NEW MATERIAL:A pyrimidine compound I (R1 and R2 are 1W12C alkyl, substituted hydrocarbon group or substituted or unsubstituted alkyloxy containing O instead of one CH2 or two CH2 not bonded eath other in alky group; the ring A and the ring B are group shown by the formula VI or formula VII).

EXAMPLE: 2-[4-{β-(trans-4-Pentylcyclohexyl)ethyl} phenyl]-5-propylpyrimidine.

USE: A liquid crystal substance capable of constituting a liquid crystal composition suitable for various kinds of liquid crystal display elements, having a wide liquid crystal teperature range, having dielectric anisotropy at low viscosity, having improved stability to water, heat, light, air, etc., and improved compatibility with other liquid crystal compounds.

PREPARATION: A compound shown by the formula II is reacted with a hydrogen chloride gas in the presence of an alcohol to give a compound shown by the formula III and this compound is reacted with an ammonia gas in an alcohol to give a compound shown by the formula IV. Then this compound is condensed and subjected to ring formation with a compound shown by the formula V in the presence of a proper base catalyst to give a compound shown by the formula I.