Studies on diacetyl Part VI

The formation of acetoin from diacetyl

Abstract

When yellow colored fore-shot in the distillation of alcohol mash by continuous still was exposed to sun-light, the color extinguished and increase of acid resulted.
This is due to the formation of acetic acid arising from the decomposition of diacetyl by sun light and the production of acetoin was newly observed.
The change of compoments in foreshot is as follows:-before exposition after 3days after 10days after 30days alcohl 92.6% 95.8 94.2 91.6 methyl alohol 12.5% 12.5 12.5 10.5 aldehyde 0.4594% 0.4025 0.3350 0.1988% acid(as acetic) 0.006 0.288 0.576 0.936 diacetyl 0.5117 0.0465 0 0 acetoin 0 0.2638 0.0749 0.07
If the foreshot which became colorless under exposition to sun-light is taken in the room, yellow color appears again.
The change of diacetyl is more violent in alcohol than in water.
after 10days after 30 days 1%solution of diacetyl in 95% of alcohol diacetyl 0 0 acetion 0.085% 0.009% in water diacetyl 0.075% 0.01% acetoin 0 0
When diacetyl is added to sake-moromimash, both yellow color and special odor of the diketone disappear. It may become butylene-glycol through acetoin.
But no acetoin was found when diacetyl was decomposed with H202.