反应详情

Preparation of 6-cyano-2-naphthyl trans-4-n-pentylcyclohexane-1-carboxylate by the following route: ##STR17## trans-4-n-Pentylcyclohexane-1-carboxylic acid chloride is prepared (step A9) by the standard procedure of heating a solution of trans-4-n-pentylcyclohexane-1-carboxylic acid (0.01 mole) in an excess of thionyl chloride for 2 hours. Removal of the excess of thionyl chloride gives a residue of the acid chloride which is mixed with dry pyridine (40 ml) and cooled to 0°-5° C. 6-Cyano-2-naphthol (0.012 mole), as prepared in Example 4 above, is then added and the solution stirred at room temperature for 20 hours; during this time the reaction mixture is protected from atmospheric moisture by a calcium chloride guard tube. The pyridine is then removed by rotary evaporation. The residual solid is purified by column chromatography on silica gel, using chloroform or chloroform:hexane (2:1) mixture as eluent. The purified ester is isolated and crystallised from hexane or methanol until constant transition temperatures are obtained: crystal-nematic liquid crystal (C-N); 86.5° C.; nematic liquid crystal-isotropic liquid (N-I), 168.3° C.

1. customRemoval of the excess of thionyl chloride