General procedure for the synthesis of 3-methyl-4-nitrobenzonitrile from 3-methyl-4-nitrobenzamide: 3-methyl-4-nitrobenzamide (5 g, 28 mmol) was dissolved in 300 ml of toluene under stirring conditions, followed by the slow addition of phosphorus oxychloride (POCl3, 22 g, 140 mmol). After the addition was completed, the reaction mixture was heated to reflux for 24 hours. Upon completion of the reaction, the mixture was carefully poured into ice water and extracted three times with ethyl acetate. The organic phases were combined, dried with anhydrous sodium sulfate, filtered and concentrated under reduced pressure. Finally, the residue was purified by ethanol recrystallization to afford the target product 3-methyl-4-nitrobenzonitrile (3.2 g, 70% yield).
