| 摘要 |
NEW MATERIAL:A compound of formula I (R is 1-10C alkyl; ring A is 1,4- trans-cyclohexylene or 1,4-phenylene). EXAMPLE:p-[4-trans-(4'-trans-Propylcyclohexyl)cyclohexyl]phenyl isothiocyanate. USE:Liquid crystal display elements: it keeps the properties of liquid crytals over a wide range of temperatures with positive dielectric anisotropy and a low viscosity. PREPARATION:A compound of formula II is heated together with potassium hydroxide and ethanol under stirring to give a compound of formula III, which is subjected to the known modified Hofmann reaction to give the compound of formula I.
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