Wittig Reaction

(redirected from Wittig olefination)
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Wittig Reaction

 

a method of preparing olefins by reacting carbonyl-containing compounds—for example, aldehydes, ketones, formamides, isocyanates, and ketenes— with triphenylphosphine alkylidenes. An example is the formation of isobutene from triphenylphosphine methylene and acetone:

The starting triphenylphosphine methylene is prepared by the action of alkaline reagents on a triphenylmethyl phosphonium salt, which in turn is obtained from triphenylphosphine and an alkyl halide:

The alkaline reagents may be organolithium compounds, sodium amide, alkoxides, and so on.

The Wittig reaction is a very promising process of synthesis, which makes possible the preparation of various olefins, among them polynes (olefins with a large number of multiple bonds).

The synthesis of vitamin A is based on the Wittig reaction, which may also be used to prepare squalene (a precursor of cholesterol), lycopene, bixin esters, and so on.

The Wittig reaction was discovered by the German chemists G. Wittig and U. Schollkopf in 1954.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
The Wittig olefination [1-5], for which Wittig was awarded the Nobel prize in chemistry in 1979, is a powerful method for the formation of carbon-carbon double bonds by the reaction of aldehydes, or ketones, with phosphoranes (Wittig reagents).
One-Pot Combination of the Wittig Olefination with Bromination and Oxidation Reactions,.
Wittig olefination of freshly distilled 8 using ethoxycarbonyl triphenylphosphorane ([Ph.sub.3]P=CHC[O.sub.2]Et) resulted in formation of chiral alkenes 4a and 4b in an approximate 9:1 ratio with the desired Z-isomer, i.e.