Controlling the All-trans Stereochemistry in Liquid Crystalline 4,4′-Dialkyl-[1,1′-bicyclohexyl] Compounds

Abstract

A good part of today’s liquid crystals (LCs) for display applications are derived from the Darzens–Nenitzescu reaction which, in a one-pot-process, yields 1,4-trans-acylphenylcyclohexanes from acid chlorides, benzene, and cyclohexene. A mechanism for this process is proposed based on quantum-chemical computations. The products of this reaction can be further elaborated to all-trans-4,4′-disubstituted-[1,1′-bicyclohexane] compounds, essential components in almost all fast switching LC-mixtures. An equilibration process involving carbo­cations is used to control the diastereomer distribution.