The synthesis of beta-nitropyridine compounds

Pyridine and a number of substituted pyridines have been nitrated by reacti on with N2O5 followed by reaction with an aqueous solution of SO(2)xH(2)O o r NaHSO3. The dependence of the yields on the pH of the aqueous reaction me dium, on the concentration of SO(2)xH(2)O-HSO3-, on addition of methanal to the aqueous phase, and on the reaction temperature were investigated. The yields obtained with NaHSO3 were: 3-nitropyridine 77%, 2-methyl-5-nitropyri dine 36%, 3-methyl-5-nitropyridine 24%, 3-acetyl-5-nitropyridine 18%, 5-nit ropyridine-3-carboxylic acid 15%, 3-chloro-5-nitropyridine 11%, 4-methyl-3- nitropyridine 39%, 4-acetyl-3-nitropyridine 67%, 4-cyano-3-nitropyridine 45 %, 4-phenyl-3-nitropyridine 68%, 4-formyl-3-nitropyridine 62% (from reactio n in liquid SO2), 3-nitropyridine-4-carboxylic acid 48%, methyl 3-nitropyri dine-4-carboxylate 75%, 2,3-dimethyl-5-nitropyridine 37%, 2,4-dimethyl-5-ni tropyridine 64%, 3-nitroquinoline 10% and 4-nitroisoquinoline 42%.