Propiolonitrile derivatives and liquid crystal compositions comprising

Abstract

A propiolonitrile derivative of formula (I) ##STR1## wherein n1 and n2 each independently stand for 0 or 1; A1, A2 and A3 each independently represent a 1,4-phenylene, a 1,4-phenylene substituted by one or more fluorine atoms, a trans-1,4-cyclohexylene, a 1,3-dioxane-2,5-diyl or a 1,3-pyrimidine-2,5-diyl; Z1, Z2 and Z3 each independently represent a single bond, ethylene, ethenylene, ethynylene, carbonyloxy, oxycarbonyl, methyleneoxy, oxymethylene, 1,4-butylene or 1,4-butenylene; R represents a saturated, aliphatic hydrocarbyl radical of 1-10 carbons, an unsaturated, aliphatic hydrocarbyl radical of 2-10 carbons, a saturated or unsaturated, aliphatic hydrocarbyl radical of 1-10 carbons containing one or more ether linkages (--O--) in the chain and a saturated or unsaturated, fluoro-substituted aliphatic hydrocarbyl radical of 1-10 carbons containing one or more fluorine atoms in the chain; X1 and X2 each independently represent H, F or Cl; provided that at least one of X1 and X2 is F or Cl, when both n1 and n2 are 0, Z1 represents a single bond, ethylene, carbonyloxy or oxycarbonyl and R represents alkyl or alkoxy; or when n1 is 1, n2 is 1 or 0, Z1 and Z2 each independently represent a single bond or ethylene, Z3 represents ethylene and R represents alkyl or alkoxy.