Kristallin‐flüssige Heterocycloalkane. III. Synthese und kristallin‐flüssiges Verhalten substituierter 1,3‐Dioxadecaline

Publisher Website
Google Scholar
Abstract
Liquid‐Crystalline Heterocycloalkanes. III. Synthesis and Liquid‐Crystalline Properties of Substituted 1,3‐DioxadecalinesLiquid‐crystalline 2‐substituted and 2,6‐disubstituted 1,3‐dioxadecalines (4—6) were synthesized by acid‐catalyzed acetalization of trans‐2‐hydroxymethylcyclohexanol (1) or trans‐4‐alkyl‐trans‐2‐hydroxymethylcyclohexanoles (2) with aldehydes 3 whereby the desired transisomers were formed only. The syntheses of the various aldehydes are also described.Special attention is drawn on the evolution of mesogenic properties of the titlecompounds 4—6 in comparison with known decalines and 1,3‐dioxanes.It was found that the clearing temperatures of the synthesized 1,3‐dioxadecalines are always lower than those of the corresponding decaline derivatives, due to the deformation of the decalineringsystem by the introduction of two oxygen‐atoms. The comparison of 1,3‐dioxanes and 1,3‐dioxadecalines shows that the dioxadecaline ringsystem tends to suppress smectic mesophases in favour of nematics. A first example of a liquid crystalline cis‐fused 1,3‐dioxadecaline (8) is described, too.