NEW MATERIAL:A compound of formula I [R and R' are 1-7C straight chain alkyl; the cyclohexane ring is in the trans(equatorial-equatorial configuration)]. USE:An electrooptical display material, capable of increasing the transition temperature between the nematic phase and the isotropic liquid phase remarkably by mixing a small amount thereof with the well-known liquid crystal mixture, having a weakly negative dielectric anisotropy, and usable as a material for dynamic light scattering type display cells in the state of a mixture with another nematic liquid crystal compound having a negative or weakly positive dielectric anisotropy and as a material for electric field type dispaly cells in the state of a mixture with another nematic liquid crystal compound having a strongly positive dielectric anisotropy. PROCESS:A compound of formula II is reacted with a comound of formula III in an inert organic solvent, e.g. benzene or toluene, in the presence of a basic compound, e.g. pyridine, as a catalyst to afford the aimed compound of formula I .
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