| abstract |
The invention relates to a process for the preparation of disubstituted pyrimidines for use as liquid-crystal mixtures, for example in electro-optical devices. The aim is to improve the viscosity and mesophase ranges of liquid crystal mixtures. According to the invention, novel compounds of the formula I are prepared in which the symbols Y are nitrogen and Z is = CH- or Z is nitrogen and Y is = CH-, R is high alkyl and R is high cyano, alkyl, p-alkylphenyl or represent trans-4-alkylcyclohexyl, the term alkyl straight-chain alkyl having 1 to 12 carbon atoms or in one of the radicals R 1 and R 2 highly also a branched alkyl group C deep 2 H deep5-CH (CH deep 3) - (CH deep 2) deep n -, n is an integer from 1 to 3, and the sum of the carbon atoms in the existing alkyl groups is not more than 14. |