An efficient countercurrent distribution method for the large-scale isolation of dimorphecolic acid methyl ester

Abstract

Effective procedures are reported for isolating and producing dimorphecolic acid (1) and its methyl ester (2) from Dimorphotheca pluvialis seed oil. The methods are suitable even for kilogram-scale production. The acid 1 was prepared by enzymatic hydrolysis of the oil and isolated by crystallization at low temperature. The ester (2) was obtained by methoxide-catalyzed transesterification of the glycerides followed by a countercurrent separation using four vessels and fourteen transfers with the two-phase system 90% aq. methanol-hexane. Methyl 9-oxo-10,12-E,E-octadecadienoate (3) (0.5 to 4%) was observed by GC and GC-MS and characterized by its reduction with sodium borohydride to racemic 2 and by its formation from 2 by Oppenauer oxidation. The complete assignment of the 1H and 13C-NMR signals of 1 and 3 has been carried out using 2D homonuclear and heteronuclear NMR experiments.