7.3.2 ‘Self’-epoxidation of unsaturated triglycerides
and fatty acid esters
Based on perhydrolysis, a similar method for the epoxidation of unsaturated fatty
acid esters is also feasible, but there is a particular complication. If a triglyceride
containing unsaturated fatty acids reacts with hydrogen peroxide/NovozymÒ 435
(Figure 3), peroxy acids will be formed, which will epoxidize C¼C bonds. The
resulting reaction mixture contains epoxidized triglycerides and some epoxidized
free fatty acids, but unfortunately also some epoxidized mono- and diglycerides,
which are barely separable from the product.
It was found (Ru ̈sch gen. Klaas and Warwel, 1996), that the generation of mono-
and diglycerides is completely suppressed if a small amount of free fatty acids (5
mol%) is added at the beginning of the reaction. Again, perhydrolysis occurs, but the
resulting free hydroxyl groups are immediately re-esterified by the excess of free
7.3 Lipase-mediated lipid oxidations 121
Figure 3. Chemo-enzymatic ‘self’-epoxidation of unsaturated plant oils by NovozymÒ435/H 2 O 2 with-
out addition of free fatty acids.