LIQUID CRYSTAL COMPOUND WITH NEGATIVE DIELECTRIC ANISOTROPY

摘要

NEW MATERIAL:A compound of formula I (R is 1-8C alkyl, alkoxy; ring A and ring B are formula II and III). EXAMPLE:Trans-4-(trans-4'-propylcyclohexyl)cyclohexanecarboxylic acid 2-cyano- 4-fluorophenyl ester. USE:A liquid crystal composition: it has negative anisotropy and its mixing with other nematic liquid crystals gives a liquid crystal composition which has negative anisotropy and can be used in guest-host type display elements. PREPARATION:The reaction of a carboxylic acid chloride of formula IV with 2-cyano-4-fluorophenol of formula V in the presence of pyridine gives the compound of formula I . The compound of formula V is obtained by dehydration of 5-fluorosalicyl aldehyde oxime with acetic anhydrice.