Methanol (500 mL) was cooled to 0°C under ice-salt bath conditions and thionyl chloride (138 g, 4.0 eq.) was added slowly and dropwise. Cis-1,4-cyclohexanedicarboxylic acid (50 g, 1.0 eq.) was added to the above prepared HCl-methanol solution, followed by heating and refluxing the reaction mixture for 1 hour. The reaction process was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the solvent was removed by evaporation and the residue was diluted with distilled water and extracted with ethyl acetate (3 x 100 mL). The combined ethyl acetate layers were washed sequentially with saturated NaHCO3 solution and saturated brine and dried over anhydrous Na2SO4. Finally, the solvent was removed by evaporation to give dimethyl 1,4-cyclohexanedicarboxylate (56.4 g, 97% yield) as a white solid.
