Hydrogenation of nitrobenzonitriles using Raney nickel catalyst

Abstract

Abstract-2-, 3-, 4-Nitrobenzonitriles were hydrogenated using Raney nickel catalyst in the environment of two different solvents (methanol and dioxane). The position of the nitro group relative to the nitrile group plays the dominant role in the course of hydrogenation. The nearer the substituent to the nitrile group is, the larger is its effect. 3-and 4-nitrobenzonitriles were hydrogenated to their primary amines, in contrast to 2-nitrobenzonitrile, which was transformed via intramolecular oxidation to 2-aminobenzamide. During hydrogenation, numerous intermediates were formed. The choice of the solvent is another significant parameter affecting the course of hydrogenation.

Harnessing the Selective Catalytic Action of Supported Gold in Hydrogenation Applications

“…122 The latter can also be generated via hydrogenolysis of 4,4 0 -diaminodibenzylamine as a condensation intermediate from p-aminobenzylimine and p-aminobenzylamine. 122,123 The catalytic action of Au/ZrO 2 and Au/Al 2 O 3 in gas phase hydrogenation of p-NBN may be assessed against Pd/Al 2 O 3 and Ni/Al 2 O 3 from the entries in Table 11.4. Reaction over both Au catalysts, with equivalent Au size (7-8 nm), was fully selective to p-ABN.…”

“…A simplified pathway is presented in Figure 11.6 which applies to the published (liquid phase) catalytic studies. 122,123 Partially hydrogenated p-nitrosobenzonitrile and p-(cyanophenyl)-hydroxylamine 124 undergo condensation to 4,4 0 -dicyanoazobenzene. 122 The p-ABN formed can be hydrated to p-aminobenzylamide or hydrogenated to p-aminobenzylimine and p-aminobenzylamine with subsequent hydrogenolysis to p-aminotoluene (p-ATL).…”

“…122,123 Partially hydrogenated p-nitrosobenzonitrile and p-(cyanophenyl)-hydroxylamine 124 undergo condensation to 4,4 0 -dicyanoazobenzene. 122 The p-ABN formed can be hydrated to p-aminobenzylamide or hydrogenated to p-aminobenzylimine and p-aminobenzylamine with subsequent hydrogenolysis to p-aminotoluene (p-ATL). 122 The latter can also be generated via hydrogenolysis of 4,4 0 -diaminodibenzylamine as a condensation intermediate from p-aminobenzylimine and p-aminobenzylamine.…”

“…122 The p-ABN formed can be hydrated to p-aminobenzylamide or hydrogenated to p-aminobenzylimine and p-aminobenzylamine with subsequent hydrogenolysis to p-aminotoluene (p-ATL). 122 The latter can also be generated via hydrogenolysis of 4,4 0 -diaminodibenzylamine as a condensation intermediate from p-aminobenzylimine and p-aminobenzylamine. 122,123 The catalytic action of Au/ZrO 2 and Au/Al 2 O 3 in gas phase hydrogenation of p-NBN may be assessed against Pd/Al 2 O 3 and Ni/Al 2 O 3 from the entries in Table 11.4.…”

“…122 The overall reaction scheme involves disproportionation, reduction, condensation, hydrodeamination and hydrodecarbonation. A simplified pathway is presented in Figure 11.6 which applies to the published (liquid phase) catalytic studies.…”