Synthesis and some Physical Properties of trans-4–{β-(trans-4′-n-Alkylcyclohexyl)-1′} -Ethylcyclohexane-1 -Carboxylates

A series of trans-4–(β-(trans-4′-n-alkylcyclohexyl)-1′}-ethylcyclohexane-1-carboxylates, which show nematic phases, was prepared. Their transition temperatures and enthalpies were measured. Their bulk viscosities and birefringences were determined by extrapolation. The influence of terminal halogeno and alkyl groups on the N-I transition temperatures and the C-N transition enthalpies for the trans-4–(β-(trans-4′-n-alkylcy-clohexy1)-1′)-ethylcyclohexane-1-carboxylates is discussed and compared with the influence for the 1–(trans-4′-n-alkylcyclohexyl)-2–(4”-halobiphenyl-4′-yl)ethanes. The bulk viscosity as a function of the third power of the van der Waals radius of the halogeno group and the birefringence as a function of the van der Waals radius of the halogeno group for the 4-halophenyl trans-4′-{β-(trans-4”-n-propylcyclohexyl)-1”}-ethylcyclohexane-1′-carboxylates are discussed.