This embodiment includes the following steps: Step 1. Add 14.3g (0.1mol) o-chlorobenzyl alcohol, 3.7g copper-manganese composite catalyst and 1.6g (0.01mol) 2,2,6,6-tetramethylpiperidine oxide into the reaction kettle, Then add an alcohol-water mixed solution made by mixing 33 mL of ethanol and 66 mL of deionized water, Pour ammonia gas into the reactor until the ammonia gas pressure in the reactor is 0.2MPa, and then close the ammonia gas inlet valve. Continue to feed oxygen into the reaction kettle to a pressure of 0.4MPa, and then continue to supply oxygen at this pressure; The copper-manganese composite catalyst consists of 1.7 g (0.01 mol) copper chloride dihydrate and 2.0 g (0.01 mol) manganese chloride tetrahydrate; Turn on the magnetic stirring device in the reaction kettle, and at the same time heat it to the temperature of the system in the reaction kettle at 40??C to perform ammonia oxidation reaction for 4 hours After the reaction is over, the pressure of the reactor is relieved, the product system after the ammoxidation reaction is cooled to 5??C, and 14.0 g of off-white needle-like solids are obtained by suction filtration, namely crude o-chlorobenzonitrile; Step 2: Using 28 mL of alcohol-water mixed solution to recrystallize 14.0 g of the crude o-chlorobenzonitrile obtained in step 1, to obtain white needle-like crystals, namely o-chlorobenzonitrile; The alcohol-water mixed solution is formed by mixing ethanol and deionized water in a volume ratio of 1:2. The o-chlorobenzonitrile prepared in this example was dried and weighed 13.3g; after calculation, The yield of the o-chlorobenzonitrile prepared in this example was 97.1%, and the mass purity of the o-chlorobenzonitrile prepared in the example was 97.5% as determined by gas chromatography.
