Synthesis and Some Properties of Nematic Compounds Containing Three Ring Systems

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Abstract
Four series of nematic compounds: 1-(i>truns-4′-n-alkylcyclohexyl)-2-{4”-(trans-4”'-n-alkylcyclohexyl)phenyl}ethanes,trans-4-n-alkylcyclohexylmethyl 4′-(trans-4”-n-alkylcyclohexyl)phenyl ethers and 4-(trans-4′-n-alkylcyclohexyl)methoxyphenyl trans-4”-n-alkylcyclohexane-1”-carboxylates, were prepared and their transition temperatures and transition entropies measured. Their flow-aligned viscosities and birefringences were determined by extrapolation. The N-I transition temperatures and entropies for the 1-(trans-4′-n-propylcyclohexyl)-2-{4”-(trans-4”'-n-alkylcyclohexyl)phenyl}ethanes and 4-{β-(trans-4′-n-propylcyclohexyl)ethyl}phenyl trans-4”'-n-alkylcyclohexane-1”-carboxylates exhibit odd-even effects in relation to the number of carbon atoms in the alkyl chain. The viscosity of 1-(trans-4′-n-propylcyclohexyl)-2-(4”-(truns-4”'-n-pro-pylcyclohexyl)phenyl}ethane is 17.0 c.p. at 20[ddot]C and the viscosity of 4-(β-(trans-4′-n-propylcyclohexyl)ethyl}phenyl trans-4”-n-propylcyclohexane-1”-carboxylate is 34.0 c.p. at 20[ddot]C.