Acetic acid

Nomenclature				prepare vinegar from months to weeks.
The trivial name acetic acid derives from acetum, the				Most vinegar today[when?] is made in submerged tank
Latin word for vinegar, and is related to the word acid				culture, first described in 1949 by Otto Hromatka and
itself. The synonym ethanoic acid is constructed				Heinrich Ebner. In this method, alcohol is fermented to
according to the substitutive nomenclature of the				vinegar in a continuously stirred tank, and oxygen is
IUPAC.				supplied by bubbling air through the solution. Using
Glacial acetic acid is a trivial name for water-free				modern applications of this method, vinegar of 15%
acetic acid. Similar to the German name Eisessig				acetic acid can be prepared in only 24 hours in batch
(literally, ice-vinegar), the name comes from the ice-like				process, even 20% in 60 hour fed-batch process.
crystals that form slightly below room temperature at				Anaerobic fermentation
16.7 C (62 F).				Species of anaerobic bacteria, including members of
The most common abbreviation for acetic acid is				the genus Clostridium, can convert sugars to acetic
HOAc where Ac stands for the acetyl group				acid directly, without using ethanol as an intermediate.
CH3(=O). In the context of acid-base reactions the				The overall chemical reaction conducted by these
abbreviation HAc is often used where Ac instead				bacteria may be represented as:
stands for the acetate anion (CH3COO, abbreviated				C6H12O6 3 CH3COOH
AcO), although this use is regarded by many as				More interestingly from the point of view of an
misleading. In either case, the Ac is not to be confused				industrial chemist, these acetogenic bacteria can
with the abbreviation for the chemical element actinium.				produce acetic acid from one-carbon compounds,
Acetic acid has the empirical formula CH2O. To				including methanol, carbon monoxide, or a mixture of
emphasize the role of the active hydrogen in forming				carbon dioxide and hydrogen:
the salt sodium acetate, some people write the				2 CO2 + 4 H2 CH3COOH + 2 H2O
molecular formula as C2H4O2 or HC2H3O2. To better				This ability of Clostridium to utilize sugars directly, or to
reflect its structure, acetic acid is often written as				produce acetic acid from less costly inputs, means that
CH3-CO2-H, CH3COOH, or CH3CO2H. The ion				these bacteria could potentially produce acetic acid
resulting from loss of H+ from acetic acid is the				more efficiently than ethanol-oxidizers like Acetobacter.
acetate anion. The name acetate can also refer to a				However, Clostridium bacteria are less acid-tolerant
salt containing this anion, or an ester of acetic acid.				than Acetobacter. Even the most acid-tolerant
History				Clostridium strains can produce vinegar of only a few
Vinegar was known, early in civilization, as the natural				per cent acetic acid, compared to Acetobacter strains
result of air exposure of beer and wine, as acetic				that can produce vinegar of up to 20% acetic acid. At
acid-producing bacteria are present throughout the				present, it remains more cost-effective to produce
world. The use of acetic acid in alchemy extends into				vinegar using Acetobacter than to produce it using
the third century BC, when the Greek philosopher				Clostridium and then concentrating it. As a result,
Theophrastus described how vinegar acted on metals				although acetogenic bacteria have been known since
to produce pigments useful in art, including white lead				1940, their industrial use remains confined to a few
(lead carbonate) and verdigris, a green mixture of				niche applications.
copper salts including copper(II) acetate. Ancient				Applications
Romans boiled soured wine in lead pots to produce a				2.5-litre bottle of acetic acid in a laboratory.
highly sweet syrup called sapa. Sapa was rich in lead				Acetic acid is a chemical reagent for the production of
acetate, a sweet substance also called sugar of lead				chemical compounds. The largest single use of acetic
or sugar of Saturn, which contributed to lead poisoning				acid is in the production of vinyl acetate monomer,
among the Roman aristocracy.				closely followed by acetic anhydride and ester
In the 8th century the Muslim alchemist Jabir Ibn				production. The volume of acetic acid used in vinegar
Hayyan (Geber) was the first to concentrate acetic				is comparatively small.
acid from vinegar through distillation. In the				Vinyl acetate monomer
Renaissance, glacial acetic acid was prepared through				The major use of acetic acid is for the production of
the dry distillation of certain metal acetates (most				vinyl acetate monomer (VAM). This application
noticeably copper(II) acetate). The 16th century				consumes approximately 40% to 45% of the world's
German alchemist Andreas Libavius described such a				production of acetic acid. The reaction is of ethylene
procedure, and he compared the glacial acetic acid				and acetic acid with oxygen over a palladium catalyst.
produced by this means to vinegar. The presence of				2 H3C-COOH + 2 C2H4 + O2 2 H3C-CO-O-CH=CH2
water in vinegar has such a profound effect on acetic				+ 2 H2O
acid's properties that for centuries chemists believed				Vinyl acetate can be polymerized to polyvinyl acetate
that glacial acetic acid and the acid found in vinegar				or to other polymers, which are applied in paints and
were two different substances. The French chemist				adhesives.
Pierre Adet proved them to be identical.				Ester production
Crystallized acetic acid				The major esters of acetic acid are commonly used
In 1847 the German chemist Hermann Kolbe				solvents for inks, paints and coatings. The esters
synthesized acetic acid from inorganic materials for				include ethyl acetate, n-butyl acetate, isobutyl acetate,
the first time. This reaction sequence consisted of				and propyl acetate. They are typically produced by
chlorination of carbon disulfide to carbon tetrachloride,				catalysed reaction from acetic acid and the
followed by pyrolysis to tetrachloroethylene and				corresponding alcohol:
aqueous chlorination to trichloroacetic acid, and				H3C-COOH + HO-R H3C-CO-O-R + H2O, (R = a
concluded with electrolytic reduction to acetic acid.				general alkyl group)
By 1910 most glacial acetic acid was obtained from the				Most acetate esters, however, are produced from
"pyroligneous liquor" from distillation of wood. The				acetaldehyde using the Tishchenko reaction.
acetic acid was isolated from this by treatment with				Additionally, ether acetates are used as solvents for
milk of lime, and the resultant calcium acetate was				nitrocellulose, acrylic lacquers, varnish removers and
then acidified with sulfuric acid to recover acetic acid.				wood stains. First glycol monoethers are produced
At that time Germany was producing 10,000 tons of				from ethylene oxide or propylene oxide with alcohol,
glacial acetic acid, around 30% of which was used for				which are then esterified with acetic acid. The three
the manufacture of indigo dye.				major products are ethylene glycol monoethyl ether
Chemical properties				acetate (EEA), ethylene glycol monobutyl ether
Acetic acid crystals				acetate (EBA), and propylene glycol monomethyl ether
The hydrogen (H) atom in the carboxyl group (OOH) in				acetate (PMA). This application consumes about 15%
carboxylic acids such as acetic acid can be given off				to 20% of worldwide acetic acid. Ether acetates, for
as an H+ ion (proton), giving them their acidic character.				example EEA, have been shown to be harmful to
Acetic acid is a weak, effectively monoprotic acid in				human reproduction.
aqueous solution, with a pKa value of 4.75. Its				Acetic anhydride
conjugate base is acetate (CH3COO). A 1.0 M				The condensation product of two molecules of acetic
solution (about the concentration of domestic vinegar)				acid is acetic anhydride. The worldwide production of
has a pH of 2.4, indicating that merely 0.4% of the				acetic anhydride is a major application, and uses
acetic acid molecules are dissociated.				approximately 25% to 30% of the global production of
Cyclic dimer of acetic acid; dashed lines represent				acetic acid. Acetic anhydride may be produced directly
hydrogen bonds				by methanol carbonylation bypassing the acid, and
The crystal structure of acetic acid shows that the				Cativa production plants can be adapted for anhydride
molecules pair up into dimers connected by hydrogen				production.
bonds. The dimers can also be detected in the vapour				Acetic anhydride is a strong acetylation agent. As
at 120 C. They also occur in the liquid phase in dilute				such, its major application is for cellulose acetate, a
solutions in non-hydrogen-bonding solvents, and a				synthetic textile also used for photographic film. Acetic
certain extent in pure acetic acid, but are disrupted by				anhydride is also a reagent for the production of
hydrogen-bonding solvents. The dissociation enthalpy				aspirin, heroin, and other compounds.
of the dimer is estimated at 65.066.0 kJ/mol, and the				Vinegar
dissociation entropy at 154157 J mol1 K1. This				In the form of vinegar, acetic acid solutions (typically
dimerization behaviour is shared by other lower				4% to 18% acetic acid, with the percentage usually
carboxylic acids.				calculated by mass) are used directly as a condiment,
Liquid acetic acid is a hydrophilic (polar) protic solvent,				and also in the pickling of vegetables and other
similar to ethanol and water. With a moderate relative				foodstuffs. Table vinegar tends to be more diluted (4%
static permittivity (dielectric constant) of 6.2, it can				to 8% acetic acid), while commercial food pickling
dissolve not only polar compounds such as inorganic				generally employs more concentrated solutions. The
salts and sugars, but also non-polar compounds such				amount of acetic acid used as vinegar on a worldwide
as oils and elements such as sulfur and iodine. It readily				scale is not large, but historically this is by far the oldest
mixes with other polar and non-polar solvents such as				and most well-known application. Tapato hot sauce is
water, chloroform, and hexane. With higher alkanes				an example of a product that combines acetic acid
(starting with octane) acetic acid is not completely				and water to create vinegar in the production of the
miscible anymore. The miscibility gap is becoming larger				food product.
with longer n-alkanes. This dissolving property and				Use as solvent
miscibility of acetic acid makes it a widely used				Glacial acetic acid is an excellent polar protic solvent,
industrial chemical.				as noted above. It is frequently used as a solvent for
Chemical reactions				recrystallization to purify organic compounds. Pure
Acetic acid is corrosive to metals including iron,				acetic acid is used as a solvent in the production of
magnesium, and zinc, forming hydrogen gas and metal				terephthalic acid (TPA), the raw material for
salts called acetates. Aluminium, when exposed to				polyethylene terephthalate (PET). Although
oxygen, forms a thin layer of aluminium oxide on its				currently[when?] accounting for 510% of acetic acid
surface which is relatively resistant to the acid, this				use worldwide, this specific application is expected to
allows aluminium tanks to transport acetic acid. Metal				grow significantly in the next decade, as PET
acetates can also be prepared from acetic acid and				production increases.
an appropriate base, as in the popular "baking soda +				Acetic acid is often used as a solvent for reactions
vinegar" reaction. With the notable exception of				involving carbocations, such as Friedel-Crafts alkylation.
chromium(II) acetate, almost all acetates are soluble in				For example, one stage in the commercial
water.				manufacture of synthetic camphor involves a
Mg(s) + 2 CH3COOH(aq) (CH3COO)2Mg(aq) + H2(g)				Wagner-Meerwein rearrangement of camphene to
NaHCO3(s) + CH3COOH(aq) CH3COONa(aq) +				isobornyl acetate; here acetic acid acts both as a
CO2(g) + H2O(l)				solvent and as a nucleophile to trap the rearranged
Acetic acid undergoes the typical chemical reactions				carbocation. Acetic acid is the solvent of choice when
of a carboxylic acid, such as producing water and a				reducing an aryl nitro-group to an aniline using
metal ethanoate when reacting with alkalis, producing a				palladium-on-carbon.
metal ethanoate when reacted with a metal, and				Glacial acetic acid is used in analytical chemistry for
producing a metal ethanoate, water and carbon				the estimation of weakly alkaline substances such as
dioxide when reacting with carbonates and				organic amides. Glacial acetic acid is a much weaker
hydrogencarbonates. Most notable of all its reactions is				base than water, so the amide behaves as a strong
the formation of ethanol by reduction, and formation of				base in this medium. It then can be titrated using a
derivatives such as acetyl chloride via nucleophilic acyl				solution in glacial acetic acid of a very strong acid, such
substitution. Other substitution derivatives include acetic				as perchloric acid.
anhydride; this anhydride is produced by loss of water				Other applications
from two molecules of acetic acid. Esters of acetic				Dilute solutions of acetic acids are also used for their
acid can likewise be formed via Fischer esterification,				mild acidity. Examples in the household environment
and amides can also be formed. When heated above				include the use in a stop bath during the development
440 C, acetic acid decomposes to produce carbon				of photographic films, and in descaling agents to
dioxide and methane, or to produce ethenone and				remove limescale from taps and kettles.
water.				Dilute solutions of glacial acetic acid can be used in the
Acetic acid can be detected by its characteristic smell.				clinical laboratory to lyse red blood cells in order to do
A colour reaction for salts of acetic acid is iron(III)				manual white blood cell counts. Another clinical use is
chloride solution, which results in a deeply red colour				for lysing red blood cells which can obscure other
that disappears after acidification. Acetates when				important constituents in urine during a microscopic
heated with arsenic trioxide form cacodyl oxide, which				examination.
can be detected by its malodorous vapours.				The acidity is also used for treating the sting of the
Biochemistry				box jellyfish by disabling the stinging cells of the jellyfish,
The acetyl group, derived from acetic acid, is				preventing serious injury or death if applied immediately,
fundamental to the biochemistry of virtually all forms of				and for treating outer ear infections in people in
life. When bound to coenzyme A it is central to the				preparations such as Vosol. Equivalently, acetic acid is
metabolism of carbohydrates and fats. However, the				used as a spray-on preservative for livestock silage, to
concentration of free acetic acid in cells is kept at a				discourage bacterial and fungal growth. Glacial acetic
low level to avoid disrupting the control of the pH of				acid is also used as a wart and verruca remover.
the cell contents. Unlike longer-chain carboxylic acids				Organic or inorganic salts are produced from acetic
(the fatty acids), acetic acid does not occur in natural				acid, including:
triglycerides. However, the artificial triglyceride triacetin				Sodium acetate, used in the textile industry and as a
(glycerin triacetate) is a common food additive, and is				food preservative (E262).
found in cosmetics and topical medicines.				Copper(II) acetate, used as a pigment and a fungicide.
Acetic acid is produced and excreted by acetic acid				Aluminium acetate and iron(II) acetatesed as mordants
bacteria, notably the Acetobacter genus and				for dyes.
Clostridium acetobutylicum. These bacteria are found				Palladium(II) acetate, used as a catalyst for organic
universally in foodstuffs, water, and soil, and acetic acid				coupling reactions such as the Heck reaction.
is produced naturally as fruits and other foods spoil.				Silver acetate, used as a pesticide.
Acetic acid is also a component of the vaginal				Substituted acetic acids produced include:
lubrication of humans and other primates, where it				Monochloroacetic acid (MCA), dichloroacetic acid
appears to serve as a mild antibacterial agent.				(considered a by-product), and trichloroacetic acid.
Production				MCA is used in the manufacture of indigo dye.
Purification and concentration plant for acetic acid in				Bromoacetic acid, which is esterified to produce the
1884				reagent ethyl bromoacetate.
Acetic acid is produced both synthetically and by				Trifluoroacetic acid, which is a common reagent in
bacterial fermentation. Today[when?], the biological				organic synthesis.
route accounts for only about 10% of world production,				Amounts of acetic acid used in these other
but it remains important for vinegar production, as				applications together (apart from TPA) account for
many nations' food purity laws stipulate that vinegar				another 510% of acetic acid use worldwide. These
used in foods must be of biological origin. About 75%				applications are, however, not expected to grow as
of acetic acid made for use in the chemical industry is				much as TPA production. Diluted acetic acid is also
made by methanol carbonylation, explained below.				used in physical therapy to break up nodules of scar
Alternative methods account for the rest. Total				tissue via iontophoresis.
worldwide production of virgin acetic acid is estimated				Safety
at 5 Mt/a (million tonnes per year), approximately half				Concentrated acetic acid is corrosive and must
of which is produced in the United States. European				therefore be handled with appropriate care, since it
production stands at approximately 1 Mt/a and is				can cause skin burns, permanent eye damage, and
declining, and 0.7 Mt/a is produced in Japan. Another				irritation to the mucous membranes. These burns or
1.5 Mt are recycled each year, bringing the total world				blisters may not appear until hours after exposure.
market to 6.5 Mt/a. The two biggest producers of				Latex gloves offer no protection, so specially resistant
virgin acetic acid are Celanese and BP Chemicals.				gloves, such as those made of nitrile rubber, should be
Other major producers include Millennium Chemicals,				worn when handling the compound. Concentrated
Sterling Chemicals, Samsung, Eastman, and Svensk				acetic acid can be ignited with difficulty in the
Etanolkemi.				laboratory. It becomes a flammable risk if the ambient
Methanol carbonylation				temperature exceeds 39 C (102 F), and can form
Most virgin acetic acid is produced by methanol				explosive mixtures with air above this temperature
carbonylation. In this process, methanol and carbon				(explosive limits: 5.416%).
monoxide react to produce acetic acid according to				The hazards of solutions of acetic acid depend on the
the chemical equation:				concentration. The following table lists the EU
CH3OH + CO CH3COOH				classification of acetic acid solutions:
The process involves iodomethane as an intermediate,				Safety symbol
and occurs in three steps. A catalyst, usually a metal				Concentrationby weight
complex, is needed for the carbonylation (step 2).				Molarity
CH3OH + HI CH3I + H2O				Classification
CH3I + CO CH3COI				R-Phrases
CH3COI + H2O CH3COOH + HI				1025%
By altering the process conditions, acetic anhydride				1.674.16 mol/L
may also be produced on the same plant. Because				Irritant (Xi)
both methanol and carbon monoxide are commodity				R36/38
raw materials, methanol carbonylation long appeared				2590%
to be an attractive method for acetic acid production.				4.1614.99 mol/L
Henry Drefyus at British Celanese developed a				Corrosive (C)
methanol carbonylation pilot plant as early as 1925.				R34
However, a lack of practical materials that could				>90%
contain the corrosive reaction mixture at the high				>14.99 mol/L
pressures needed (200 atm or more) discouraged				Corrosive (C) Flammable (F)
commercialization of these routes. The first				R10, R35
commercial methanol carbonylation process, which				Solutions at more than 25% acetic acid are handled in
used a cobalt catalyst, was developed by German				a fume hood because of the pungent, corrosive
chemical company BASF in 1963. In 1968, a				vapour. Dilute acetic acid, in the form of vinegar, is
rhodium-based catalyst (cisRh(CO)2I2]) was				harmless. However, ingestion of stronger solutions is
discovered that could operate efficiently at lower				dangerous to human and animal life. It can cause
pressure with almost no by-products. The first plant				severe damage to the digestive system, and a
using this catalyst was built by US chemical company				potentially lethal change in the acidity of the blood.
Monsanto Company in 1970, and rhodium-catalysed				Due to incompatibilities, it is recommended to keep
methanol carbonylation became the dominant method				acetic acid away from chromic acid, ethylene glycol,
of acetic acid production (see Monsanto process). In				nitric acid, perchloric acid, permanganates, peroxides
the late 1990s, the chemicals company BP Chemicals				and hydroxyls.
commercialized the Cativa catalyst ([Ir(CO)2I2]), which				See also
is promoted by ruthenium. This iridium-catalysed Cativa				Acetyl group, the CH3-CO group, abbreviated Ac
process is greener and more efficient and has largely				Acids in wine
supplanted the Monsanto process, often in the same				Common chemicals, where to purchase common
production plants.				chemicals used in experiments
Acetaldehyde oxidation				Sodium citrate
Prior to the commercialization of the Monsanto				References
process, most acetic acid was produced by oxidation				^ Akeroyd, F. Michael (1993). "Laudan's Problem Solving
of acetaldehyde. This remains the second most				Model". The British Journal for the Philosophy of
important manufacturing method, although it is				Science 44 (4): 78588. doi:10.1093/bjps/44.4.785.
uncompetitive with methanol carbonylation.				^ a b c Martin, Geoffrey (1917). Industrial and
The acetaldehyde may be produced via oxidation of				Manufacturing Chemistry (Part 1, Organic ed.). London:
butane or light naphtha, or by hydration of ethylene.				Crosby Lockwood. pp. 33031.
When butane or light naphtha is heated with air in the				^ Goldwhite, Harold (September 2003). "Short
presence of various metal ions, including those of				summary of the career of the German organic
manganese, cobalt and chromium; peroxides form and				chemist, Hermann Kolbe" (PDF). New Haven Section
then decompose to produce acetic acid according to				Bull. Am. Chem. Soc. 20 (3).
the chemical equation				^ Schweppe, Helmut (1979). "Identification of dyes on
2 C4H10 + 5 O2 4 CH3COOH + 2 H2O				old textiles". J. Am. Inst. Conservation 19 (1/3): 1423.
Typically, the reaction is run at a combination of				doi:10.2307/3179569.
temperature and pressure designed to be as hot as				^ Jones, R.E.; Templeton, D.H. (1958). "The crystal
possible while still keeping the butane a liquid. Typical				structure of acetic acid". Acta Crystallogr. 11 (7): 48487.
reaction conditions are 150 C and 55 atm. Side				doi:10.1107/S0365110X58001341.
products may also form, including butanone, ethyl				^ Briggs, James M.; Toan B. Nguyen, William L.
acetate, formic acid, and propionic acid. These side				Jorgensen (1991). "Monte Carlo simulations of liquid
products are also commercially valuable, and the				acetic acid and methyl acetate with the OPLS
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them if this is economically useful. However, the				doi:10.1021/j100161a065.
separation of acetic acid from these by-products adds				^ Togeas, James B. (2005). "Acetic Acid Vapor: 2. A
to the cost of the process.				Statistical Mechanical Critique of Vapor Density
Under similar conditions and using similar catalysts as				Experiments". J. Phys. Chem. A 109 (24): 5438.
are used for butane oxidation, acetaldehyde can be				doi:10.1021/jp058004j. PMID 16839071.
oxidized by the oxygen in air to produce acetic acid				^ Zieborak, K.; K. Olszewski (1958).
2 CH3CHO + O2 2 CH3COOH				Bull.Acad.Pol.Sci.Ser.Sci.Chim.Geol.Geogr. 6 (2): 331522.
Using modern catalysts, this reaction can have an				^ executive ed.: J. Buckingham (1996). Dictionary of
acetic acid yield greater than 95%. The major side				Organic Compounds. 1 (6th ed.). London: Chapman
products are ethyl acetate, formic acid, and				& Hall. ISBN 0-412-54090-8.
formaldehyde, all of which have lower boiling points				^ Yoneda, N.; Kusano, S.; Yasui, M.; Pujado, P.; Wilcher,
than acetic acid and are readily separated by distillation.				S. (2001). "Recent advances in processes and
Ethylene oxidation				catalysts for the production of acetic acid". Applied
Acetaldehyde may be prepared from ethylene via the				Catalysis A, General 221 (1-2): 253265. doi:10.1016
Wacker process, and then oxidized as above. More				S0926-860X(01)00800-6.
recently a cheaper single-stage conversion of ethylene				^ "Production report". Chem. Eng. News: 6776. 11 July
to acetic acid was commercialized by chemical				2005.
company Showa Denko, which opened an ethylene				^ a b c d e Suresh, Bala (2003). "Acetic Acid".
oxidation plant in ita, Japan, in 1997. The process is				Chemicals Economic Handbook. SRI International.
catalysed by a palladium metal catalyst supported on				pp. 602.5000.
a heteropoly acid such as tungstosilicic acid. It is				^ Wagner, Frank S. (1978). "Acetic acid". in Grayson,
thought to be competitive with methanol carbonylation				Martin. Kirk-Othmer Encyclopedia of Chemical
for smaller plants (100250 kt/a), depending on the local				Technology (3rd ed.). New York: John Wiley &
price of ethylene.				Sons.
Oxidative fermentation				^ Lancaster, Mike (2002). Green Chemistry, an
For most of human history, acetic acid, in the form of				Introductory Text. Cambridge: Royal Society of
vinegar, has been made by acetic acid bacteria of the				Chemistry. pp. 26266. ISBN 0-85404-620-8.
genus Acetobacter. Given sufficient oxygen, these				^ "Acetic acid". National Institute of Standards and
bacteria can produce vinegar from a variety of				Technology. Retrieved 2008-02-03.
alcoholic foodstuffs. Commonly used feeds include				^ Sano, Ken-ichi; Uchida, Hiroshi; Wakabayashi,
apple cider, wine, and fermented grain, malt, rice, or				Syoichirou (1999). A new process for acetic acid
potato mashes. The overall chemical reaction				production by direct oxidation of ethylene. 3. 6660.
facilitated by these bacteria is:				doi:10.1023/A:1019003230537.
C2H5OH + O2 CH3COOH + H2O				^ a b Otto Hromatka and Heinrich Ebner (1959).
A dilute alcohol solution inoculated with Acetobacter				"Vinegar by Submerged Oxidative Fermentation". Ind.
and kept in a warm, airy place will become vinegar				Eng. Chem. 51 (10): 1279 1280. doi:10.1021/ie50598a033.
over the course of a few months. Industrial				^ Everett P. Partridge (1931). "Acetic Acid and Cellulose
vinegar-making methods accelerate this process by				Acetate in the United States A General Survey of
improving the supply of oxygen to the bacteria.				Economic and Technical Developments". Ind. Eng.
The first batches of vinegar produced by fermentation				Chem. 23 (5): 482 498. doi:10.1021/ie50257a005.
probably followed errors in the winemaking process. If				^ O Hromatka, H Ebner (1949). "Investigations on
must is fermented at too high a temperature,				vinegar fermentation: Generator for vinegar
acetobacter will overwhelm the yeast naturally				fermentation and aeration procedures". Enzymologia 13:
occurring on the grapes. As the demand for vinegar				369.
for culinary, medical, and sanitary purposes increased,				^ Jia Huey Sim, Azlina Harun Kamaruddin, Wei Sing
vintners quickly learned to use other organic materials				Long and Ghasem Najafpour (2007). "Clostridium
to produce vinegar in the hot summer months before				aceticum potential organism in catalyzing carbon
the grapes were ripe and ready for processing into				monoxide to acetic acid: Application of response
wine. This method was slow, however, and not always				surface methodology". Enzyme and Microbial
successful, as the vintners did not understand the				Technology 40 (5): 12341243. doi:10.1016
process.				j.enzmictec.2006.09.017.
One of the first modern commercial processes was				External links
the "fast method" or "German method", first practiced				Wikimedia Commons has media related to: Acetic acid
in Germany in 1823. In this process, fermentation takes				International Chemical Safety Card 0363
place in a tower packed with wood shavings or				National Pollutant Inventory - Acetic acid fact sheet
charcoal. The alcohol-containing feed is trickled into the				NIOSH Pocket Guide to Chemical Hazards
top of the tower, and fresh air supplied from the				Method for sampling and analysis
bottom by either natural or forced convection. The				29 CFR 1910.
improved air supply in this process cut the time to

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Acetic acid

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