General procedure for the synthesis of cis-cyclohexane-1,2-dicarboximide from 3-hydroxy-1H-isoindol-1-one: 30 g (0.20 mol) of phthalimide was added to a 1L stainless steel magnetically stirred autoclave. After adding 700 ml of methanol, 1.5 g of lanthanum chloride and a composite catalyst of copper powder loaded alumina, the reaction vessel was sealed. Use nitrogen to replace the air in the autoclave and start stirring. The temperature was raised to 250 °C, at which time the gauge pressure was 13.2 MPa. Subsequently, hydrogen was introduced into the system and the pressure was increased to 15 MPa. The reaction was maintained at this temperature and pressure for 30 h. The reaction was completed by shutting down the hydrogen inlet. Upon completion of the reaction, the hydrogen inlet valve was closed and cooled to 10°C. The kettle was again replaced with nitrogen. The gas in the kettle was again replaced with nitrogen and the reaction solution was poured out. The catalyst was removed by filtration and the filtrate was transferred to a rotary evaporator. Distillation was stopped after removing 600 ml of methanol by distillation at atmospheric pressure. Cooled to room temperature, a large number of white granular crystals were precipitated and filtered through a Brinell funnel. The filtrate and distillate were combined and the filter cake was washed with 50 ml of water. After drying, 28.8 g of pure white crystalline powder was obtained, and its melting point ranged from 138.8 °C to 140.3 °C. The product was analyzed by liquid chromatography. The purity of the product was 98.87% by liquid chromatography. The reaction selectivity was 93.05% and the yield was 94.11% in terms of phthalimide.
