Biocatalysts for the epoxidation and hydroxylation of fatty acids and fatty alcohols

Abstract

Whereas most products of the chemical industry are based on petrochemical feedstocks, considerable efforts have been made during the past few decades to use renewable resources as industrial raw materials. Besides polysaccharides and sugars, plant oils and animal fats play an important role in such programmes because of their ready availability (present production is >100 million t/a, which could be increased on demand) of which the lion’s share is used for nutrition (~85 million t/a), whereas ~ 15 – 20 million t/a are used for the synthesis of polymers, surfactants, emollients, lubricants, bio-diesel, emulsifiers, etc.). From a chemical point of view, most natural triglycerides offer just two reactive sites, the ester group and the double bonds of unsaturated fatty acids. In fact, the chemistry of fats and oils is largely focused on the ester group which can be hydrolyzed or catalytically reduced, leading to glycerol and fatty acids or fatty alcohols, respectively. Reactions involving the alkyl chain or double bonds of triglycerides, fatty acids, fatty alcohols or their derivatives represent far less than 10% of today’s oleochemistry, with the production of sulfonated fatty alcohols and their derivatives being a major process of this kind. Oxidation reactions at the alkyl or alkenyl chains would be highly desirable as they would lead to oleochemicals with new properties, but the methods available today lack selectivity and require harsh conditions. Notable exceptions are the epoxidation of unsaturated plant oils and the synthesis and use of a few hydroxy fatty acids.