METATHESIS OF UNSATURATED FATTY-ACID ESTERS - A SIMPLE APPROACH TO LONG-CHAINED DICARBOXYLIC-ACIDS

Long-chained, symmetric unsaturated C18-, C20- und C26-dicarboxylic acid esters are easily accessible from natural fatty acid esters by metathesis in a two-step procedure. In the first step unsaturated fatty acid esters are cleaved by metathesis with ethylene. Pure oleic acid ester or fatty acid methylesters, produced from high-oleic sunflower oil or from rapeseed oil by transesterification with methanol, are converted to 1-decene and 9-decenoic acid methylester. From erucic acid methylester 1-decene and 13-tetradecenoic acid methylester are achieved, Using our newly developed high efficient catalytic system B2O3-Re2O7/Al2O3-SiO2 + SnBu4 conversion rates of 86 - 96 % are obtained and the terminally unsaturated fatty acid esters are isolated in yields of 61 - 83%. In the second step 9-decenoic and 13-tetradecenoic acid methylester as well as 10-undecenoic methylester, which is commercially obtained by pyrolysis of ricinoleic acid ester, are converted to 9-octadecenedioic-, 13-hexacosenedioic- and 10-eicosenedioic acid dimethylester, by which process ethylene is eliminated. The conversion rates are 89 - 99% and the dicarboxylic acid dimethylesters are isolated in yields of 77 - 84%.