Acetic acid, also known as ethanoic acid, has a
molecular formula CH3COOH. It is a weak monoprotic acid which is
able to lose a proton from its acid functional group (-COOH) readily and
produce a conjugate base, acetate anion. Acetic acid is also a polar protic
solvent as it dissolves readily and is miscible in other polar solvents such as
water. However, its polar nature makes it insoluble and immiscible in non-polar
solvents such as octane. Using acetic acid as a starting reagent, it readily
forms other organic reagents such as acetyl chloride and ethanol though
substitution and reduction reactions respectively. Acetic acid can also corrode
metals such as iron, magnesium and zinc, forming hydrogen gas and metal
acetates. But since aluminum forms a protective layer of aluminum oxide on its
surface, it is acid-resistance and hence aluminum tanks are used as an option
to transport acetic acid. Alternatively, high-density polyethylene (HDPE) drums
can also be used to transport acetic acids as due to their resistivity.
Acetic acid is
manufactured via carbonylation of methanol. Metal carbonyl is added to methanol
via rhodium-catalyzed Monsanto process or iridium-catalyzed Cativa process.
However, with the introduction of iridium-catalyzed Cativa process, Monsanto
process became obsoleted. Due to the economical and environmental friendliness,
Cativa process soon became the main process used to manufacture acetic acid.
Acetic acid is also
manufactured via acetaldehyde oxidation, where oxidizing butane and hydrating
ethylene via Wacker process obtain acetaldehyde. This crude acetaldehyde is
purified by extractive distillation, followed by fractional distillation. This
acetaldehyde will further oxidize to acetic acid.
Fermentation and Anaerobic Fermentation
Acetic acid can also be
manufactured via oxidative fermentation using acetic acid bacteria Acetobacter
in alcoholic content, and via anaerobic fermentation using anaerobic bacteria
Acetobacterium. The Acetobacter method remains more cost effective to produce
In the food industry,
acetic acid is used as an acidity regulator and as a condiment. Acetic acid is also used as a main ingredient for
vinegar production. In food industry, acetic acid is also used as an
antimicrobial and additives.
Acetic acid is used as a
polar protic organic solvent for recrystallization and the production of
purified terephthalic acid (PTA). This serves as a precursor and is in turn
used to manufacture polyethylene terephthalate (PET), which is used to make
clothing and plastics.
Acetic acid helps in the
breaking down of starches and sugars in table sugar, as well as sugar in milk.
It is also used to manufacture vinyl acetate monomer, acetic anhydride and
acetate ester, as well as purified terephthalic acid. In addition, Acetic acids are widely used for textile processing and
printing. Acetic acids are used to synthesize acetic anhydride that serves
as an acetylation agent and its major application is for cellulose