| 摘要 |
NEW MATERIAL:2,5'-Disubstituted-5,2'-bipyrimidine of formula I (R1 and R2 are 1-10C alkyl or alkoxy; the ring A is group of formula II or formula III). EXAMPLE:2-(p-Pentylphenyl)-5'-propyl-5,2'-bipyrimidine. USE:Useful as a component of a liquid crystal material. It has positive dielectric anisotropy, remarkably large anisotropy of refractive index, broad liquid crystal temperature range, low viscosity, excellent stability to heat, light, temperature, and electricity, and high clear point. It has excellent compatibility with other liquid crystal compounds, and is effective to improve various response characteristics, sharpness and contrast of a liquid crystal derivative when mixed with a biphenyl or ester-type liquid crystal compound. PREPARATION:The compound of formula I can be prepared by (1) reacting the compound of formula IV with hydrogen chloride gas, (2) reacting the resultant compound with ammonia gas, and (3) subjecting the resultant compound of formula V to the condensation cyclization reaction with the compound of formula VIin the presence of a base.
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