64. Acetoin

Nomenclature

CAS number: 513-86-0
3-Hydroxy-2-butanone; 2,3-butanolone; acetyl methyl carbinol; dimethylketol; γ-hydroxy-β-oxobutane.
C4H8O2; mol wt 88.11.
C 54.53%, H 9.15%, O 36.32%.

Description and references

A product of fermentation, also in cream ripened for churning. Obtained by the action of sorbose bacterium or Mycoderma aceti on 2,3-butanediol or by the action of fungi, such as Aspergillus, Penicillium, Mycoderma on sugar cane juice: Browne, J. Am. Chem. Soc. 28, 467 (1906). By action of yeast on diacetyl: Nagelschmidt, Biochem. Z. 186, 317 (1927). From diacetyl by partial reduction with Zn and acid: Diels, Stephan, Ber. 40, 4338 (1907). Fermentation process: Vergnaud, US 2529061 (1950 to Usines de Melle).

Chemical structure

Properties

Liquid. Pleasant odor. mp 15°. d417 0.9972. bp760 148°. nD17.3 1.4190. Miscible with water, alcohol. Sparingly sol in ether, petr ether. Reduces Fehling's soln forming acetic acid. Forms a solid dimer C8H16O4 on standing or on treatment with granulated zinc. The dimer is easily converted back to the monomer by melting, distilling or dissolving.