1. Synthesis of 2,3-dichlorobenzoyl cyanide
2,3-Dichlorobenzoyl chloride (20.0 g, 100 mmol) and cuprous iodide (I) (0.90 g, 4.7 mmol) were suspended in acetonitrile (50 mL) and stirred at room temperature until a yellow homogeneous solution was formed. Solid sodium cyanide (5.15 g, 110 mmol) was added slowly with a controlled addition time of 5-8 hours. After addition, stirring of the reaction mixture was continued for 1 h. The reaction progress was monitored by HPLC. The resulting inorganic salt (mainly NaCl) was removed by filtration and the filter cake was washed with acetonitrile (15 mL). Acetonitrile was removed by distillation under reduced pressure (~150 mbar). Sodium metabisulfite (Na2S2O3, 0-4 g, 3 mmol) was added to remove trace iodine. Finally, the product was purified by vacuum distillation (jacket temperature 140°C, boiling point 115°C/2 mbar) to give 2,3-dichlorobenzoyl cyanide in >80% yield and 100% purity (as determined by analytical HPLC) with a melting point of 60°C.
