Abstract: Compounds which may be used as a dopant or host in a ferroelectric chiral smectic liquid crystal mixture. The compounds are characterized in that they are derivates of an X-hydroxy carboxylic acid and contain the chiral unit (I), in which Ro may be alkyl, alkoxy, halogen, formula (II), where b may be 0 to 3 and the phenyl ring may be substituted, and a is 0 or 1. The chiral unit is combined with a range of mesogenic combinations of groups. Lactic acid derivatives are described in detail (i.e. Ro.dbd.methyl) together with various preparative routes, for example the compound formula (III), which has dopant properties in a range of hosts.

Abstract: Novel lactic acid derivatives which may be used as a component of a ferroelectric smectic liquid crystal mixture, which derivatives have the general formula: ##STR1## in which R.sub.1 is alkyl or alkoxy and R.sub.2 is alkyl. Liquid crystalline compositions containing these compounds are also described.

Abstract: Novel derivatives of cyclic and acyclic terpenoid alcohols, having general formula (I) X--(CO).sub.n --O--T.sub.1, where n=O or l, T.sub.1 is a terpenoid group and X is a combination of cyclic groups, e.g. phenyl, cyclohexyl and pyrimidyl, X preferably contains up to three cyclic groups. Preferred derivatives are esters of cyclic terpenoid alcohols, e.g. menthol, borneol and isopineocampheol, e.g. formula (II) (-)-menthol. Ferroelectric smectic liquid crystal mixtures and devices containing these derivatives as chiral dopants in a tilted smectic host are also described. The properties of various other derivatives of terpenoid alcohols of formula (I) are also described, e.g. those of neomenthol, isolongifolol, fenchol, carveol, myrthenol, nopol, citronellol, perilla alcohol and dihydrocitronellol.