Fatty alcohols

Abstract

Abstract“Fatty” or higher alcohols are mostly C11 to C20 monohydric compounds. In probably no other homologous aliphatic series is the current balance between natural and synthetic products so vividly evident. Natural sources, such as plant or animal esters (waxes), can be made to yield straight chain (normal) alcohols with a terminal (primary) hydroxyl, along with varying degrees of unsaturation. In the past, socalled fatty alcohols were prepared commercially by three general processes from fatty acids or methyl esters, occasionally triglycerides. Fatty acids add hydrogen in the carboxyl group to form fatty alcohols when treated with hydrogen under high pressure and suitable metal catalysts. By a similar reaction, fatty alcohols are prepared by the hydrogenation of glycerides or methyl esters. Fatty alcohols are also prepared by the sodium reduction of esters of fatty acids in a lower molecular weight alcohol. The sodium reduction method was ordinarily too expensive; it was displaced early by the other methods; finally most unsaturated alcohols made by this route were largely replaced. Methyl ester reduction continues to provide perhaps 20% of the saturated fatty alcohols, and selective hydrogenation with the use of special catalysts such as copper or cadmium oxides was developed for the production of oleyl alcohol. Synthetic or petroleum technology for long chain alcohols include the Ziegler process, useful for straight chain, even‐numbered saturated products. A second is the carbonylation and reduction of olefins affording medium or highly branched chain alcohols. Paraffin oxidation affords mixed primary alcohols. Fatty alcohols undergo the usual reactions of alcohols. They may be reacted with ethylene oxide to yield a series of polymeric polyoxyethylene alcohols or with acetylene under pressure to yield vinyl ethers or with vinyl acetate to give vinyl ethers.