On the other hand, 4-hydroxy-4'-biphenylcarboxylic acid ethyl ester (IV) (38.7 g, 0.160 mol) was dissolved in ethanol (200 ml), and KOH (9 g, 0.160 mol) was added to and dissolved in the solution, followed by adding optically active toluenesulfonic acid 1-methyl-heptyl ester (50 g, 0.176 mol) obtained above, keeping the mixture under reflux for 4 hours, then cooling, adding toluene (200 ml) and 6N--HCl (50 ml), washing the resulting toluene layer with 2N--NaOH aqueous solution and further with water till the washing water became neutral, and distilling off toluene to obtain as a residue, optically active 4'-(1-methyl-heptyloxy)-4-biphenylcarboxylic acid ethyl ester (V) (38.6 g). This product (38.6 g, 0.109 mol) was dissolved in ethanol (6 ml), NaOH (5.3 g, 0.130 mol) and water (26 ml), followed by heating the solution under reflux for 10 minutes to deposit crystals, cooling, adding 6N--HCl (20 ml) to filter off crystals and further recrystallizing from acetic acid to obtain optically active 4'-(1-methyl-heptyloxy)-4-biphenylcarboxylic acid (VI) (23.4 g). This product exhibited liquid crystal phases and the phase transition points were as follows: C-SC* point 160° C., SC*-Ch point 177° C. and Ch-I point 196° C.
