Heterogeneous Catalytic Hydrogenation of 3-Phenylpropionitrile over Palladium on Carbon

Krisztina Lévay; Kamilla Dóra Tóth; Tamás Kárpáti; László Hegedűs

doi:10.1021/acsomega.0c00125

Heterogeneous Catalytic Hydrogenation of 3-Phenylpropionitrile over Palladium on Carbon

ACS Omega. 2020 Mar 4;5(10):5487-5497. doi: 10.1021/acsomega.0c00125. eCollection 2020 Mar 17.

Authors

Krisztina Lévay¹, Kamilla Dóra Tóth¹, Tamás Kárpáti¹, László Hegedűs¹

Affiliation

¹ Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, Budafoki út 8, H-1111 Budapest, Hungary.

Abstract

A previously developed and industrially feasible process for selective, Pd-mediated, liquid-phase heterogeneous catalytic hydrogenation of nitriles to primary amines was extended to the reduction of 3-phenylpropionitrile (PPN) to 3-phenylpropylamine (PPA). PPN, which belongs to the homologous series of benzonitrile (BN) and benzyl cyanide (BC), was hydrogenated under mild reaction conditions (30-80 °C, 6 bar), over Pd/C, in two immiscible solvents (dichloromethane/water) and using acidic additives (NaH₂PO₄ and H₂SO₄). Although relatively high conversion (76%) was achieved, the selectivity to PPA (26%) and its isolated yield (20%) were lesser than those in the case of the hydrogenation of BN or BC reported earlier. However, the purity of PPA was >99% without using any purification method. Quantum chemical calculations using a density functional theory (DFT) method were performed to compare the adsorption interactions of the different imine intermediates on palladium, as well as to clarify the differences observed in the primary amine selectivity. PPA is a valuable intermediate for the synthesis of carboxypeptidase B enzyme inhibitors, antimuscarinic drugs, or potential anticancer agents in the pharmaceutical industry.