Hydrogenation of ortho-substituted nitrobenzenes over palladium catalysts

Hydrogenation of o-nitrobenzenes under mild conditions (1 atm of hydrogen, 20-40 degreesC, organic solvents) over a Pd/C catalyst and the palladium-containing anion exchangers AN-1 and AV-17-8 proceeds without the formation of intermediate products. The yield of primary amines varies from 25 to 100%. It was shown that the palladium-containing anion exchangers are superior to Pd/C in selectivity and stability in the hydrogenation of o-nitrobenzenes. Based on quantum-chemical calculations of substrate molecules, a two-parameter correlation was proposed to describe the electronic and steric effects of the substituent on the hydrogenation rate.