Raney nickel dinitriles

In the course of the catalytic hydrogenation of a,us dinitriles over Raney nickel, by-products are obtained from C-N and C-C bond formation. The mechanism of the formation of these compounds was investigated. Cyclic and linear secondary amines can result from the same secondary imine through a transimination process involving a ring-chain tautomerism. Stereochemical results for 2-aminomethyl-cyclopentylamine (AMCPA) are in accordance with a specific cyclisation pathway favored by an intramolecular hydrogen bond giving rise to the cis isomer from aminocapro-nitrile, unfavored in the case of adiponitrile which leads to the trans AMCPA as the major isomer. 

In the hydrogenation of aliphatic dinitriles, cyclization can also be an important reaction pathway.92 Saturation of succinonitrile, 45, (Eqn. 19.45) over Raney nickel gave pyrrolidine, 49, as the primary product even in the presence of ammonia. 24 Intramolecular condensation of the imine-amine intermediate is apparently a very facile reaction, taking place in preference to imine hydrogenation and the intermolecular ammonia-imine condensation. The... 

Numerous studies have shown that low hydrogen overpotential electrically conducting catalysts (e.g., Raney nickel, platinum and palladium on carbon powder, and Devarda copper) can be used to electrocatalyticaUy hydrogenate a variety of organic compounds including benzene and multiring aromatic compounds, phenol, ketones, nitro compounds, dinitriles, and glucose [45, 46, 54, 55, 67-71]. These reactions have been carried out in both batch and semicontinuous flow reactors in most cases, the reaction products were similar to those obtained from a traditional chemical catalytic scheme at elevated temperatures and pressures. 

Hydrogenation of dinitriles into primary diamines over Raney Nickel involves the formation of numerous by products. The nature of dinitrile and hydrogenation intermediates greatly modify the selectivity of the reaction and the catalytic activity The kinetic and thermodynamic aspects of the by products formation are discussed. 

Hydrogenation of aliphatic dinitriles over Raney nickel involves the formation of several unsaturated intermediates described many years ago by VON BRAUN (1) -scheme I-. The reactivities of dinitrile, diamine and above all, of the intermediates are responsible for the formation of numerous byproducts. 

Dinitriles were hydrogenated in a 150 ml autoclave with magnetic stirring under constant pressure and temperature. The Raney nickel was first washed, then weighed with a pycnometer and charged into the reactor with 50 ml of solvent containing ethanol, water and the corresponding diamine. 

Secondary reactions are of prime importance in the hydrogenation of dinitriles over Raney nickel. Though no difference was foreseeable, the ability of each dinitrile or the corresponding hydrogenation intermediates to be cyclized is drastically important in terms of selectivity and catalytic activity of the reaction. Formations of by-products by cydization are under kinetic control for the different reactions observed. 

C13 Hydrogenation of dinitriles Diamines (Raney) nickel Fine chemicals and [42]... 

Hoffer BW, Schoenmakers PHJ, Mooijman PRM, Hamminga GM, Berger RJ, Langeveld ADV, Mouhjn JA. Mass transfer and kinetics of the three-phase hydrogenation of a dinitrile over a Raney-type nickel catalyst. Chem. Eng. ScL 2004 59 259-269. 

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