| 摘要 |
NEW MATERIAL:A compound expressed by formula I (R ius 1-10C alkyl; Z is F, Cl or Br; l and m are 0 or positive numbers to give 1 or 2 total of l+m). EXAMPLE:trans-4-Propyl-(3-cyano-4-fluorophenyl)cylohexane. USE:A liquid crystal composition having great positive dielectric anisotropy and good compatibility with another liquid crystal substance. PREPARATION:A 4-substituted acetanilide expressed by formula II is reacted with bromine in acetic acid solvent to give a bromo-substituted derivative expressed by formula III, which is then aminated and diazotized to afford a diazonium tetrafluoroborate. The resultant diazonium tetrafluoroborate is then thermally decomposed to give a fluorobromo-substitution product expressed by formula IV, which is further reacted with cuprous cyanide in a basic solvent, e.g. N,N-dimethylformamide, to afford the aimed compound expressed by formula I (Z is F).
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