申请人:Siegfried Aktiengesellschaft
公开号:US04229367A1
公开(公告)日:1980-10-21
Trans-4-alkyl-cyanoarylcyclohexanes are prepared in a stereoselective manner from arylcarboxylic acids of the formula Ar-[Ar].sub.n -Ar-4-COOH, Ar being aryl and n being 0 to 2, by first converting such a carboxylic acid to a mixture of the cis and trans isomers of the corresponding cyclohexa-2,5-diene-4-carboxylic acid, esterifying the resulting isomer mixture with a lower alkanol and further hydrogenating the resulting esters/isomers to produce the cis and trans isomers of the corresponding cyclohexane-4-carboxylic acid esters, isomerizing the cis isomers in the mixture to the trans isomer thereby producing a mixture containing the trans isomer substantially free from cis isomer, stereospecifically saponifying the trans isomer, growing a carbon chain of desired length on the carboxyl group of the resulting carboxylic acid, reducing the carbonyl group thereof, and introducing a cyano group into the terminal aryl group. The resulting product is useful as a nematic liquid crystal.
通过从式为Ar-[Ar].sub.n -Ar-4-COOH的芳基羧酸中首先转化出相应的环己-2,5-二烯-4-羧酸的顺反异构体混合物,然后用较低的醇酯化所得顺反异构体混合物,进一步加氢得到相应的环己烷-4-羧酸酯的顺反异构体,将混合物中的顺式异构体异构为反式异构体,从而产生含有基本无顺式异构体的反式异构体的混合物,立体选择性地皂化反式异构体,使所得羧酸的羧基上生长所需长度的碳链,还原其羰基,并在末端芳基基团中引入氰基,制备出具有向列相液晶性质的Trans-4-烷基-氰基芳基环己烷。