Selective Heterogeneous Catalytic Hydrogenation of Nitriles to Primary Amines

Abstract

Primary amines are important intermediates, especially in the area of pharmaceutical, plastic and agrochemical industry. The heterogeneous catalytic hydrogenation of nitriles is one of the most frequently applied process for the synthesis of diverse amines. However, the control of the selectivity is a critical issue in this reaction. Over the past decade, many studies have been reported using heterogeneous transition metal catalysts for the selective reduction of nitriles to the corresponding primary amines. The type of the catalysts, especially, the chemical nature of metals in the catalysts is one of the most important factors to influence the selectivity, the reaction rate, and possibly also the reaction pathway and the deactivation of the catalyst. Thus, this review focuses on the heterogeneous transition metal catalysts and summarizes the recent developments achieved in the selective catalytic hydrogenation of nitriles to primary amines.

Electrospray ionization mass spectrometric solvate cluster and multiply charged ions: a stochastic dynamic approach to 3D structural analysis

“…Despite, acetonitrile exhibits a significant chemical stability under ESI-MS conditions, showing a rather great competitive binding capability of transition metal ions, thus producing corresponding metal solvate complexes [5,[71][72][73][74][75][76][77][78][79][80][81][82][83][84][85], the catalytic hydrogenation of nitriles is among the most preferred synthetic method yielding to secondary and primary amines [86]. In particular, their catalytic hydrogenation of acetonitrile in presence of transition metal ions is documented [86,87]. The high chemical reactivity of the imine CH 3 CHNH intermediate causes for determination of acetonitrile covalent adducts, mass spectrometrically [88][89][90].…”

Multi-Catalytic Route for the Synthesis of (S)-Tembamide

“…A crucial factor influencing selectivity in the catalytic hydrogenation of nitriles is the nature of the catalyst [48][49][50][51][52][53][54][55][56]. In order to hydrogenate the nitrile in compound (S)-3 with the highest yield towards (S)-tembamide, minimizing the hydrogenolysis of the C-O bond from the benzyloxy group and the formation of secondary and tertiary amines, a transition metal catalyst screening was performed.…”

“…While metal hydrides are generally effective, their use results in the co-production of stoichiometric amounts of metal salts, which may cause elaborate work-up procedures. The alternative catalytic hydrogenation typically yields secondary and tertiary amines as side products, due to the condensation reactions that take place between the reduction intermediate imines (II) with the formed amines (III and VI) as shown in Scheme 2 [46][47][48]. [49] and modified by Greenfield [50].…”

“…For example, the C-O bond of the benzyloxy group is especially susceptible to hydrogenolysis, due to the phenyl ring of the cyanohydrin fragment (see Scheme 3) [37,51,52]. condensation reactions that take place between the reduction intermediate imines (II) with the formed amines (III and VI) as shown in Scheme 2 [46][47][48]. Scheme 2.…”

“…from 95% to 75%) [37]. In contrast, Hertzberg The chemoselectivity of the catalytic hydrogenation of nitriles depends on the substrate structure, the nature and loading of catalyst, the reaction temperature, the hydrogen pressure, the selected solvent and the presence of basic additives such as ammonia [46][47][48]. Furthermore, the hydrogenation conditions may affect the chiral center of the reactant resulting in racemization [53].…”