C2H4O2

C2H4O2, commonly known as acetic acid or ethanoic acid, is the simplest carboxylic acid with two carbon atoms. Its molecular formula is C2H4O2 and its structural formula is CH3CO2H. It is a weak monoprotic acid with a pKa of about 4.76, making it readily deprotonated in aqueous solution.

At room temperature acetic acid is a colorless, corrosive liquid with a characteristic sharp, vinegar-like odor. It is miscible with water and most organic solvents. The pure liquid, often called glacial acetic acid, has a boiling point around 118 °C and a melting point near 16.6 °C.

Occurrence and production are distinct. Acetic acid occurs naturally in vinegar produced by fermentation and is present in many fruits and other foods in trace amounts. Industrial production is dominated by carbonylation of methanol (the Monsanto/Cativa processes) using rhodium- or iridium-based catalysts, to yield acetic acid; it can also be produced by fermentation under controlled conditions to obtain dilute solutions.

Uses and applications are broad. It is a key reagent in organic synthesis, including the formation of esters such as ethyl acetate and various acetate salts. It serves as a acidity regulator and preservative in the food industry (often labeled as E260) and is used in the production of acetates, solvents, and as a feedstock for other chemical syntheses.

Safety and handling: concentrated acetic acid is corrosive and can cause severe burns upon contact with skin or eyes. Vapors irritate the respiratory tract. It readily reacts with bases to form acetate salts and should be stored in closed, properly labeled containers away from incompatible materials.