1,2,3,4,5,6-HEXA(EQ)ALKYLCYCLOHEXANE MODEL COMPOUNDS FOR STRUCTURE-PROPERTY COMPARISONS OF SATURATED DISCOTIC LIQUID-CRYSTALS

The new hydrocarbon (1-alpha,2-beta,3-alpha,4-beta,5-alpha,6-beta)-hexahexylcyclohexane (19) and a number of new and differently functionalized scyllo-hexaalkylcyclohexane derivatives (16a,b, 18a-c) with identical stereochemistry were synthesized stereospecifically starting from simple chemical materials. In comparison to the known scyllitol hexaester 1 and the hexaether 2 none of the novel compounds 16, 18, and 19 were thermomesomorphic. This extreme difference in the thermotropic liquid-crystalline behaviour of the hexa(eq)hydroxycyclohexane (scyllitol) derivatives 1 and 2 on the one hand and of our varied hexa(eq)-alkylcyclohexans 16, 18, and 19 on the other obviously is a function of the presence and the position of the element oxygen within the side chains of these symmetric star-/disc-shaped compounds. Details concerning this oxygen effect are discussed briefly.