Dehydration reaction of hydroxenin monoacetate in carbon tetrachloride and an aliphatic alcohol under ultrasound irradiation.
A new method for the preparation of an E/Z mixture of vitamin A acetate from hydroxenin monoacetate is described. This two-step reaction was studied by changing the reaction parameters (reaction temperature, ultrasound power, and reaction time) and the alcohol used. This approach consists of the dehydration reaction of hydroxenin monoacetate under ultrasound irradiation in CCl4 and an aliphatic alcohol under an inert atmosphere. The formation of small amounts of HCl from CCl4 and an aliphatic alcohol under ultrasound irradiation is followed by the dehydration reaction of hydroxenin monoacetate. An E/Z mixture of vitamin A acetate was obtained resulting in the desired pentaenes. Some ethers derivatives were also formed as by-products, isolated and characterized. Study of the reaction mechanism is also reported here.
DSM Nutritional Products, Research and Development, P.O. Box 3255, CH 4002 Basel, Switzerland.
Fabrice
F
Aquino
Werner
W
Bonrath
Roberto A
RA
Paz Schmidt
Gerhard
G
Schiefer
D000438:Alcohols / Q000737:chemistry* / Q000528:radiation effects; D002251:Carbon Tetrachloride / Q000737:chemistry* / Q000528:radiation effects; D003890:Desiccation / Q000379:methods*; D004224:Diterpenes; D012176:Retinoids / Q000737:chemistry* / Q000528:radiation effects; D000084562:Retinyl Esters; D013010:Sonication; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000528:radiation effects; D014867:Water / Q000737:chemistry*
D000438:Alcohols; D004224:Diterpenes; D012176:Retinoids; D000084562:Retinyl Esters; C431467:hydroxenin monoacetate; D014867:Water; D014801:Vitamin A; C009166:retinol acetate; D002251:Carbon Tetrachloride