An optically active compound having a .delta.-valerolactone ring which is a ferroelectric liquid crystal and is represented by the following general formula (I): ##STR1## wherein m is an integer of from 1 to 8, Z is a group represented by the following formula: ##STR2## in which each of l and k is a number of 1 or 2 and l and k satisfy the requirement of 2.ltoreq.(l+k).ltoreq.3, X stands for a direct bond, ##STR3## Y stands for ##STR4## and A.sub.1 and A.sub.2 independently stand for --H, --F or --Cl, ##STR5## R stands for ##STR6## in which n is an integer of from 1 to 18, and * indicates the asymmetric carbon atom.
一种具有.delta.-
戊内酯环的光学活性化合物,是一种
铁电液晶,由以下通式(I)表示:##STR1## 其中m为1到8的整数,Z为以下式子表示的基团:##STR2## 其中l和k分别为1或2的数字,且l和k满足2≤(l+k)≤3的要求,X代表直接键,##STR3## Y代表##STR4##,A.sub.1和A.sub.2分别代表--H,--F或--Cl,##STR5## R代表##STR6##,其中n为1到18的整数,*表示不对称碳原子。