The synthesis of β-nitropyridine compounds

Abstract

Pyridine and a number of substituted pyridines have been nitrated by reaction with N2O5 followed by reaction with an aqueous solution of SO2xH2O or NaHSO3. The dependence of the yields on the pH of the aqueous reaction medium, on the concentration of SO2xH2O-HSO3-, on addition of methanol to the aqueous phase, and on the reaction temperature were investigated. The yields obtained with NaHSO3 were: 3-nitropyridine 77%, 2-methyl-5-nitro-pyridine 36%, 3-methyl-5-nitropyridinc 24%, 3-acetyl-5-nitropyridine 18%, 5-nitropyridine-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 reaction in liquid SO2), 3-nitropyridine-4-carboxylic acid 48%, methyl 3-nitropyridine-4-carboxylate 75%, 2,3-dimethyl-5-nitropyridine 37%, 2,4-dimethyl-5-nitropyridine 64%, 3-nitroquinoline 10% and 4-nitroisoquinoline 42%.