N‐bromosuccinimide in the conjugation of fatty acids and oils

Abstract

Summary A series of methyl esters of fatty acids were reacted with N‐bromosuccinimide, and the products were dehydrobrominated by heating. In the reaction of metyyl erucate and methyl oleate with equivalent amounts of N‐bromosuccinimide, bromination occurred in the allylic position farthest from the carboxyl group. Products of dehydrobromination contained 30–40% conjugated dienoic acids. Use of excess N‐bromosuccinimide led to production of both diene and triene conjugation. Products from mono‐acetylenic fatty acids had a double bond conjugated to the triple bond initially present. The product from methyl 9∶12‐linoleate was a complex mixture having diene, triene, and tetraene conjugation. Mustard seed, peanut, olive, karanja, neem, tobacco seed, and safflower oils were reacted with N‐bromosuccinimide. The bromo derivatives could not be satisfactorily dehydrobrominated by heat alone; heating in pyridine, quinoline, or 2∶4∶6‐collidine was more effective. The products from safflower and tobacco seed oils partially gelled during the process. The films of all the treated oils dried in wrinkled patterns.

Oxidations and Dehydrogenations with N-Bromosuccinimide and Related N-Haloimides.

“…Similar action of NBS on friedelin and bromofriedelins also has been reported (115). Conjugation in the methyl esters of fatty acids, e.g., oleic, erucic, and stearolic acids, was introduced by treatment with NBS, then thermal dehydrobromination (156,157). Yields of 30-40% of conjugated dienoic acid esters were obtained.…”

Reactions of the Hydrocarbon Chain of Fatty Acids.

“…evidence which is said to show that monobromination occurs in the allylic position farthest from the carboxyl group (356). The evidence, which is not unequivocal, will be discussed in the section on dehydrohalogenation (see page 133).…”

“…The second instance of apparent selective allylic bromination involved both oleic acid and cfs-6-octadecenoic acid (356). The experimental procedures were similar to those described above for 6-octadecenoic acid, except that no dibasic acids were actually isolated.…”