OverviewBrief OverviewAcetic acid, also known as ethanoic acid, has amolecular formula CH3COOH.
It is a weak monoprotic acid which isable to lose a proton from its acid functional group (-COOH) readily andproduce a conjugate base, acetate anion. Acetic acid is also a polar proticsolvent as it dissolves readily and is miscible in other polar solvents such aswater. However, its polar nature makes it insoluble and immiscible in non-polarsolvents such as octane. Using acetic acid as a starting reagent, it readilyforms other organic reagents such as acetyl chloride and ethanol throughsubstitution and reduction reactions respectively. Acetic acid can also corrodemetals such as iron, magnesium and zinc, forming hydrogen gas and metalacetates. But since aluminium forms a protective layer of aluminium oxide onits surface, it is acid-resistance and hence aluminium tanks are used as anoption to transport acetic acid.
Alternatively, high-density polyethylene(HDPE) drums can also be used to transport acetic acids as due to theirresistivity.ManufacturingProcessCarbonylationof MethanolAceticacid is manufactured via carbonylation of methanol. Metal carbonyl is added tomethanol via rhodium-catalyzed Monsanto process or iridium-catalyzed Cativaprocess. However, with the introduction of iridium-catalyzed Cativa process,Monsanto process became obsolete. Due to the economic and environmentalfriendliness, Cativa process soon became the main process used to manufactureacetic acid.AcetaldehydeOxidationAceticacid is also manufactured via acetaldehyde oxidation, where oxidizing butaneand hydrating ethylene via Wacker process obtain acetaldehyde.
This crudeacetaldehyde is purified by extractive distillation, followed by fractionaldistillation. This acetaldehyde will further oxidize to form acetic acid.OxidativeFermentation and Anaerobic FermentationAceticacid can also be manufactured via oxidative fermentation using acetic acidbacteria Acetobacter in alcoholic content, and via anaerobic fermentation usinganaerobic bacteria Acetobacterium. The Acetobacter method remains more cost-effectiveto produce acetic acid.FoodIndustryIn thefood industry, acetic acid is used as an acidity regulator and as a condiment.
Aceticacid is also used as the main ingredient for vinegar production. In the foodindustry, acetic acid is also used as an antimicrobial and additives.IntermediateChemicalsAceticacid is used as a polar protic organic solvent for recrystallization and theproduction of purified terephthalic acid (PTA).
This serves as a precursor andis in turn used to manufacture polyethylene terephthalate (PET), which is usedto make clothing and plastics.OtherApplicationsAceticacid helps in the breaking down of starches and sugars in table sugar, as wellas sugar in milk. It is also used to manufacture vinyl acetate monomer, aceticanhydride and acetate ester, as well as purified terephthalic acid.
Inaddition, Acetic acids are widely used for textile processing andprinting. Acetic acids are used to synthesize acetic anhydride that servesas an acetylation agent and its major application is for celluloseacetate.