METHOD OF VITAMIN A ACETATE SYNTHESIS Russian patent published in 1997 - IPC

FIELD: chemical technology, vitamins. SUBSTANCE: vitamin A acetate is synthesized by halogenation of diol-C₂₀ mono- and diacetates with hydrochloric acid at decreased temperature followed by dihydrohalogenation of synthesized chloroacetates at pH = 5.0-9.0 in the presence of alkaline metal iodide and treatment with reducing agent. After chlorination process an aqueous-acid layer is separated at (-5)-(+2) C and organic layer containing diol-C₂₀ chloroacetates is added to alkali aqueous solution directly that contains alkali metal iodide. Dihydrochlorination process is carried out in the presence of catalytic amount of iodide at mass ratio of diol-C₂₀ and iodide = 1:(0.02-0.04). Potassium or sodium iodide is used as alkaline metal iodide. Yield and content of the end product - 88.1% and 78.2%, respectively. EFFECT: increased yield, improved quality, decreased consumption of reagents. 5 cl, 2 tbl