Synthese und flüssigkristalline Eigenschaften 2,6-disubstituierter Naphthaline

Synthesis and Liquid-Crystal Properties of 2,6-Disubstituted Naphthalene Derivatives The syntheses and the mesomorphic properties of a series of novel 2,6-disubstituted naphthalenes are described. 4-6-(n-Alkyl)-2-naphthyl]benzonitriles 5 and 4-6-(n-Alkoxy)-2-naphthyl]benzonitriles 8 exhibit widerange nematic mesophases. 6,6′-Di(n-alkyl)-2,2′-binaphthyls 6 have been isolated as by-products from the reaction mixtures of 5 . Some of these novel compounds have polymorphic properties. The esters 13 and 15 of 4-(6-hydroxy-2-naphthyl)benzonitrile show enhanced mesophase stabilities which reach maximum values in the series of α, β-unsaturated esters 15 . The 4-(n-pentyl)benzoate 14 of the same (hydroxynaphthyl)benzonitrile has a melting point of 125° and a clearing point of > 310°. This particular derivative belongs to those liquid-crystalline compounds having the broadest purely nematic-phase range. In addition, (RS)-4-(2-pentyl-6-chromanyl)benzonitrile ( 20 ) and three compounds with two and four laterally arranged CN groups at the bicyclo2.2.2]octene, bicyclo2.2.2]octadiene, and the phenyl-ring systems 31 – 33 were synthesized. Only 20 shows mesomorphic properties.