| 摘要 |
NEW MATERIAL:An ester compound of formula I (R, R' are C1-8 straight chain alkyl). EXAMPLE:3-Cyano-4-n-heptyloxy-(2'-cyano-4'-n-butylphenyl)benzoate. USE:An additive of a liquid crystal composition having dielectric anisotropy. Addition of a small amount of the compound to a liquid crystal composition increases the absolute value of the dielectric anisotropy; i.e. in the range of low frequency, the anisotropy is positive, and in the range of high frequency, it is negative. Use of the composition to electro-optical display elements lowers the driving voltage of the double-frequency method and of the guest-host method and reduces the electric power consumption. PROCESS:3-Bromo-4-alkoxy benzoic acid chloride of formula II is subjected to the condensation with 2-cyano-4-alkylphenol of formula III in an ether in the presence of pyridine. A compound of formula IV obtained is then made to react with CuCN in N, N-dimethylformamide to give a compound of formula I. |
