NEW MATERIAL:The compound of formula I (R is H or 1W10C alkyl).

EXAMPLE: trans-4-Butyl-trans-4"-(4-cyanophenyl)-trans-octadecahydro-p-terphenyl.

USE: A liquid crystal composition having positive dielectric anisotropy. It has broad and high liquid crystal temperature range for its low viscosity, and has high transparency. The stability to moisture, heat and light is also high.

PROCESS: The compound of formula I can be prepared by (1) reacting the compound of formula II with metallic Mg and then with the compound of formula III, (2) dehydrating the product in the presence of a KHSO4 catalyst, (3) catalytically reducing the resultant compound of formula IV, and demethylating with HBr in acetic acid, (4) catalytically reducing in the presence of a Ru/C catalyst to obtain the compound of formula V, (5) oxidizing the product with chromic anhydride, (6) reacting with benzene magnesium bromide converted to Grignard reagent, (7) dehydrating and catalytically reducing to obtain the compound of formula VI, and (8) iodizing the compound and cyanizing with cuprous cyanide.