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Reactions of dienophiles with vegetable oils. I. Reactions of maleic esters with sulfur dioxide catalyst
Author(s) -
Miller W. R.,
Bell E. W.,
Cowan J. C.,
Teeter H. M.
Publication year - 1959
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02639614
Subject(s) - chemistry , organic chemistry , catalysis , yield (engineering) , adduct , maleic anhydride , sulfur dioxide , maleic acid , linoleic acid , copolymer , fatty acid , materials science , metallurgy , polymer
Summary Direct reactions of dibutyl and dimethyl maleate with safflower oil were investigated. When transformed into esters and distilled, the products are generally different from the Diels‐Alder adducts obtained from trans,trans ‐9,11‐linoleic acid. The differences most probably result from the formation of one or more isomers of the known product, of the substituted succinate, of a transannular lactone, or of a mixture of these and other isomers. No definite assignments of structure can yet be made. In one experiment the Diels‐Alder adduct was obtained as the major product from the reaction of dimethyl maleate with safflower oil. Reactions are best carried out by heating safflower oil to 290° while sweeping it with sulfur dioxide. The maleic ester is then added dropwise, and the product is transesterified and distilled. By this procedure a distillable adduct fraction is obtained in yields up to 70%, based on linoleate. Fumaric esters give similar results. Omission of the sulfur dioxide catalyst greatly reduces the yield.