Acetic Anhydride → Retinol, acetate

Participants

Reaction Steps

A 200 ml flask purged with nitrogen was charged with 9.29 g (20 mmols) of 6-chloro-1-hydroxy-3,7-dimethyl-9-(2,6,6-trimethyl-1-cyclohexen-1-yl)-9-phenylsulfonyl-2,7-nonadiene and 40 ml of toluene, followed by agitation for a while, further addition of 5.89 g (100 mmols) of powdery potassium hydroxide (purity of 95%) and 66.3 mg (0.4 mmols) of tetraethylammonium chloride and further agitation at 10° C. for 12 hours. 50 ml of a 5% saline solution was added to the reaction solution for phase separation of the solution. To the resultant organic phase was added 10 ml (105.4 mmols) of acetic anhydride and 0.9 g of sodium carbonate, followed by agitation at 40° C. for 3 hours. After addition of 100 ml of a 10% sodium hydroxide aqueous solution to the reaction solution, the resulting organic phase was separated and washed twice with 100 ml of a 5% saline solution, followed by removal of the solvent by distillation to obtain 12.8 g of a red cily substance. This oily substance was subjected to quantitative determination by high performance liquid chromatography with the result that the yield of vitamin A acetate was 80.9% and the content of the all-trans isomer in the vitamin A acetate was 94.5%. The liquid chromatographic analysis conditions were as follows.

Provenance & Evidence