Diacetyl prepn - by methylvinylketone alkaline oxidn with hydrogen peroxide and epoxybutanone acid rearrangement

摘要

Diacetyl, suitably pure for use as a flavouring agent in the margarine industry and as an additive to baking and pudding powders, is prepd. in high yields by oxidising methylvinyl ketone with H2O2 soln. at 10-60 degrees C in an aq. alkaline medium at pH 7-12 while preventing excess of methylvinyl ketone w.r.t. H2O2, keeping reaction mixt. at given temp. and pH for 0.5-3 hrs., acidifying esp. wit H2SO4, and slowly heating at pH 2 pref. 0.5-1.5 to 70-100 degrees C for 1-6 hrs. to effect rearrangement of 1,2-epoxy-butan-3-one formed. Cpds. destroying peroxides (e.g. CuSO4, FeSO4, MnO2) may be added to acidified reaction soln.