In a 1L four-neck flask, 161.4 g of dimethyl 2-(4-cyano-2-chlorophenyl)-1,3-malonate (1 eq.), 21.7 g of water (2 eq.), and 140.9 g of 95% anhydrous calcium chloride (2 eq.) were added to 606 g of N,N-dimethylacetamide. The reaction was stirred and heated to 140-145°C and kept at this temperature for 20-24 hours. After completion of the reaction, cooled to 30 °C, 352.5 g of water and 303 g of dichloromethane were added. About 70.2 g of concentrated hydrochloric acid was added slowly and the pH of the system was adjusted to 5-7. After partitioning, the aqueous layer was extracted with dichloromethane and the organic phases were combined. The organic phase was concentrated under reduced pressure to give a solution of N,N-dimethylacetamide containing 3-chloro-4-methylbenzonitrile. Vacuum distillation was continued to collect 3-chloro-4-methylbenzonitrile until no product evaporated, resulting in 75.9 g of white solid in 83.0% yield.
