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Synthesis of long chain a,B ‐alkynoic and a,B ‐alkynoic acids via B ‐keto esters
Author(s) -
Silveira A.,
Weslowski T. J.,
Weil T. A.,
Kumar V.,
Gillespie J. P.
Publication year - 1971
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/bf02638513
Subject(s) - chemistry , aqueous solution , alkyl , halogenation , product (mathematics) , proton magnetic resonance , organic chemistry , physics , nuclear magnetic resonance , mathematics , geometry
A general method for the synthesis of long chain α,β‐alkynoic acids from β‐keto esters is described. The synthesis involves conversion of the β‐keto ester to the corresponding pyrazolone, then halogenation and treatment of the resultant 4,4‐dihalo product with dilute aqueous alkali to form the α,β‐alkynoic acids. Specifically, 2‐octynoic, 2‐nonynoic and 2‐decadecynoic acids were prepared as representative examples. If the β‐keto ester has an alkyl group at the α‐position, the final product is a mixture of cis and trans α‐substituted‐α,β‐unsaturated alkenoic acids, which may be separated by gas‐liquid chromatography. Pertinent IR and proton magnetic resonance data are used in characterizing the stereochemistry of products and a possible mechanism for the product forming reactions is presented.