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AssigneeBASF SE
InventorsWolfgang Krause, Joachim Paust, Walter Dobler, Hagen Jaedicke
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An improved process for preparing cyclic acetals of 3-formyl-2-butenyltriphenylphosphonium chloride by acetalization of 3-formyl-2-butenyl acetate with an aliphatic 1,3-diol, conversion of the resulting 4-acetoxy acetal into the corresponding 4-hydroxy acetal, Vilsmeier chlorination to give the corresponding 4-chloro acetal and subsequent reaction with triphenylphosphine entails carrying out the first 3 steps in an aliphatic or cycloaliphatic hydrocarbon or mixture of hydrocarbons with 6-8 carbons and the reaction with triphenylphosphine in an alkanol with 1-3 carbons and/or in aliphatic or cycloaliphatic hydrocarbon with 6-8 carbons or a corresponding mixture of hydrocarbons. The process is particularly advantageous when conversion of the 4-acetoxy acetal into the 4-hydroxy acetal is carried out with an aqueous alkali metal hydroxide solution in the presence of phase-transfer catalysts, and the first three, or all four, reaction stages are carried out in the same C.sub.6 -C.sub.8 -hydrocarbon.
An improved process for preparing cyclic acetals of 3-formyl-2-butenyltriphenylphosphonium chloride of the formula I ##STR6## where R.sup.1, R.sup.2 , R.sup.3 and R.sup.4 are each H or CH.sub.3, comprising
An improved process for preparing cyclic acetals of 3-formyl-2-butenyltriphenylphosphonium chloride of the formula I ##STR11## where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each H or CH.sub.3, which comprises reacting the 4-chloro acetals of the formula VI ##STR12## with triphenylphosphine in an alkanol with 1-3 carbons, in an aliphatic or cycloaliphatic hydrocarbon with 6-8 carbons, or in a mixture of an alkanol with 1-3 carbons and an aliphatic or cycloaliphatic hydrocarbon with 6-8 carbons, as solvent.
Dependencies are inferred from the claim text.