NEW MATERIAL:The acetylene compound of formula I (R1 is 6-15C alkyl or 6-l5C alkoxy; R2 is 4-10C alkyl; A and B are group of formula II; n is 0 or 1; X is halogen; * represents asymmetric carbon).

EXAMPLE: 2-(4-Octylphenyl)-1-[4-[(2s)-2-fluorooctyloxy]phenyl]acetylene.

USE: A component of a ferroelectric liquid crystal composition. It is useful for developing large spontaneous polarization of the composition.

PREPARATION: A compound of formula I wherein n is 0 can be produced e.g. by reacting an acetylene derivative of formula II with an iodine compound of formula III in the presence of copper iodide and a palladium catalyst in diethylamine and etherifying the obtained hydroxy compound of formula IV by reacting with a 2-halogenoalkanol toluenesulfonic acid ester of formula V.