The general procedure for the synthesis of 1,2-cyclopentanedicarboxylic acid and formamide (CAS: 77287-34-4) as raw materials for the synthesis of 1,2-cyclopentanedicarboxylic acid is as follows: 50 g of 1,2-cyclopentanedicarboxylic acid and 15 g of formamide were mixed, and the reaction was carried out by raising the temperature up to 170 °C under the protection of nitrogen while evaporating the low-boiling by-products. The reaction progress was monitored by HPLC and terminated when the residual amount of raw material was less than 0.2%. After the reaction solution was cooled to 80 °C, 50 g of deionized water and 0.5 g of activated carbon were added and stirred at 50 °C for 30 min. The reaction mixture was thermally filtered and the filtrate was cooled to 20 °C and extracted with dichloromethane. The organic phase was concentrated to no fraction and dried at 90 °C. Subsequently 100 g of toluene was added, the mixture was cooled to 5 °C and dried under reduced pressure at 40 °C to give about 60.6 g of white crystal product. The yield of this step was 93.5% and the product was ≥99% pure and ≥98% content.
