THE SYNTHESIS AND TRANSITION-TEMPERATURES OF SOME FERROELECTRIC HOST MATERIALS BASED ON NS-4-ALKYLCYCLOHEXYLMETHOXY)-2,3-DIFLUOROBIPHENYLS AND NS-4-ALKYLCYCLOHEXYLMETHOXY)-2,3-DIFLUOROBIPHENYLS

A range of 2,3-difluoro-substituted biphenyls incorporating a cyclohex ylmethoxy unit as one terminal chain has been prepared and these mater ials are compared to the analogous compounds already reported with a d imethylene linking group. Related, directly-linked cyclohexylbiphenyls and some open-chain analogues have also been prepared which add to th e diversity of the compounds reported. These were prepared as host mat erials of low birefringence for ferroelectric (S(C)) mixtures and in general, the compounds have quite high S(C) phase stability. Metallati on procedures have been used to prepare arylboronic acids which were e mployed in palladium-catalysed cross-coupling reactions to provide goo d yields of liquid crystal materials. The synthesis and transition tem peratures of these compounds are discussed and compared with each othe r and with other selected ortho-difluoro-substituted systems.