic acid, and formaldehyde, all of which have lower boiling points than acetic acid and are readily separated by distillation.[39]

Ethylene oxidation

Acetaldehyde may be prepared from ethylene via the Wacker process, and then oxidised as above.

In more recent times, chemical company Showa Denko, which opened an ethylene oxidation plant in Ōita, Japan, in 1997, commercialised a cheaper single-stage conversion of ethylene to acetic acid.[40] The process is catalyzed by a palladium metal catalyst supported on a heteropoly acid such as silicotungstic acid. Similar process use the same metal catalyst on silicotungstic acid and silica:[41]

C2H4 + O2 → CH3CO2H

It is thought to be competitive with methanol carbonylation for smaller plants (100-250 kt/a), depending on the local price of ethylene. The approach will be based on utilizing a novel selective photocatalytic oxidation technology for the selective oxidation of ethylene and ethane to acetic acid. Unlike traditional oxidation catalysts, the selective oxidation process will use UV light to produce acetic acid at ambient temperatures and pressure.

Oxidative fermentation

For most of human history, acetic acid bacteria of the genus Acetobacter have made acetic acid, in the form of vinegar. Given sufficient oxygen, these bacteria can produce vinegar from a variety of alcoholic foodstuffs. Commonly used feeds include apple cider, wine, and fermented grain, malt, rice, or potato mashes. The overall chemical reaction facilitated by these bacteria is:

C2H5OH + O2 → CH3COOH + H2O

A dilute alcohol solution inoculated with Acetobacter and kept in a warm, airy place will become vinegar over the course of a few months. Industrial vinegar-making methods accelerate this process by improving the supply of oxygen to the bacteria.[42]

The first batches of vinegar produced by fermentation probably followed errors in the winemaking process. If must is fermented at too high a temperature, acetobacter will overwhelm the yeast naturally occurring on the grapes. As the demand for vinegar for culinary, medical, and sanitary purposes increased, vintners quickly learned to use other organic materials to produce vinegar in the hot summer months before the grapes were ripe and ready for processing into wine. This method was slow, however, and not always successful, as the vintners did not understand the process.[43]

One of the first modern commercial processes was the “fast method” or “German method”, first practised in Germany in 1823. In this process, fermentation takes place in a tower packed with wood shavings or charcoal. The alcohol-containing feed is trickled into the top of the tower, and fresh air supplied from the bottom by either natural or forced convection. The improved air supply in this process cut the time to prepare vinegar from months to weeks.[44]

Nowadays, most vinegar is made in submerged tank culture, first described in 1949 by Otto Hromatka and Heinrich Ebner.[45] In this method, alcohol is fermented to vinegar in a continuously stirred tank, and oxygen is supplied by bubbling air through the solution. Using modern applications of this method, vinegar of 15% acetic acid can be prepared in only 24 hours in batch process, even 20% in 60-hour fed-batch process.[43]

Anaerobic fermentation

Species of anaerobic bacteria, including members of the genus Clostridium or Acetobacterium can convert sugars to acetic acid directly without creating ethanol as an intermediate. The overall chemical reaction conducted by these bacteria may be represented as:

C6H12O6 → 3 CH3COOH

These acetogenic bacteria produce acetic acid from one-carbon compounds, including methanol, carbon monoxide, or a mixture of carbon dioxide and hydrogen:

2 CO2 + 4 H2 → CH3COOH + 2 H2O

This ability of Clostridium to metabolize sugars directly, or to produce acetic acid from less costly inputs, suggests that these bacteria could produce acetic acid more efficiently than ethanol-oxidizers like Acetobacter. However, Clostridium bacteria are less acid-tolerant than Acetobacter. Even the most acid-tolerant Clostridium strains can produce vinegar in concentrations of only a few per cent, compared to Acetobacter strains that can produce vinegar in concentrations up to 20%. At present, it remains more cost-effective to produce vinegar using Acetobacter, rather than using Clostridium and concentrating it. As a result, although acetogenic bacteria have been known since 1940, their industrial use is confined to a few niche applications.[46]

Uses

Acetic acid is a chemical reagent for the production of chemical compounds. The largest single use of acetic acid is in the production of vinyl acetate monomer, closely followed by acetic anhydride and ester production. The volume of acetic acid used in vinegar is comparatively small.[9][31]

Vinyl acetate monomer

The primary use of acetic acid is the production of vinyl acetate monomer (VAM). In 2008, this application was estimated to consume a third of the world`s production of acetic acid.[9] The reaction consists of ethylene and acetic acid with oxygen over a palladium catalyst, conducted in the gas phase.[47]

2 H3C-COOH + 2 C2H4 + O2 → 2 H3C-CO-O-CH=CH2 + 2 H2O

Vinyl acetate can be polymerised to polyvinyl acetate or other polymers, which are components in paints and adhesives.[47]

Ester production

The major esters of acetic acid are commonly used as solvents for inks, paints and coatings. The esters include ethyl acetate, n-butyl acetate, isobutyl acetate, and propyl acetate. They are typically produced by catalyzed reaction from acetic acid and the corresponding alcohol:

H3C-COOH + HO-R → H3C-CO-O-R + H2O, (R = a general alkyl group)

Most acetate esters, however, are produced from acetaldehyde using the Tishchenko reaction. In addition, ether acetates are used as solvents for nitrocellulose, acrylic lacquers, varnish removers, and wood stains. First, glycol monoethers are produced from ethylene oxide or propylene oxide with alcohol, which are then esterified with acetic acid. The three major products are ethylene glycol monoethyl ether acetate (EEA), ethylene glycol monobutyl ether acetate (EBA), and propylene glycol monomethyl ether acetate (PMA, more commonly known as PGMEA in semiconductor manufacturing processes, where it is used as a resist solvent). This application consumes about 15% to 20% of worldwide acetic acid. Ether acetates, for example EEA, have been shown to be harmful to human reproduction.[31]

Acetic anhydride

The product of the condensation of two molecules of acetic acid is acetic anhydride. The worldwide production of acetic anhydride is a major application, and uses approximately 25% to 30% of the global production of acetic acid. The main process involves dehydration of acetic acid to give ketene at 700-750 C. Ketene is thereafter reacted with acetic acid to obtain the anhydride:[48]

CH3CO2H → CH2=C=O + H2O

CH3CO2H + CH2=C=O → (CH3CO)2O

Acetic anhydride is an acetylation agent. As such, its major application is for cellulose acetate, a synthetic textile also used for photographic film. Acetic anhydride is also a reagent for the production of heroin and other compounds.[48]

Use as solvent

Glacial acetic acid is an excellent polar protic solvent, as noted above. It is frequently used as a solvent for recrystallization to purify organic compounds. Acetic acid is used as a solvent in the production of terephthalic acid (TPA), the raw material for polyethylene terephthalate (PET). In 2006, about 20% of acetic acid was used for TPA production.[31]

Acetic acid is often used as a solvent for reactions involving carbocations, such as Friedel-Crafts alkylation. For example, one stage in the commercial manufacture of synthetic camphor involves a Wagner-Meerwein rearrangement of camphene to isobornyl acetate; here acetic acid acts both as a solvent and as a nucleophile to trap the rearranged carbocation.[49]

Glacial acetic acid is used in analytical chemistry for the estimation of weakly alkaline substances such as organic amides. Glacial acetic acid is a much weaker base than water, so the amide behaves as a strong base in this medium. It then can be titrated using a solution in glacial acetic acid of a very strong acid, such as perchloric acid.[50]

Medical use

Main article: Acetic acid (medical use)

Acetic acid injection into a tumor has been used to treat cancer since the 1800s.[51][52]

Acetic acid is used as part of cervical cancer screening in many areas in the developing world.[53] The acid is applied to the cervix and if an area of white appears after about a minute the test is positive.[53]

Acetic acid is an effective antiseptic when used as a 1% solution, with broad spectrum of activity against streptococci, staphylococci, pseudomonas, enterococci and others.[54][55][56] It may be used to treat skin infections caused by pseudomonas strains resistant to typical antibiotics.[57]

While diluted acetic acid is used in iontophoresis, no high quality evidence supports this treatment for rotator cuff disease.[58][59]

As a treatment for otitis externa, it is on the World Health Organization`s List of Essential Medicines, the safest and most effective medicines needed in a health system.[60]

Foods

Main article: Vinegar

Acetic acid has 349 kcal per 100 g.[61] Vinegar is typically no less than 4% acetic acid by mass.[62][63][64] Legal limits on acetic acid content vary by jurisdiction. Vinegar is used directly as a condiment, and in the pickling of vegetables and other foods. Table vinegar tends to be more diluted (4% to 8% acetic acid), while commercial food pickling employs solutions that are more concentrated. The proportion of acetic acid used worldwide as vinegar is not as large as commercial uses, but is by far the oldest and best-known application.[65]

Reactions

Organic chemistry

acetyl chloride

Acetyl chloride.svg

SOCl2

Leftward reaction arrow

acetic acid

Acetic acid Structural Formula V1.svg

(i) LiAlH4, ether

Rightward reaction arrow

(ii) H

3O+

ethanol

Ethanol Skelett.svg

Two typical organic reactions of acetic acid

Acetic acid undergoes the typical chemical reactions of a carboxylic acid. Upon treatment with a standard base, it converts to metal acetate and water. With strong bases (e.g., organolithium reagents), it can be doubly deprotonated to give LiCH2CO2Li. Reduction of acetic acid gives ethanol. The OH group is the main site of reaction, as illustrated by the conversion of acetic acid to acetyl chloride. Other substitution derivatives include acetic anhydride; this anhydride is produced by loss of water from two molecules of acetic acid. Esters of acetic acid can likewise be formed via Fischer esterification, and amides can be formed. When heated above 440 C (824 F), acetic acid decomposes to produce carbon dioxide and methane, or to produce ketene and water:[66][67][68]

CH3COOH → CH4 + CO2

CH3COOH → CH2CO + H2O

Reactions with inorganic compounds

Acetic acid is mildly corrosive to metals including iron, magnesium, and zinc, forming hydrogen gas and salts called acetates:

Mg + 2 CH3COOH → (CH3COO)2Mg + H2

Because aluminium forms a passivating acid-resistant film of aluminium oxide, aluminium tanks are used to transport acetic acid. Metal acetates can also be prepared from acetic acid and an appropriate base, as in the popular “baking soda + vinegar” reaction:

NaHCO3 + CH3COOH → CH3COONa + CO2 + H2O

A colour reaction for salts of acetic acid is iron(III) chloride solution, which results in a deeply red colour that disappears after acidification.[69] A more sensitive test uses lanthanum nitrate with iodine and ammonia to give a blue solution.[70] Acetates when heated with arsenic trioxide form cacodyl oxide, which can be detected by its malodorous vapours.[71]

Other derivatives

Organic or inorganic salts are produced from acetic acid. Some commercially significant derivatives:

Sodium acetate, used in the textile industry and as a food preservative (E262).

Copper(II) acetate, used as a pigment and a fungicide.

Aluminium acetate and iron(II) acetate-used as mordants for dyes.

Palladium(II) acetate, used as a catalyst for organic coupling reactions such as the Heck reaction.

Halogenated acetic acids are produced from acetic acid. Some commercially significant derivatives:

Chloroacetic acid (monochloroacetic acid, MCA), dichloroacetic acid (considered a by-product), and trichloroacetic acid. MCA is used in the manufacture of indigo dye.

Bromoacetic acid, which is esterified to produce the reagent ethyl bromoacetate.

Trifluoroacetic acid, which is a common reagent in organic synthesis.

Amounts of acetic acid used in these other applications together account for another 5-10% of acetic acid use worldwide.[31]

History

Vinegar was known early in civilization as the natural result of exposure of beer and wine to air, because acetic acid-producing bacteria are present globally. The use of acetic acid in alchemy extends into the 3rd century BC, when the Greek philosopher Theophrastus described how vinegar acted on metals to produce pigments useful in art, including white lead (lead carbonate) and verdigris, a green mixture of copper salts including copper(II) acetate. Ancient Romans boiled soured wine to produce a highly sweet syrup called sapa. Sapa that was produced in lead pots was rich in lead acetate, a sweet substance also called sugar of lead or sugar of Saturn, which contributed to lead poisoning among the Roman aristocracy.[72]

In the 16th-century German alchemist Andreas Libavius described the production of acetone from the dry distillation of lead acetate, ketonic decarboxylation. The presence of water in vinegar has such a profound effect on acetic acid`s properties that for centuries chemists believed that glacial acetic acid and the acid found in vinegar were two different substances. French chemist Pierre Adet proved them identical.[72][73]

glass beaker of crystallised acetic acid

Crystallised acetic acid.

In 1845 German chemist Hermann Kolbe synthesised acetic acid from inorganic compounds for the first time. This reaction sequence consisted of chlorination of carbon disulfide to carbon tetrachloride, followed by pyrolysis to tetrachloroethylene and aqueous chlorination to trichloroacetic acid, and concluded with electrolytic reduction to acetic acid.[74]

By 1910, most glacial acetic acid was obtained from the pyroligneous liquor, a product of the distillation of wood. The acetic acid was isolated by treatment with milk of lime, and the resulting calcium acetate was then acidified with sulfuric acid to recover acetic acid. At that time, Germany was producing 10,000 tons of glacial acetic acid, around 30% of which was used for the manufacture of indigo dye.[72][75]

Because both methanol and carbon monoxide are commodity raw materials, methanol carbonylation long appeared to be attractive precursors to acetic acid. Henri Dreyfus at British Celanese developed a methanol carbonylation pilot plant as early as 1925.[76] However, a lack of practical materials that could contain the corrosive reaction mixture at the high pressures needed (200 atm or more) discouraged commercialization of these routes. The first commercial methanol carbonylation process, which used a cobalt catalyst, was developed by German chemical company BASF in 1963. In 1968, a rhodium-based catalyst (cis-[Rh(CO)2I2]-) was discovered that could operate efficiently at lower pressure with almost no by-products. US chemical company Monsanto Company built the first plant using this catalyst in 1970, and rhodium-catalyzed methanol carbonylation became the dominant method of acetic acid production (see Monsanto process). In the late 1990s, the chemicals company BP Chemicals commercialised the Cativa catalyst ([Ir(CO)2I2]-), which is promoted by iridium[77] for greater efficiency. This iridium-catalyzed Cativa process is greener and more efficient[35] and has largely supplanted the Monsanto process, often in the same production plants.

Interstellar medium

Interstellar acetic acid was discovered in 1996 by a team led by David Mehringer[78] using the former Berkeley-Illinois-Maryland Association array at the Hat Creek Radio Observatory and the former Millimeter Array located at the Owens Valley Radio Observatory. It was first detected in the Sagittarius B2 North molecular cloud (also known as the Sgr B2 Large Molecule Heimat source). Acetic acid has the distinction of being the first molecule discovered in the interstellar medium using solely radio interferometers; in all previous ISM molecular discoveries made in the millimetre and centimetre wavelength regimes, single dish radio telescopes were at least partly responsible for the detections.[78]

Health effects and safety

Concentrated acetic acid is corrosive to skin.[79][80] These burns or blisters may not appear until hours after exposure.

Prolonged inhalation exposure (eight hours) to acetic acid vapours at 10 ppm can produce some irritation of eyes, nose, and throat; at 100 ppm marked lung irritation and possible damage to lungs, eyes, and skin may result. Vapour concentrations of 1,000 ppm cause marked irritation of eyes, nose and upper respiratory tract and cannot be tolerated. These predictions were based on animal experiments and industrial exposure.

In 12 workers exposed for two or more years to acetic acid airborne average concentration of 51 ppm (estimated), produced symptoms of conjunctive irritation, upper respiratory tract irritation, and hyperkeratotic dermatitis. Exposure to 50 ppm or more is intolerable to most persons and results in intensive lacrimation and irritation of the eyes, nose, and throat, with pharyngeal oedema and chronic bronchitis. Unacclimatised humans experience extreme eye and nasal irritation at concentrations in excess of 25 ppm, and conjunctivitis from concentrations below 10 ppm has been reported. In a study of five workers exposed for seven to 12 years to concentrations of 80 to 200 ppm at peaks, the principal findings were blackening and hyperkeratosis of the skin of the hands, conjunctivitis (but no corneal damage), bronchitis and pharyngitis, and erosion of the exposed teeth (incisors and canines).[81]

The hazards of solutions of acetic acid depend on the concentration. The following table lists the EU classification of acetic acid solutions:[82]

Concentration

by weight Molarity Classification R-Phrases

10-25% 1.67-4.16 mol/L Irritant (Xi) R36/38

25-90% 4.16-14.99 mol/L Corrosive (C) R34

>90% >14.99 mol/L Corrosive (C) Flammable (F) R10, R35

Concentrated acetic acid can be ignited only with difficulty at standard temperature and pressure, but becomes a flammable risk in temperatures greater than 39 C (102 F), and can form explosive mixtures with air at higher temperatures (explosive limits: 5.4-16%).

Acetic acid, systematically named ethanoic acid, is a colourless liquid organic compound with the chemical formula CH3COOH (also written as CH3CO2H or C2H4O2). When undiluted, it is sometimes called glacial acetic acid. Vinegar is no less than 4% acetic acid by volume, making acetic acid the main component of vinegar apart from water. Acetic acid has a distinctive sour taste and pungent smell. In addition to household vinegar, it is mainly produced as a precursor to polyvinyl acetate and cellulose acetate. It is classified as a weak acid since it only partially dissociates in solution, but concentrated acetic acid is corrosive and can attack the skin.

The global demand for acetic acid is about 6.5 million metric tons per year (Mt/a), of which approximately 1.5 Mt/a is met by recycling; the remainder is manufactured from methanol. Vinegar is mostly dilute acetic acid, often produced by fermentation and subsequent oxidation of ethanol.

Acetic acid, also known as ethanoic acid, is an organic chemical compound best recognized for giving vinegar its sour taste and pungent smell. It is one of the simplest carboxylic acids (the second-simplest, after formic acid) and has the chemical formula CH3COOH. In its pure, water-free state, called glacial acetic acid, it is a colorless, hygroscopic liquid that freezes below 16.7C (62F) to a colorless crystalline solid. It is corrosive, and its vapor irritates the eyes, produces a burning sensation in the nose, and can lead to a sore throat and lung congestion. The term acetate is used when referring to the carboxylate anion (CH3COO-) or any of the salts or esters of acetic acid.

This acid is an important chemical reagent and industrial chemical useful for the production of various synthetic fibers and other polymeric materials. These polymers include polyethylene terephthalate, used mainly in soft drink bottles; cellulose acetate, used mainly for photographic film; and polyvinyl acetate, for wood glue. In households, diluted acetic acid is often used in descaling agents. The food industry uses it (under the food additive code E260) as an acidity regulator.

NOMENCLATURE

The trivial name acetic acid is the most commonly used and officially preferred name by the International Union of Pure and Applied Chemistry (IUPAC). This name derives from acetum, the Latin word for vinegar. The synonym ethanoic acid is a systematic name that is sometimes used in introductions to chemical nomenclature.

Glacial acetic acid is a trivial name for water-free acetic acid. Similar to the German name Eisessig (literally, ice-vinegar), the name comes from the ice-like crystals that form slightly below room temperature at 16.7C (about 62F).

The most common and official abbreviation for acetic acid is AcOH or HOAc where Acstands for the acetyl group CH3-C(=O)-;. In the context of acid-base reactions the abbreviation HAc is often used where Acinstead stands for the acetate anion(CH3COO-), although this use is regarded by many as misleading. In either case, the Ac is not to be confused with the abbreviation for the chemical element actinium.

Acetic acid has the empirical formula CH2O and the molecular formula C2H4O2. The latter is often written as CH3-COOH, CH3COOH, or CH3CO2H to better reflect its structure. The ion resulting from loss of H+ from acetic acid is the acetate anion. The name acetate can also refer to a salt containing this anion or an ester of acetic acid.

HISTORY

Vinegar is as old as civilization itself, perhaps older. Acetic acid-producing bacteria are present throughout the world, and any culture practicing the brewing of beer or wine inevitably discovered vinegar as the natural result of these alcoholic beverages being exposed to air.

The use of acetic acid in chemistry extends into antiquity. In the third century B.C.E., Greek philosopher Theophrastos described how vinegar acted on metals to produce pigments useful in art, including white lead(lead carbonate) and verdigris, a green mixture of copper salts including copper(II) acetate. Ancient Romans boiled soured wine in lead pots to produce a highly sweet syrup called sapa. Sapa was rich in lead acetate, a sweet substance also called sugar of lead or sugar of Saturn, which contributed to lead poisoning among the Roman aristocracy. The eighth-century Persian alchemist Jabir Ibn Hayyan (Geber) concentrated acetic acid from vinegar through distillation.

In the Renaissance, glacial acetic acid was prepared through the dry distillation of metal acetates. The sixteenth-century German alchemist Andreas Libavius described such a procedure, and he compared the glacial acetic acid produced by this means to vinegar. The presence of water in vinegar has such a profound effect on acetic acid`s properties that for centuries many chemists believed that glacial acetic acid and the acid found in vinegar were two different substances. The French chemist Pierre Adet proved them to be identical.

In 1847, the German chemist Hermann Kolbe synthesized acetic acid from inorganic materials for the first time. This reaction sequence consisted of chlorination of carbon disulfide to carbon tetrachloride, followed by pyrolysis to tetrachloroethylene and aqueous chlorination to trichloroacetic acid, and concluded with electrolytic reduction to acetic acid.

By 1910, most glacial acetic acid was obtained from the “pyroligneous liquor” from distillation of wood. The acetic acid was isolated from this by treatment with milk of lime, and the resultant calcium acetate was then acidified with sulfuric acid to recover acetic acid. At this time Germany was producing 10,000 tons of glacial acetic acid, around 30 percent of which was used for the manufacture of indigo dye.[2][3]

BIOCHEMISTRY

The acetyl group, derived from acetic acid, is fundamental to the biochemistry of virtually all forms of life. When bound to coenzyme A it is central to the metabolism of carbohydrates and fats. However, the concentration of free acetic acid in cells is kept at a low level to avoid disrupting the control of the pH of the cell contents. Unlike some longer-chain carboxylic acids (the fatty acids), acetic acid does not occur in natural triglycerides. However, the artificial triglyceride triacetin (glycerin triacetate) is a common food additive, and is found in cosmetics and topical medicines.

Acetic acid is produced and excreted by certain bacteria, notably the Acetobacter genus and Clostridium acetobutylicum. These bacteria are found universally in foodstuffs, water, and soil, and acetic acid is produced naturally as fruits and some other foods spoil. Acetic acid is also a component of the vaginal lubrication of humans and other primates, where it appears to serve as a mild antibacterial agent.[7]

PRODUCTION

Acetic acid is produced both synthetically and by bacterial fermentation. Today, the biological route accounts for only about 10 percent of world production, but it remains important for vinegar production, as many of the world food purity laws stipulate that vinegar used in foods must be of biological origin. About 75 percent of acetic acid made for use in the chemical industry is made by methanol carbonylation, explained below. Alternative methods account for the rest.[8]

Total worldwide production of virgin acetic acid is estimated at 5 Mt/a (million metric tons per year), approximately half of which is produced in the United States. European production stands at approximately 1 Mt/a and is declining, and 0.7 Mt/a is produced in Japan. Another 1.5 Mt are recycled each year, bringing the total world market to 6.5 Mt/a.[9] The two biggest producers of virgin acetic acid are Celanese and BP Chemicals. Other major producers include Millennium Chemicals, Sterling Chemicals, Samsung, Eastman, and Svensk Etanolkemi.

Methanol carbonylation

Most virgin acetic acid is produced by methanol carbonylation. In this process, methanol and carbon monoxide react to produce acetic acid according to the chemical equation:

CH3OH + CO → CH3COOH

The process involves iodomethane as an intermediate, and occurs in three steps. A catalyst, usually a metal complex, is needed for the carbonylation (step 2).

(1) CH3OH + HI → CH3I + H2O

(2) CH3I + CO → CH3COI

(3) CH3COI + H2O → CH3COOH + HI

By altering the process conditions, acetic anhydride may also be produced on the same plant. Because both methanol and carbon monoxide are commodity raw materials, methanol carbonylation long appeared to be an attractive method for acetic acid production. Henry Drefyus at British Celanese developed a methanol carbonylation pilot plant as early as 1925.[10] However, a lack of practical materials that could contain the corrosive reaction mixture at the high pressures needed (200 atm or more) discouraged commercialisation of these routes for some time. The first commercial methanol carbonylation process, which used a cobalt catalyst, was developed by German chemical company BASF in 1963. In 1968, a rhodium-based catalyst (cis-[Rh(CO)2I2]-) was discovered that could operate efficiently at lower pressure with almost no by-products. The first plant using this catalyst was built by U.S. chemical company Monsanto in 1970, and rhodium-catalysed methanol carbonylation became the dominant method of acetic acid production (see Monsanto process). In the late 1990s, the chemicals company BP Chemicals commercialised the Cativa catalyst ([Ir(CO)2I2]-), which is promoted by ruthenium. This iridium-catalysed process is greener and more efficient[11] and has largely supplanted the Monsanto process, often in the same production plants.

Acetaldehyde oxidation

Prior to the commercialisation of the Monsanto process, most acetic acid was produced by oxidation of acetaldehyde. This remains the second most important manufacturing method, although it is uncompetitive with methanol carbonylation. The acetaldehyde may be produced via oxidation of butane or light naphtha, or by hydration of ethylene.

When butane or light naphtha is heated with air in the presence of various metal ions, including those of manganese, cobalt and chromium, peroxides form and then decompose to produce acetic acid according to the chemical equation

2 C4H10 + 5 O2 → 4 CH3COOH + 2 H2O

Typically, the reaction is run at a combination of temperature and pressure designed to be as hot as possible while still keeping the butane a liquid. Typical reaction conditions are 150 C and 55 atm. Several side products may also form, including butanone, ethyl acetate, formic acid, and propionic acid. These side products are also commercially valuable, and the reaction conditions may be altered to produce more of them if this is economically useful. However, the separation of acetic acid from these by-products adds to the cost of the process.

Under similar conditions and using similar catalysts as are used for butane oxidation, acetaldehyde can be oxidised by the oxygen in airto produce acetic acid

2 CH3CHO + O2 → 2 CH3COOH

Using modern catalysts, this reaction can have an acetic acid yield greater than 95%. The major side products are ethyl acetate, formic acid, and formaldehyde, all of which have lower boiling points than acetic acid and are readily separated by distillation.

ETHYLNE OXIDATION

FERMENTATION

Oxidative fermentation

For most of human history, acetic acid, in the form of vinegar, has been made by bacteria of the genus Acetobacter. Given sufficient oxygen, these bacteria can produce vinegar from a variety of alcoholic foodstuffs. Commonly used feeds include apple cider, wine, and fermented grain, malt, rice, or potato mashes. The overall chemical reaction facilitated by these bacteria is

C2H5OH + O2 → CH3COOH + H2O

One of the first modern commercial processes was the “fast method” or “German method,” first practised in Germany in 1823. In this process, fermentation takes place in a tower packed with wood shavings or charcoal. The alcohol-containing feed is trickled into the top of the tower, and fresh air supplied from the bottom by either natural or forced convection. The improved air supply in this process cut the time to prepare vinegar from months to weeks.

Most vinegar today is made in submerged tank culture, first described in 1949 by Otto Hromatka and Heinrich Ebner. In this method, alcohol is fermented to vinegar in a continuously stirred tank, and oxygen is supplied by bubbling air through the solution. Using this method, vinegar of 15 percent acetic acid can be prepared in only two to three days.

Anaerobic fermentation

Some species of anaerobic bacteria, including several members of the genus Clostridium, can convert sugars to acetic acid directly, without using ethanol as an intermediate. The overall chemical reaction conducted by these bacteria may be represented as:

C6H12O6 → 3 CH3COOH

More interestingly from the point of view of an industrial chemist, many of these acetogenic bacteria can produce acetic acid from one-carbon compounds, including methanol, carbon monoxide, or a mixture of carbon dioxide and hydrogen:

2 CO2 + 4 H2 → CH3COOH + 2 H2O

This ability of Clostridium to utilise sugars directly, or to produce acetic acid from less costly inputs, means that these bacteria could potentially produce acetic acid more efficiently than ethanol-oxidisers like Acetobacter. However, Clostridium bacteria are less acid-tolerant than Acetobacter. Even the most acid-tolerant Clostridium strains can produce vinegar of only a few per cent acetic acid, compared to some Acetobacter strains that can produce vinegar of up to 20 percent acetic acid. At present, it remains more cost-effective to produce vinegar using Acetobacter than to produce it using Clostridium and then concentrating it. As a result, although acetogenic bacteria have been known since 1940, their industrial use remains confined to a few niche applications.

APPLICATIONS

Acetic acid is a chemical reagent for the production of many chemical compounds. The largest single use of acetic acid is in the production of vinyl acetate monomer, closely followed by acetic anhydride and ester production. The volume of acetic acid used in vinegar is comparatively small.

OTHER APPLICATIONS

Dilute solutions of acetic acids are also used for their mild acidity. Examples in the household environment include the use in a stop bath during the development of photographic films, and in descaling agents to remove limescale from taps and kettles. The acidity is also used for treating the sting of the box jellyfish by disabling the stinging cells of the jellyfish, preventing serious injury or death if applied immediately, and for treating outer ear infections in people in preparations such as Vosol. Equivalently, acetic acid is used as a spray-on preservative for livestock silage, to discourage bacterial and fungal growth.

Glacial acetic acid is also used as a wart and verruca remover. A ring of petroleum jelly is applied to the skin around the wart to prevent spread, and one to two drops of glacial acetic acid are applied to the wart or verruca. Treatment is repeated daily. This method is painless and has a high success rate, unlike many other treatments. Absorption of glacial acetic acid is safe in small amounts.

Several organic or inorganic salts are produced from acetic acid, including:

Sodium acetate-used in the textile industry and as a food preservative (E262).

Copper(II) acetate-used as a pigment and a fungicide.

Aluminium acetate and iron(II) acetate-used as mordants for dyes.

Palladium(II) acetate-used as a catalyst for organic coupling reactions such as the Heck reaction.

Substituted acetic acids produced include:

Monochloroacetic acid (MCA), dichloroacetic acid (considered a by-product), and trichloroacetic acid. MCA is used in the manufacture of indigo dye.

Bromoacetic acid, which is esterified to produce the reagent ethyl bromoacetate.

Trifluoroacetic acid, which is a common reagent in organic synthesis.

Amounts of acetic acid used in these other applications together (apart from TPA) account for another 5-10 percent of acetic acid use worldwide. These applications are, however, not expected to grow as much as TPA production.

SAFETY

Concentrated acetic acid is corrosive and must therefore be handled with appropriate care, since it can cause skin burns, permanent eye damage, and irritation to the mucous membranes. These burns or blisters may not appear until several hours after exposure. Latex gloves offer no protection, so specially resistant gloves, such as those made of nitrile rubber, should be worn when handling the compound. Concentrated acetic acid can be ignited with some difficulty in the laboratory. It becomes a flammable risk if the ambient temperature exceeds 39 C (102 F), and can form explosive mixtures with air above this temperature (explosive limits: 5.4-16 percent).

The hazards of solutions of acetic acid depend on the concentration.

Asetik asit

Asetik asit-2D-skeletal.svg

Asetik asit-CRC-GED-3D-balls-B.png

Asetik asit-2D-flat.png

Asetik asit-CRC-GED-3D-vdW-B.png

Asetik asit.jpg

IUPAC ad[gizle]

Asetik asit[1][2]

Sistematik ad[gizle]

Etanoik asit

Dier adlar[gizle]

Sirke (seyrek olduunda); Hidrojen asetat; Metankarboksilik asit[3][4]

Tanmlayclar

Ksaltmalar AcOH

Asetik asit CAS numaras 64-19-7

PubChem 176

Asetik asit EC numaras 200-580-7

Asetik asit UN numaras 2789

DrugBank DB03166

KEGG D00010

MeSH Acetic+acid

Asetik asit ChEBI 15366

RTECS numaras AF1225000

SMILES

[gster]

Beilstein 506007

Gmelin veritaban 1380

ChemSpider 171

3DMet B00009

Asetik asit zellikler

Asetik asit Kimyasal forml C2H4O2

Asetik asit Molekl ktlesi 60,05 g mol-1

Asetik asit Grnm Renksiz sv

Asetik asit Koku Keskin, sirke gibi

Asetik asit Younluk 1.049 g cm-3

Asetik asit Erime noktas

16-17 C; 61-62 F; 289-290 K

Asetik asit Kaynama noktas

118-119 C; 244-246 F; 391-392 K

Asetik asit znrlk (su iinde) Karabilir.

log P -0.322

Asitlik (pKa) 4.76[5]

Baziklik (pKb) 9.24 (Asetat iyonunun baziklii)

Tehlikeler

NFPA 704

NFPA 704.svg230

Parlama noktas 40 C (104 F; 313 K)

ztutuma

scakl 427 C (801 F; 700 K)

Patlama snrlar 4-16%

ABD maruz

kalma limiti (PEL) TWA 10 ppm (25 mg/m)

LD50 3.31 g kg-1, oral (san)

Belirtilmi yerler dnda verilmi olan veriler, Standart scaklk ve basntadr. (25 C, 100 kPa)

Bilgi kutusu kaynaklar

Asetik asit veya etanoik asit CH3COOH formll bir organik asittir, sirkeye eki tadn ve keskin kokusunu vermesiyle bilinir. Karboksilik asitlerin en kklerindendir (en kk olan formik asittir). Doada karbonhidratlarn ykseltgenmesiyle oluur. Sanayide asetik asit hem biyolojik yolla hem de sentetik yolla imal edilir. Tuz ve esterine asetat denir. Suda tamamen znr.

Kullanm

Sirke

Sirke genelde %4-5 orannda asetik asit ierir ama turu kurmak iin kullanlan sirkelerde bu oran %18`e varr. Sirkenin oluturduu asitli ortam gdalarn bozulmasna neden olacak ou mikroorganizmann bymesini engeller. Bu yzden turulama sebzelerin mrn uzatmak iin etkili bir yntemdir.

Sanayi

Donmu asetik asit

Sanayide asetik asitin geni bir kullanm alan vardr, ou kimyasaln retiminde hammadde olarak kullanlr. En nemli kullanm vinil asetat retimidir ve bundan elde edilen polivinil asetat tahta tutkal olarak kullanlr. Bunu asetik anhidrit ve asetik ester retimi izler. Sirke retiminde kullanm nispeten nemsizdir. Asetik asitin bir dier nemli kullanm zc olaraktr. PET plastiklerin retiminde kullanlan tereftalik asit retiminde asetik asit zc olarak kullanlr, bu kullanm asetik asitin tm kullanmnn %5-10`unu oluturur. Asetik asit gda sanayisinden tampon zelliinden dolay E260 adyla bir katk maddesi olarak kullanlr.

Asetik asidin trevlerinin de eitli kullanmlar vardr. rnein, Sodyum asetat dokuma sanayinde ve gda katk maddesi olarak (E262) kullanlr. Selloz asetat fotoraf filmi retiminde kullanlr.

Asetik asidin zayf bir asit olmas onun zellikle ev iinde temizleme amacyla kullanlmasnn nedenidir. Seyreltik asetik asit (sirke) aydanlklarn kireten arndrlmasnda, cam ve dier parlak yzeylerdeki maden birikmeleri temizlemekte kullanlabilir.

Etkileri

Emniyet ikaz

Youn asetik asit cildi yakar, gze kalc zarar verir ve ciltte kabarcklar olumasna neden olur. Etkileri birka saat sonra hissedilir. Bu etkilerden korunmak iin nitril koruma eldivenleri giyilir . Asetik asit 39 C zerinde tutuabilir, havayla patlayc karmlar oluturabilir.

%25`den daha youn asetik asit labarutuarlarda ekerocak altnda kullanlmaldr. Seyreltik asetik asit zararszdr, ama daha kuvvetli zeltileri insan ve hayvanlar iin zararldr. Sindirim sistemine ciddi hasar verebilir ve kan asitliini lmcl oranda deitirebilir.

ASETK AST

Grnm : Renksiz Sv Haldedir.

Kimyasal Ad : E260, Sirke Asidi, Etanoik Asit

Kimyasal Forml : CH3COOH

Ambalaj ekli : 60 kg. lk Bidonlarda, 1 Tonluk Konteynerlarda

Tanm ve Kullanm Alanlar :

Sanayide biyolojik ve sentetik yollar ile imal edilir. Tuz ve esterine asetat denir. Suda tamamen znr. Zayf bir asittir. Asetik asidin glasiel asetik asit tr % 99,5 saf asetik asit iermektedir. Asetik asidin bu % 99,5`lik glasiel formu 17C`de katlar ve kristalimsi buz taneciklerine benzer bir yap oluturur.

Kullanm Alanlar

Sirke imalatnda kullanlr. Ayrca turu yapmnda mikroorganizmalarn olumasn engelleyerek sebzelerin bozulmasn engeller.

Sanayide ou kimyasaln retiminde hammadde olarak kullanlr. zellikle vinil asetat retiminde kullanlr, bundan elde edilen polivinil asetat tahta tutkal olarak kullanlr.

zc olarak sanayide kullanlr. rnein, PET plastiklerin retiminde kullanlan tereftalik asitin retiminde zc olarak kullanlr. Bu kullanm asetik asitin tm kullanm ierisinde %5-10 oranndadr.

4. Gda sektrnde tampon olarak kullanlr. Asitlik salayc, koruyucu, lezzet verici olarak kullanlr.

Asetik asit, etanoik asit ya da sirke asidi olarak ta anlan, CH3COOH ak formll, C2H4O2 kapal formll organik bir asittir. Sirkenin keskin kokusunu ve eki tadn veren asittir. Karboksilik asitler arasnda en nemlisi ve en kdr. Karbonhidratlarn doada ykseltgenmesiyle elde edilir. Sanayi sektrnde biyolojik ve sentetik olarak elde edilebilir. Suda tamamen znen asetik asidin tuz ve esterine asetat ad verilir. Kimya sektrnde etanoik asit olarak anlr. Saf asetik asit keskin, renksiz, ineleyici bir kokuda olup, 118 derecede kaynar, 16,7 derecede donar. Suya kartnda suyu eker, cildi tahri eder ve metalleri andrr. arap ya da mayann mayalanmasyla elde edilen sirkenin temel maddesi asetik asittir.

Asetik asidin elde edilmesi

Baz meyve sularnda bulunan eker mayalarn etkisiyle birlikte etil alkole dnmektedir. Bu alkol de micoderma denen bakteriyle asetik aside dnmektedir. Bu yntemin dnda asetik asit, etil alkoln oksidasyonuyla, metil alkol reaksiyonuyla elde edilebilir. Eczaclk alannda asetik asit en nemli kimyasaldr. rnein aspirin retiminde kullanlr. Mikrop ve haere ldren bakr asetat ile bakr aseto arsenitin balang maddesi asetik asittir. Selloz triasetat retiminde kullanlr. Bundan asetat iplikleri oluturulur. Bunlardan da fotoraf filmi, geiren katlar elde edilir. Yine asetik asitten retilen etil asetat vernik retiminde kullanlmaktadr. Matbaa sektrnde kullanlan metal asetatlarn da balang maddesidir.

Asetik asidin kullanm alanlar

Sirke yapmnda: Sirkenin ierii ortalama % 4-5 orannda asetik asit iermektedir. Turu yapmnda kullanlan sirkelerde ise, % 18 orannda asetik asit bulunabilir. Sirke oluturduu asitli ortam nedeniyle, besinlerin bozulmasna neden olan mikroorganizmalarn bymesini engellenmektedir. Turu yapmnda gdalarn mrn uzatmak iin, sirke kullanm olduka etkilidir.

Sanayi sektrnde: Sanayide olduka geni bir kullanm olan asetik asit, kimyasallarn retiminde hammadde olarak deerlendirilir. Vinil asetat retiminde youn ekilde kullanlr. Bundan tahta tutkal elde edilir. Asetik ester ve asetik anhidrit retiminde de yararlanlr. Ayrca zc olarak kullanlr. Pet plastik retiminde kullanlan tereftalik asidin retiminde zc olarak kullanlmaktadr. Bu asetik asidin kullanmnn yaklak % 5-10 kadarn oluturur. Gda sektrnde tampon zellii olduundan, E260 olarak katk maddesi olarak kullanlmaktadr. Bunun trevleri de farkl alanlarda kullanlmaktadr. E262 adyla dokuma sektrnde ve gda katks olarak sodyum asetat kullanlr. Fotoraf filmi retiminde selloz asetat kullanlr. Zayf bir asit olduundan, ev temizliinde yararlanlr. zellikle aydanlklarn kirelerinin temizlenmesinde, parlak yzeylerde ve camlardaki madeni birikimlerin temizlenmesinde kullanlr.

Asetik asit kullanlrken dikkat edilmesi gerekenler

Youn ekilde kullanm cildi tahri eder, gzlerde kalc hasarlar oluturabilir, ciltte kabarcklar meydana getirir. Kullanmdan sonra birka saatte bu etkiler grlebilir. Korunmak iin nitril eldivenler kullanlmaldr. 39 derecenin zerinde tutuma zellii vardr. Bu nedenle havayla patlayc karmlar meydana getirebilir. Younluu % 25 ten fazla olduunda, keskinlii ve yakclyla laboratuvarda kullanlmas ok zor olur. Seyreltilmi asetik asit genellikle zararszdr. Ancak kuvvetli zeltiler sindirim sistemine hasar verebilir, kandaki asitlii lmcl seviyede deitirebilir.

Asetik asit ya da Avrupa Birliinin verdii adyla E260 bitki ve hayvan dokularnda doal olarak bulunan bir organik asittir. Sirkenin balca bileeni olan asetik asit ticari olarak bakteriyel fermentasyon ya da metanoldan kimyasal sentez yoluyla elde edilmektedir. Kimyada bilinirlii ok eski zamanlara dayanan asetik asit ilk defa 8. yzylda mslman bilim adam Cabir bin Hayyan tarafndan sirkeden distilasyon yoluyla konsantre edilerek retilmitir. Gda sanayinde katk maddesi olarak ve sirke retiminde kullanlan asetik asit kimya sanayinin ok nemli bir hammaddesidir. Yapkan, boya ve eitli plastiklerin retiminde kullanlan bileiklerin elde edilmesinde asetik asit reaktif madde ya da zc olarak ilev grmektedir. Gdalarda kullanm ile ilgili bir snrlama olmayan asetik asit ABD Gda ve la Dairesi tarafndan katk maddeleri iin oluturulan GRAS (Genellikle Gvenli Kabul Edilir) listesinde yer almaktadr.

ASETK AST(ACETIC ACID)

Sistemik olarak adlandrlan etanoik asit olan asetik asit, CH3COOH (CH3CO2H veya C2H4O2 olarak da yazlr) kimyasal formlne sahip renksiz bir sv organik bileiktir. Seyreltilmemi zaman, bazen buzlu asetik asit denir. Sirke, hacimce% 4`ten az asetik asittir, asetik asit, sudan baka sirkenin ana bileenini oluturur. Asetik asit, kendine zg bir eki tad ve keskin kokusu vardr. Ev sirkesine ek olarak, esas olarak polivinil asetat ve selloz asetatn bir ncs olarak retilir. zeltide sadece ksmen ayrt iin zayf bir asit olarak snflandrlr, ancak konsantre asetik asit andrcdr ve cilde saldrabilir. Asetik asit ikinci en basit karboksilik asittir (formik asit sonras). Bir karboksil grubuna bal bir metil grubundan oluur. ncelikle fotografik film iin selloz asetat, ahap tutkal iin polivinil asetat ve sentetik elyaf ve kuma retiminde kullanlan nemli bir kimyasal reaktif ve endstriyel kimyasaldr. Hanelerde, seyreltilmi asetik asit, kire zc ajanlarda sklkla kullanlr. Gda endstrisinde, asetik asit gda katk maddesi kodu E260 tarafndan bir asit dzenleyici ve bir baharat olarak kontrol edilir. Biyokimyada, asetik asitten tretilen asetil grubu, tm yaam formlar iin temeldir. Koenzim A`ya balandnda, karbonhidrat ve ya metabolizmasnn merkezinde yer alr. Asetik asit iin kresel talep ylda yaklak 6,5 milyon mt (Mt / a) olup, bunun yaklak 1.5 Mt / a geri dnm ile karlanmasdr; geri kalan ksm metanolden retilmitir. Sirke ounlukla fermantasyon ve daha sonra etanoln oksidasyonu ile retilen, ounlukla seyreltik asetik asittir.

Asetik asit en basit karboksilik asitlerden biridir. Plastik merubat ieleri, fotoraf filmi retiminde kullanlan nemli bir kimyasal reaktif ve endstriyel kimyasaldr; ve ahap tutkal iin birok sentetik elyaf ve kuma iin polivinil asetat. Evlerde seyreltilmi asetik asit genellikle temizlik maddesi olarak kullanlr. Gda endstrisinde asetik asit bir asit dzenleyici olarak kullanlr. Asetik asitten tretilen asetil grubu, neredeyse tm yaam formlarnn biyokimyas iin temeldir. Koenzim A`ya balandnda, karbonhidrat ve ya metabolizmasnn merkezi olur. Bununla birlikte, hcrelerde serbest asetik asitin konsantrasyonu, hcre ieriinin pH`nn kontroln bozmaktan kanmak iin dk bir seviyede tutulur. Asetik asit, baz bakteriler, zellikle de Acetobacter cinsi ve Clostridium acetobutylicum tarafndan retilir ve dar atlr. Bu bakteriler genel olarak gda maddelerinde, suda ve toprakta bulunurlar ve asetik asit, meyveler ve dier baz gdalar bozulduunda doal olarak retilir. Asetik asit ayn zamanda insanlarda ve dier primatlarn vajinal yalanmasnn bir bileenidir ve hafif bir antibakteriyel madde olarak hizmet ettii grlmektedir. Asetik asitin metabolizmann doutan gelen bir hatas olan fenilketonri ile ilikili olduu bulunmutur.

Etanoik asit olarak da bilinen asetik asit, sirke eki tat ve keskin kokusunu vermek iin en iyi tannan organik bir kimyasal bileiktir. En basit karboksilik asitlerden biridir (ikinci en basit, formik asit sonras) ve CH3COOH kimyasal formlne sahiptir. Saf, asetik asit olarak adlandrlan saf, su iermeyen durumunda, renksiz, higroskopik bir svdr ve 16,7 C`nin (62 F) altnda renksiz bir kristalin katya kadar donar. Andrcdr ve buhar gzleri tahri eder, burunda yanma hissi yaratr ve boaz arsna ve akcier tkanklna yol aabilir. Asetat terimi, karboksilat anyonuna (CH3COO-) veya asetik asidin tuzlarndan veya esterlerinden herhangi birine bavururken kullanlr.

Bu asit, eitli sentetik liflerin ve dier polimerik malzemelerin retimi iin yararl olan nemli bir kimyasal reaktif ve endstriyel kimyasaldr. Bu polimerler arasnda esas olarak merubat ielerinde kullanlan polietilen tereftalat; ounlukla fotografik film iin kullanlan selloz asetat; ve ahap tutkal iin polivinil asetat. Hanelerde, seyreltilmi asetik asit, kire zc ajanlarda sklkla kullanlr. Gda endstrisi, bir asitlik dzenleyici olarak (E260 gda katk maddesi kodunun altnda) kullanr.

TERMNOLOJ

Asil asidin nemsiz ad, Uluslararas Saf ve Uygulamal Kimya Birlii (IUPAC) tarafndan en ok kullanlan ve resmen tercih edilen isimdir. Bu isim asetil, sirke iin Latince kelimesinden tremitir. Eanlaml etanoik asit, bazen kimyasal isimlendirmeye girilerde kullanlan sistematik bir isimdir.

Buzlu asetik asit, su iermeyen asetik asit iin nemsiz bir isimdir. Eisessig (tam anlamyla buz sirkesi) Alman ismine benzer ekilde, isim 16.7 C`de (yaklak 62 F) oda scaklnn biraz altnda olan buz benzeri kristallerden gelmektedir.

Asetik asit iin en yaygn ve resmi ksaltma, AcOH grubu CH3 – C (= O) -; olduu AcOH veya HOAc`dir. Asit-baz reaksiyonlar balamnda, genellikle Acinstead`in asetat anyonunu (CH3COO-) temsil ettii, ancak bu kullanmn yanltc olduu dnlrse, HAc ksaltmas kullanlr. Her iki durumda da, Ac kimyasal element aktinyumunun ksaltmas ile kartrlmamaldr.

Asetik asit, CH2O ampirik formlne ve C2H4O2 molekler formlne sahiptir. kincisi genellikle yapsn daha iyi yanstmak iin CH3-COOH, CH3COOH veya CH3CO2H olarak yazlr. Asetik asitin H + kaybndan kaynaklanan iyon, asetat anyonudur. Asetat, ayn zamanda, bu anyonu ieren bir tuzu veya asetik asidin bir esteri anlamna da gelebilir.

TARHE

Sirke, medeniyetin kendisi kadar eskidir, belki daha yaldr. Asetik asit reten bakteriler tm dnyada mevcuttur ve bira veya arabn demlenmesini salayan herhangi bir kltr kanlmaz olarak bu alkoll ieceklerin havaya maruz kalmasnn doal sonucu olarak sirke kefettiler.

Kimyada asetik asit kullanm antiklie kadar uzanr. nc yzylda, Yunan filozof Theophrastos, sirkenin, bakr (II) asetat ieren bakr bir bakr tuzlar karm olan beyaz kurun (kurun karbonat) ve verdigris de dahil olmak zere, sanatta yararl pigmentler retmek iin metaller zerinde nasl hareket ettiini tarif etmitir. Eski Romallar, sapa ad verilen ok tatl bir urup retmek iin kurun tencerede asitli arap kaynatmlard. Sapa, Roma aristokrasisi arasnda kurun zehirlenmesine katkda bulunan, kurun eker veya Satrn eker gibi tatl bir madde olan kurun asetat asndan zengindi. Sekizinci yzyl Farsa simyac Jabir Ibn Hayyan (Geber), asetik asidi sirkeden distilasyon yoluyla konsantre etti.

Rnesansta, buzlu asetik asit, metal asetatlarn kuru damtlmasyla hazrland. On altnc yzylda Alman simyac Andreas Libavius byle bir prosedr tanmlad ve bu yntemle retilen buzlu asetik asidi sirke ile karlatrd. Sirkede suyun varl asetik asitin zellikleri zerinde ok byk bir etkiye sahiptir. Yzyllar boyunca birok kimyager buzul asetik asit ve sirke iinde bulunan asidin iki farkl madde olduuna inanrlard. Fransz kimyac Pierre Adet, onlarn ayn olduunu kantlad.

1847`de, Alman kimyac Hermann Kolbe ilk kez inorganik materyallerden asetik asit sentezlemitir. Bu reaksiyon dizisi karbon dislfidden karbon tetraklorre klorinasyonu, ardndan tetrakloretilene ve sulu klorinasyona trikloroasetik aside kadar pirolizden olumaktayd ve asetik aside elektrolitik indirgeme ile sonlandrld.

1910`a gelindiinde, ou buzlu asetik asit, odunun damtlmasndan “pirolitik likr” den elde edildi. Asetik asit bundan sonra kire st ile muamele edilerek izole edilmi ve sonuta meydana gelen kalsiyum asetat asetik asidi geri kazanmak iin slfrik asit ile asitletirilmitir. Bu srada Almanya, yaklak% 30`u indigo boya retimi iin kullanlan 10.000 tonluk glasiyal asetik asit retiyordu. [2] [3]

BIOKIMYA

Asetik asitten tretilen asetil grubu, neredeyse tm yaam formlarnn biyokimyas iin temeldir. Koenzim A`ya balandnda, karbonhidrat ve ya metabolizmasnn merkezi olur. Bununla birlikte, hcrelerde serbest asetik asitin konsantrasyonu, hcre ieriinin pH`nn kontroln bozmaktan kanmak iin dk bir seviyede tutulur. Baz uzun zincirli karboksilik asitlerin (ya asitleri) aksine, doal trigliseritlerde asetik asit olumaz. Bununla birlikte, yapay trigliserit triasetin (gliserin triasetat) yaygn bir gda katksdr ve kozmetikte ve topikal ilalarda bulunur.

Asetik asit, baz bakteriler, zellikle de Acetobacter cinsi ve Clostridium acetobutylicum tarafndan retilir ve dar atlr. Bu bakteriler genel olarak gda maddelerinde, suda ve toprakta bulunurlar ve asetik asit, meyveler ve dier baz gdalar bozulduunda doal olarak retilir. Asetik asit ayn zamanda insanlarda ve dier primatlarn vajinal yalanmasnn bir bileeni olup, hafif bir antibakteriyel ajan olarak hizmet ettii grlmektedir. [7]

RETM

Asetik asit hem sentetik hem de bakteriyel fermantasyon ile retilir. Bugn, biyolojik rota dnya retiminin sadece yzde 10`unu oluturuyor, ancak dnyadaki gda saflk yasalarnn ou gdalarda kullanlan sirkenin biyolojik kkenli olmasn art kotuu iin, sirke retimi iin nemini koruyor. Kimyasal endstrisinde kullanlmak zere retilen asetik asitin yaklak yzde 75`i, aada aklanm olan metanol karbonilasyon ile yaplmtr. Alternatif yntemler dierlerini aklar. [8]

Dnya apnda toplam bakire asetik asit retimi yaklak olarak Amerika Birleik Devletleri`nde yaklak olarak yars retilen 5 Mt / a (ylda milyon metrik ton) olarak tahmin edilmektedir. Avrupa retimi yaklak 1 Mt / a seviyesinde ve d gsteriyor ve Japonya`da 0.7 Mt / a retiliyor. Her yl 1,5 Mt daha geri dntrlmekte ve dnya piyasasn 6,5 Mt / a seviyesine karmaktadr. [9] En byk iki asetik asit reticisi Celanese ve BP Chemicals`dr. Dier nemli reticiler arasnda Millennium Chemicals, Sterling Chemicals, Samsung, Eastman ve Svensk Etanolkemi bulunuyor.

Metanol karbonilasyon

En bakir asetik asit, metanol karbonilasyon ile retilir. Bu ilemde, metanol ve karbon monoksit kimyasal denkleme gre asetik asit retmek iin reaksiyona girer:

CH3OH + CO → CH3COOH

lem, bir ara rn olarak iyodometan ierir ve aamada gerekleir. Karbonilasyon iin genellikle bir metal kompleksi olan bir katalizre ihtiya vardr (aama 2). (1) CH3OH + HI → CH3I + H2O (2) CH3I + CO → CH3COI (3) CH3COI + H2O → CH3COOH + HI Proses koullarn deitirerek ayn bitki zerinde asetik anhidrit de retilebilir. Hem metanol hem de karbon monoksit emtia hammaddesi olduundan, metanol karbonilasyonu uzun zamandr asetik asit retimi iin ekici bir yntem olarak ortaya kmtr. ngiliz Celanese`deki Henry Drefyus, 1925 ylna kadar bir metanol karbonilasyon pilot tesisi gelitirdi. [10] Ancak, ihtiya duyulan yksek basnlarda (200 atm veya daha fazla) korozif reaksiyon karmn ierebilecek pratik malzeme eksiklii, bu yollarn bir sredir ticariletirilmesini engellemitir. Bir kobalt katalizr kullanlan ilk ticari metanol karbonilasyon ilemi, 1963 ylnda Alman kimya irketi BASF tarafndan gelitirilmitir. 1968`de, verimli bir ekilde alabilen rodyum bazl bir katalizr (cis- [Rh (CO) 2I2] -) kefedilmitir. neredeyse hi yan rn iermeyen daha dk basn. Bu katalizr kullanan ilk bitki, 1970 ylnda ABD kimya irketi Monsanto tarafndan imal edildi ve rodyum katalizeli metanol karbonilasyonu, asetik asit retiminin baskn yntemi haline geldi (Monsanto prosesine baknz). 1990`larn sonlarnda, kimya irketi BP Chemicals, rutenyum tarafndan tevik edilen Cativa katalizrn ([Ir (CO) 2I2] -) ticariletirdi. Bu iridyum katalizli sre daha yeil ve daha verimli [11] ve ounlukla ayn retim tesislerinde Monsanto srecini byk lde tamamlamtr.

Asetaldehit oksidasyonu

Monsanto ileminin ticariletirilmesinden nce asetik asit, asetaldehitin oksidasyonuyla retildi. Bu, metanol karbonilasyonu ile rekabetsiz olmasna ramen, ikinci en nemli retim yntemi olmaya devam etmektedir. Asetaldehit, btan veya hafif naftann oksidasyonu veya etilenin hidratlanmas yoluyla retilebilir. Btan veya hafif nafta, manganez, kobalt ve kromun da dahil olduu eitli metal iyonlarnn varlnda hava ile stldnda, peroksitler oluur ve daha sonra kimyasal denkleme gre asetik asit retmek zere ayrrlar.

Btan veya hafif nafta, manganez, kobalt ve kromun da dahil olduu eitli metal iyonlarnn varlnda hava ile stldnda, peroksitler oluur ve daha sonra kimyasal denkleme gre asetik asit retmek zere ayrrlar.

2 C4H10 + 5 O2 → 4 CH3COOH + 2 H2O

Tipik olarak, reaksiyon, btan bir sv hl muhafaza ederken mmkn olduunca scak olacak ekilde tasarlanm bir scaklk ve basn kombinasyonunda gerekletirilir. Tipik reaksiyon koullar 150 C ve 55 atm`dir. Butanon, etil asetat, formik asit ve propionik asit dahil olmak zere birok yan rn de oluabilir. Bu yan rnler de ticari olarak deerlidir ve eer bu ekonomik olarak faydal ise daha fazla retmek iin reaksiyon koullar deitirilebilir. Bununla birlikte, asetik asidin bu yan rnlerden ayrlmas, ilemin maliyetine katkda bulunur.

Benzer koullar altnda ve btan oksidasyonu iin kullanlan benzer katalizrleri kullanarak, asetaldehit, asetik asit retmek iin havadaki oksijen tarafndan oksitlenebilir.

2 CH3CHO + O2 → 2 CH3COOH

Modern katalizrleri kullanarak, bu reaksiyon% 95`ten daha byk bir asetik asit verimine sahip olabilir. Ana yan rnler etil asetat, formik asit ve formaldehittir, hepsi asetik asitten daha dk kaynama noktasna sahiptir ve damtma ile kolayca ayrlr.

ETLEN OKSDASYONU

FERMENTASYON

Oksidatif fermantasyon

nsanlk tarihinin ou iin, asetik asit, sirke eklinde, Acetobacter cinsinden bakteriler tarafndan yaplmtr. Yeterli oksijen verildiinde, bu bakteriler eitli alkoll yiyeceklerden sirke retebilir. Yaygn olarak kullanlan yemler arasnda elma arab, arap ve mayalanm tahl, malt, pirin veya patates ezmesi bulunur. Bu bakteriler tarafndan kolaylatrlan genel kimyasal reaksiyon

C2H5OH + O2 → CH3COOH + H2O

Asetamacter ile alanm ve scak, havadar bir yerde tutulan bir seyreltik alkol zeltisi, birka ay boyunca sirke haline gelecektir. Endstriyel sirke yapm yntemleri, bakteriye oksijen tedariki gelitirerek bu sreci hzlandrr.

Fermantasyon ile retilen ilk sirke ynlar, muhtemelen arap yapm srecindeki hatalar takip etti. Eer ok yksek bir scaklkta fermente edilmesi gerekiyorsa, asetobakter, doal olarak zmlerde meydana gelen mayay ezecektir. Mutfak, tbbi ve shhi amalar iin sirke talebi arttka, arap reticileri zmleri olgunlamadan ve araba hazr hale gelmeden nce scak yaz aylarnda sirke retmek iin dier organik malzemeleri kullanmay abucak rendi. Bununla birlikte, bu yntem yavat, ve hakemler sreci anlamad iin her zaman baarl olmad.

lk modern ticari srelerden biri, ilk olarak 1823`te Almanya`da uygulanan “hzl yntem” veya “Alman yntemi” idi. Bu srete fermantasyon, odun tala veya odun kmr ile dolu bir kulede gerekleiyor. Alkol ieren yem, kulenin tepesine ve tabanda doal veya zorlanm konveksiyonla salanan taze havaya damlatlr. Bu ilemde gelitirilmi hava kayna, sirkeyi aylardan haftalara hazrlamak iin zaman ksaltmtr.

Bugn sirkenin ou, 1949 ylnda Otto Hromatka ve Heinrich Ebner tarafndan tanmlanan, batk tank kltrnde yaplmtr. Bu yntemde, alkol srekli olarak kartrlm bir tankta sirke ile fermente edilir ve solsyondan hava kabarcklanarak oksijen salanr. Bu yntemi kullanarak, yzde 15 asetik asit sirkesi sadece iki ila gn iinde hazrlanabilir.

Anaerobik fermantasyon

Clostridium cinsinin birka yesi de dahil olmak zere baz anaerobik bakteri trleri, ara rn olarak etanol kullanmadan dorudan ekerleri asetik aside dntrebilir. Bu bakteriler tarafndan yrtlen genel kimyasal reaksiyon u ekilde temsil edilebilir:

C6H12O6 → 3 CH3COOH

Bir endstriyel kimyacnn bak asndan daha ilgin olarak, bu asetojenik bakterilerin ou, metanol, karbon monoksit veya karbon dioksit ve hidrojen karm gibi tek karbonlu bileiklerden asetik asit retebilir:

2 CO2 + 4 H2 → CH3COOH + 2 H2O

Clostridium`n ekerleri dorudan kullanma veya daha az maliyetli girdilerden asetik asit retme yetenei, bu bakterilerin asetik asidi potansiyel olarak Acetobacter gibi etanol-oksidizrlerden daha verimli retebilecei anlamna gelir. Bununla birlikte, Clostridium bakterileri, Acetobacter`den daha az asit toleransldr. En asit toleransl Clostridium sular bile yzde 20`ye kadar asetik asit sirkesi retebilen baz Asetobacter sularna kyasla, sadece yzde birka asetik asit sirkesi retebilir. u anda, Clostridium kullanarak retmek ve daha sonra konsantre etmek yerine, Acetobacter kullanarak sirke retmek iin daha uygun maliyetli kalr. Sonu olarak, 1940`dan beri asetojenik bakteriler bilinmesine ramen, endstriyel kullanmlar birka ni uygulama ile snrl kalmaktadr.

UYGULAMALAR

Asetik asit, birok kimyasal bileiin retimi iin kimyasal bir reaktiftir. En byk tek asetik asit kullanm, vinil asetat monomeri retimindedir, bunu takiben asetik anhidrit ve ester retimi takip eder. Sirke kullanlan asetik asit hacmi nispeten kktr.

DER UYGULAMALAR

Asetik asitlerin seyreltilmi zeltileri de hafif asitlii iin kullanlr. Ev ortamndaki rnekler arasnda, fotografik filmlerin gelitirilmesi srasnda bir durdurma banyosunda kullanm ve kire zc maddelerde musluk ve su stclarmdan kire pulunu karmak bulunmaktadr. Asitlik ayrca, denizanasnn batma hcrelerini devre d brakarak, hemen uyguland takdirde ciddi yaralanmay veya lm nleyerek ve Vosol gibi mstahzarlardaki insanlarda d kulak enfeksiyonlarn tedavi etmek iin kutu denizanas sokmasnn ilenmesinde kullanlr. Edeer olarak, asetik asit, bakteri ve mantar geliimini engellemek iin canl hayvan silaj iin pskrtmeli bir koruyucu olarak kullanlr.

Buzlu asetik asit de bir siil ve verruca karc olarak kullanlr. Siilin etrafndaki deriye yaylmasn nlemek iin bir halka pellum ya uygulanr ve siil veya verrukaya bir veya iki damla buzlu asetik asit uygulanr. Tedavi gnlk olarak tekrarlanr. Bu yntem arszdr ve dier birok tedavinin aksine yksek bir baar oranna sahiptir. Buzlu asetik asitin emilmesi kk miktarlarda gvenlidir.

Aadakileri ieren asetik asitten birka organik veya inorganik tuz retilir:

Sodyum asetat – tekstil endstrisinde ve gda koruyucu olarak kullanlr (E262).

Bakr (II) asetat – bir pigment ve bir fungisit olarak kullanlr.

Alminyum asetat ve demir (II) asetat – boyalar iin mordan olarak kullanlr.

Palladium (II) asetat – Heck reaksiyonu gibi organik balanma reaksiyonlar iin bir katalizr olarak kullanlr.

retilen ikame edilmi asetik asitler unlar ierir:

Monokloroasetik asit (MCA), dikloroasetik asit (bir yan rn olarak kabul edilir) ve trikloroasetik asit. MCA, indigo boya retiminde kullanlr.

Reaktif etil bromoasetat retmek iin esterlenen Bromoasetik asit.

Organik sentezde ortak bir reaktif olan trifloroasetik asit.

Bu dier uygulamalarda (TPA dnda) kullanlan asetik asit miktarlar, dnya apnda asetik asit kullanmnn yzde 5-10`unu oluturmaktadr. Bununla birlikte, bu uygulamalarn TPA retimi kadar bymemesi beklenmemektedir.

Emniyet

Konsantre asetik asit andrcdr ve bu nedenle cilt yanklar, kalc gz hasar ve mukoza zarnda tahrie neden olabileceinden uygun bakm ile kullanlmaldr. Bu yanklar veya kabarcklar, maruziyetten birka saat sonra ortaya kmayabilir. Lateks eldivenler koruma salamaz, bu yzden bileii kullanrken nitril kauuktan yaplm eldivenler gibi zel olarak dayankl eldivenler giyilmelidir. Konsantre asetik asit, laboratuvarda baz zorluklarla atelenebilir. Ortam scakl 39 C`yi (102 F) aarsa yanc bir risk haline gelir ve bu scakln zerinde hava ile patlayc karmlar oluturabilir (patlayc limitler:% 5.4-16).

Asetik asit zeltilerinin tehlikeleri konsantrasyona baldr.

Acide actique

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Page d`aide sur l`homonymie Actique redirige ici. Pour l`article homophone, voir Asctique.

Acide actique

Formule dveloppe de l`acide actique Reprsentation 3D de l`acide actique

Formule topologique et reprsentation 3D de l`acide actique

Identification

Nom UICPA acide actique

Nom systmatique acide thanoque

Synonymes

acide actique glacial

acide thylique, acide mthanecarboxylique

No CAS 64-19-7

No ECHA 100.000.528

No CE 200-580-7

No RTECS AF1225000

Code ATC G01AD02 S02AA10

DrugBank DB03166

PubChem 176

ChEBI 15366

No E E260

FEMA 2006

SMILES

[Afficher]

InChI

[Afficher]

Apparence liquide incolore, d`odeur cre et fortement vinaigre1.

Proprits chimiques

Formule brute C2H4O2 [Isomres]

Masse molaire5 60,052 0,0025 g/mol

C 40 %, H 6,71 %, O 53,29 %,

pKa 4,76 25 C2

Moment dipolaire 1,70 0,03 D3

Diamtre molculaire 0,442 nm4

Proprits physiques

T fusion 16,64 C6

T bullition 117,9 C6

Solubilit Miscible avec l`eau, l`actone, l`alcool, le benzne, le glycrol, l`ther, le ttrachlorure de carbone; Pratiquement insol. dans le disulfure de carbone2

Totalement miscible l`hexane, au tolune.

Paramtre de solubilit δ 20,7 MPa1/2 (25 C)7;

18,9 J1/2cm-3/2 (25 C)4;

12,4 cal1/2cm-3/28

Masse volumique 1,0492 gcm-3 (liquide,20 C)6

[+]

T d`auto-inflammation 465 C10

Point d`clair 39 C (coupelle ferme)1

Limites d`explosivit dans l`air 5,4-16 %vol1

Pression de vapeur saturante 1,5 kPa 20 C1

[+]

Viscosit dynamique 1,22 mPas 25 C

Point critique 4,53 MPa 319,56 C10

Thermochimie

S0gaz, 1 bar 282,848 Jmol-1K-111

S0liquide, 1 bar 158,0 Jmol-1K-111

ΔfH0gaz -433 kJmol-111

ΔfH0liquide -483,52 kJmol-111

ΔfusH 11,728 kJmol-1 16,75 C11

ΔvapH 23,7 kJmol-1 117,95 C11

Cp 123,1 Jmol-1K-1 (liquide,25 C)

63,44 Jmol-1K-1 (gaz,25 C)11

[+]

PCS 874,2 kJmol-113 (liquide)

PCI -875,16 kJmol-111

Proprits lectroniques

1re nergie d`ionisation 10,65 0,02 eV (gaz)14

Cristallographie

Classe cristalline ou groupe d`espace Pna21 15

Volume 297,27 315

Proprits optiques

Indice de rfraction {displaystyle n_{D}^{20}}n^{ 20 }_{ D } 1,37206

Prcautions

SGH16,17

SGH02 : InflammableSGH05 : Corrosif

Danger

H226, H314, P280, P305, P310, P338, P351,

[+]

SIMDUT18

B3 : Liquide combustibleE : Matire corrosive

B3, E,

[+]

NFPA 704

Symbole NFPA 704

230

Transport

2789

[+]

2790

[+]

cotoxicologie

DL50 3,31 gkg-1 (rat, oral)

525 mgkg-1 (souris, i.v.)19

LogP -0,311

Seuil de l`odorat bas : 0,03 ppm

haut : 0,15 ppm20

Composs apparents

Isomre(s) Glycolaldhyde

Autres composs

Anhydride actique

Units du SI et CNTP, sauf indication contraire.

modifier Consultez la documentation du modle

L`acide actique ou acide thanoque est un acide carboxylique avec une chane carbone thorique en C2, analogue l`thane, de masse molaire 60 g/mol et de formule chimique brute C2H4O2 ou semi-dveloppe CH3-CO-OH. L`adjectif du nom courant provient du latin acetum, signifiant vinaigre. En effet, l`acide actique reprsente le principal constituant du vinaigre aprs l`eau, puisqu`il lui donne son got acide et son odeur piquante dtectable partir d`1 ppm22.

La distillation du vinaigre, atteste ds l`poque mdivale en Europe, a permis d`obtenir l`acide actique pur, liquide combustible incolore forte odeur de vinaigre, de masse volumique de l`ordre d`1,05 gcm-3 20 C qui se solidifie par simple immersion dans un bain eau-glace23. Il est encore connu sous le nom d`acide actique glacial ou autrefois de vinaigre fort. C`est le premier acide industriel connu.

Ce liquide trs faiblement conducteur, incolore, inflammable et hygroscopique reprsente temprature ambiante un des plus simples acides monocarboxyliques, avec l`acide formique. Son acidit caractrise en solution aqueuse par un pKa = 4,76 vient de sa capacit perdre temporairement le proton de sa fonction carboxylique, le transformant ainsi en ion actate CH3COO-. C`est un acide faible.

Cet acide coagule le latex et a des proprits bactriostatiques, ce qui permet de l`utiliser comme dsinfectant. Il est galement utilis comme composant d`insecticides et d`agent de nettoyage pour la fabrication de semi-conducteurs22. Il est corrosif et ses vapeurs sont irritantes pour le nez et les yeux.

Trs corrosif vis–vis des tissus organiques et vivants, il doit tre manipul avec soin. Bien qu`il n`ait pas t jug cancrogne ou dangereux pour l`environnement, il peut causer des brlures ainsi que des dommages permanents la bouche, au nez, la gorge et aux poumons. certaines doses et en co-exposition chronique avec un produit cancrogne, son caractre irritant en fait un promoteur tumoral de tumeurs (bnignes et malignes)22. Ceci a t dmontr exprimentalement chez le rat22.

Dans le corps humain, l`acide actique est normalement produit aprs la consommation d`alcool : l`thanol est converti en actaldhyde qui est alors converti en acide actique sous l`influence de l`enzyme actaldhyde dshydrognase et ensuite en acetyl-coA par la ligase actate-CoA.

Production

La demande mondiale d`acide actique est d`environ 6,5 millions de tonnes par an (Mt/a). Industriellement, il est produit par l`oxydation en phase liquide du n-butane, ou il est rcupr dans la production d`actate de cellulose ou d`alcool polyvinylique.

Usages

C`est un ractif trs utilis dans l`industrie ou les laboratoires notamment :

comme solvant : miscible l`eau et divers solvants organiques tels l`thanol, l`ther dithylique, le glycrol22 mais insoluble dans le disulfure de carbone22, c`est aussi un bon solvant des gommes, rsines, du phosphore, du soufre et d`acides halognohydriques22 ? ;

dans la production d`anhydride actique, actate de cellulose, d`actate de vinyle monomre, et d`autres actates, ainsi que de mdicaments, pesticides, colorants, la fabrication de produits photographiques22 ;

dans l`alimentation (production de vinaigres de fruit22…), additif alimentaire ;

les textiles22 ;

comme agent de nettoyage (de semi-conducteurs22) ;

coagulant (du latex naturel22) ;

bactriostatique (en solution22) ;

dans la fabrication de plastiques tels le polytrphtalate d`thylne (PET) ou l`actate de cellulose, utile la production d`actate de vinyle (peintures, adhsifs) et de solvants organiques ;

comme additif dans les produits drivs du tabac (arme).

mordanage lors de colorations de coupes histologiques (ex : coloration au carmino-vert)

processus d`hydrolyse24, de condensation24 et/ou de glification pour la fabrication de catalyseur ou lors du procd sol-gel25

antibactrien et acidification gastrique dans l`levage notamment porcin26.

Nomenclature

Le nom trivial ancien, acide actique, drive d`acetum, mot latin qui dsigne le vinaigre ou aceti-vinum. Il est encore le plus utilis dans l`espace francophone et anglophone mais l`IUPAC a normalis le terme acide thanoque, la place de l`ancien nom chimique franais acide thylique. Plus tolrant que la nomenclature IUPAC en 1960, les Chemical Abstracts ont conserv nanmoins les noms courants pour les deux premiers acides carboxyliques en C1 et C2, soit l`acide formique et l`acide actique.

Acide actique glacial reste aussi un nom trivial qui dsigne communment l`acide actique pur au laboratoire. Similaire au nom allemand Eisessig (littralement : vinaigre glac), ce nom s`explique par les cristaux d`acide actique semblables de la glace qui se forment une temprature lgrement infrieure la temprature ambiante ( moins de 17 C, temprature de fusion de l`acide actique pur).

L`abrviation la plus courante pour l`acide actique est AcOH ou HOAc, Ac dsignant le groupe fonctionnel actyle CH3-CO-.

La formule brute de l`acide actique est C2H4O2. On l`crit galement souvent CH3COOH ou CH3CO2H afin de mieux traduire sa structure. L`ion rsultant de la perte du proton H+ porte le nom d`actate. Actate peut galement faire rfrence un sel contenant cet anion ou un ester de l`acide actique.

Historique

Acide actique cristallis

Le vinaigre fort est connu en Msopotamie il y a plus de 3 000 ans av. J.-C.27. Les bactries actiques produisant l`acide actique partir du vin et d`oxygne ont t dcrites par le chimiste Louis Pasteur. Elles sont prsentes partout dans le monde civilis, et toute culture pratiquant le brassage de la bire ou du vin a invitablement dcouvert le vinaigre, rsultat naturel de l`volution de ces boissons alcoolises laisses l`air libre.

L`usage de l`acide actique en chimie remonte l`Antiquit. Au iiie sicle av. J.-C., le philosophe grec Thophraste dcrit comment le vinaigre agit sur le mtal et produit ainsi des pigments utiles pour l`art, incluant le plomb blanc (carbonate de plomb) et vert-de-gris, un mlange vert de sels de cuivre incluant l`actate de cuivre II (tous produits toxiques). Les anciens Romains faisaient bouillir le vin aigre dans des rcipients de plomb pour produire un sirop trs sucr appel sapa. Le sapa tait riche en actate de plomb, une substance sucre appele sucre de plomb ou sucre de Saturne, et qui provoqua de nombreux empoisonnements au plomb dans l`aristocratie romaine, la maladie correspondant une intoxication aigu ou chronique par le plomb est notamment nomme saturnisme. L`alchimiste perse Jabir Ibn Hayyan (Geber) concentra l`acide actique partir du vinaigre par distillation[rf. ncessaire].

Durant la Renaissance, l`acide actique glacial tait prpar par distillation sche d`actates de mtal. Au xvie sicle, l`alchimiste allemand Andreas Libavius en dcrivit la procdure, et compara l`acide pur ainsi produit au vinaigre. La prsence d`eau dans le vinaigre a tant d`influence sur les proprits de l`acide actique que pendant des sicles de nombreux chimistes ont cru que l`acide actique glacial et l`acide prsent dans le vinaigre taient deux substances diffrentes. C`est le chimiste franais Pierre Auguste Adet qui prouva qu`ils taient le mme compos chimique.

En 1847, le chimiste allemand Hermann Kolbe synthtisa l`acide actique partir de matires inorganiques pour la premire fois. La squence de cette raction consistait en la chloration de disulfure de carbone en ttrachloromthane, suivie d`une pyrolyse en ttrachlorothylne, puis d`une chloration aqueuse en acide trichloroactique, et enfin conclure par une rduction par lectrolyse pour obtenir l`acide actique28.

Vers 1910, la majorit de l`acide actique glacial tait obtenue partir de la liqueur pyroligneuse issue de la distillation du bois27. L`acide actique tait isol grce un traitement l`hydroxyde de calcium, et l`actate de calcium ainsi obtenu tait alors acidifi par un ajout d`acide sulfurique pour reformer l`acide actique. L`Allemagne en produisait l`poque 10 000 tonnes par an, dont 30 % tait utilis pour la production de colorant indigo29,30.

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