3hydroxy2butanone

3-hydroxy-2-butanone, also written as 3hydroxy2butanone and commonly known as acetoin, is an organic compound with the formula C4H8O2. It consists of a four-carbon chain bearing a ketone at the second carbon and a hydroxyl group at the third carbon, giving CH3-CO-CH(OH)-CH3. It is a beta-hydroxy ketone and exists as two enantiomers, R- and S-acetoin, due to a stereocenter at C3.

Acetoin is produced by microorganisms during fermentation, particularly lactic acid bacteria. In microbial metabolism, pyruvate is converted to α-acetolactate, which can be decarboxylated to acetoin or further oxidized to diacetyl, a compound with a stronger buttery aroma. Acetoin occurs naturally in trace amounts in some dairy products and fermented foods.

In the flavor and fragrance sector, acetoin contributes a mild, buttery aroma and is used as a flavoring agent. It can serve as a precursor to diacetyl; under certain processing conditions, acetoin is oxidized to diacetyl, influencing the overall buttery flavor profile.

Acetoin is a colorless liquid with a faint, creamy odor. It should be stored in sealed containers away from heat and oxidizing agents, and handled with appropriate protective equipment. It is used in foods and flavors under regulatory guidelines and should be used in accordance with applicable safety and regulatory standards.