To avoid problems such as predissolution of reactants and produce the subject high-quality compound having various structures in good yield using a nontoxic solvent by carrying out the Wittig reaction according to a specific method.
The Wittig reaction is carried out in a manner without dissolving all the reactants and any of the produced carotenoids in a polar reactional medium. A nontoxic solvent which remains in a single phase even by adding water up to 30 vol.% and is capable of manifesting good solubility even for a triarylphosphine oxide formed as a by-product is preferred as the polar reactional medium. Among them, a lower alkanol is preferred. Typically, 0.5-2 wt.% of the reactants or carotenoids is soluble in the polar reactional medium. The method is suitable for the production of licopene using [3,7,11-trimethyl- dodecyl-2,4,6,10-tetraenyl]-triphenylphosphonium chloride, etc., as a starting substance.
RUDIN PETER (CH)
KREIENBUEHL PAUL (CH)
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