New method for hydroxylating long‐chain unsaturated fatty acids, esters, alcohols, and hydrocarbons

Abstract

SummaryA new method for hydroxylating long‐chain unsaturated compounds is described which involves addition of formic acid at its boiling point to the double bond followed by hydrolysis of the intermediate formate esters. The addition reaction proceeds slowly in the absence of catalysts, but strongly acidic substances, such as perchloric acid, sulfuric acid, and boron fluoride‐acetic acid complex, speed up the addition tremendously.Monohydroxystearic acids can be prepared in good yield by addition of 90–100% formic acid to the double bond of oleic or elaidic acids, methyl oleate, or the unreacted olefinic material separated from the hydrolyzed reaction product of oleic acid with formic acid, followed by hydrolysis. Similarly prepared are dihydroxyoctadecanes from oleyl alcohol, monohydroxyoctadecenoic and dihydroxystearic acids from linoleic acid, monohydroxyhendecanoic acids (isolated as methyl esters) from 10‐hendecenoic (undecylenic) acid, and secondary hexanols from 1‐hexene. Triglycerides are readily formylated if a small amount of mutual cosolvent is employed.Acetic acid in the presence of acidic catalysts also adds to the double bond at its normal boiling point, but yields are lower than with formic acid.