An optically active compound represented by the following formula (I): ##STR1## wherein R.sub.1 denotes a linear or branched alkyl group having 1-18 carbon atoms optionally including one or non-neighboring two or more methylene groups which can be replaced with --X-- or ##STR2## with the proviso that X denotes O or S and Y denotes halogen; R.sub.2 denotes a linear alkyl group having 4-8 carbon atoms: and C* denotes an optically active asymmetric carbon atom. The mesomorphic compound is effective for providing a ferroelectric liquid crystal composition showing improved response characteristics and also effective for suppressing occurrence of reverse domain.
下式(I)所表示的光学活性化合物:##STR1## 其中,R.sub.1 表示具有1-18个碳原子的线性或支链烷基,可选包括一个或非相邻的两个或更多个甲基烷基,该甲基烷基可以被替换为--X--或##STR2##,其中X表示O或S,Y表示卤素;R.sub.2 表示具有4-8个碳原子的线性烷基;C*表示光学活性不对称碳原子。该向列相化合物对于提供表现出改善的响应特性的
铁电液晶组成物是有效的,并且对于抑制反向域的发生也是有效的。