Acetic acid, commonly known as acetic acid (AcOH), is named after the main component of vinegar and is one of the most important fatty acids. It generally exists in many plants in free form or in the form of esters in nature. Molecular formula CH3COOH. The brewing and use of vinegar has a history of thousands of years. There are records of vinegar making in ancient China. However, concentrated acetic acid was successfully developed by Stahl in 1700. Pure acetic acid is a colorless liquid with a pungent taste. Melting point 16.6℃, boiling point 117.9℃, relative density 1.049 (20/4℃). Soluble in water, ethanol, glycerol, ether and carbon tetrachloride; insoluble in carbon disulfide. Anhydrous acetic acid solidifies into ice at low temperature, commonly known as glacial acetic acid. It is corrosive. It is a weak organic acid with the general properties of acid and can undergo esterification reaction with alcohol.