Premium
A study of the structures and reactions of some methyl substituted unsaturated C 18 ester intermediates in the synthesis of a racemic mixture of 10‐methyloctadecanoic acid
Author(s) -
Lie Marcel S. F.,
Jie Ken,
Leung David W. Y.
Publication year - 1990
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02562419
Subject(s) - chemistry , hydrolysis , organic chemistry , magnesium bromide , methanol , methyl acetate , fatty acid , mineral acid , fatty acid methyl ester , tetrahydrofuran , catalysis , medicinal chemistry , aqueous solution , magnesium , solvent , biodiesel
Methyl 10‐undecenoate was hydrated to methyl 10‐hydroxyundecanoate using mercury (II) acetate in aqueous tetrahydrofuran (THF). Chromic acid oxidation of methyl 10‐hydroxyundecanoate gave methyl 10‐oxoundecanoate, which was hydrolyzed to 10‐oxoundecanoic acid. Reaction of n‐octyl magnesium bromide complex in THF with 10‐oxoundecanoic acid furnished 10‐hydroxy‐10‐methyloctadecanoic acid after hydrolysis. The latter compound was esterified, and dehydration of methyl 10‐hydroxy‐10‐methyloctadecanoate with p ‐toluenesulfonic acid in benzene gave a mixture of unsaturated branched fatty ester intermediates: viz. methyl 10‐methyl‐9‐octadecenoate, 10‐methyl‐10‐octadecenoate and 10‐octyl‐10‐undecenoate. Treatment of the mixture of unsaturated branched fatty ester intermediates with mercury (II) acetate in methanol gave exclusively methyl 10‐methoxy‐10‐methyloctadecanoate. Epoxidation of the same mixture of unsaturated fatty esters with m ‐chloroperbenzoic acid provided a mixture of epoxy derivatives: methyl 9,10‐epoxy‐10‐methyloctadecanoate, 10,11‐epoxy‐10‐methyloctadecanoate and 2‐octyl‐oxirane‐nonanoate. Catalytic hydrogenation of the mixture of unsaturated fatty esters gave a racemic mixture of methyl 10‐methyloctadecanoate, which was hydrolyzed to 10‐methyloctadecanoic acid. The structures of the mixture of unsaturated branched fatty ester intermediates and their derivatives were characterized by chemical and spectroscopic analyses.