Carbon-Supported Cobalt Nanoparticles as Catalysts for the Selective Hydrogenation of Nitroarenes to Arylamines and Pharmaceuticals

Abstract

Chemoselective hydrogenation of nitroarenes under industrially viable conditions is one of the attractive reaction for chemical, pharma, and pesticide industries. Herein, we report a reusable, stable, and renewable carbon-supported cobalt nanocatalyst (Co/MA-800) for the chemoselective reduction of structurally diverse nitroarenes with molecular hydrogen. The Co/MA-800 nanocatalyst was prepared via simple and straightforward carbonization of macroalgae and characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, H 2 -temperature programmed reduction, N 2 adsorption−desorption, and Raman spectroscopy. The cobalt content in Co/MA-800 is determined by inductively coupled plasma-atomic emission spectroscopy analysis. Furthermore, we show the hydrogenation of four marketed nitro pharmaceuticals that were selectively transformed to the respective primary anilines in excellent yields. We also demonstrate the synthesis of two industrially relevant key pharma intermediates on the ∼1 g scale, which are further employed in the preparation of drug compounds such as Linezolid and Tizanidine. The Co/MA-800 nanocatalyst was also active for the reductive amination of bezaldehyde and nitroarenes to achieve imines in good yields. In addition, the Co/MA-800 nanocatalyst is recycled 5 times without significant drop in catalytic activity.

Nitrogen-Doped Carbon Supported Co/Ni Bimetallic Catalyst for Selectively Reductive N-Formylation of Nitroso in Guanine Synthesis

“…S1A, all XRD patterns show a diffraction peak at 2θ = 26° which is assigned to graphitic carbon [18]. For the monometallic catalysts 2wt%Co@NC-700 and 2wt%Ni@NC-700, two additional weak diffraction peaks at 2θ = 44.5°, 51.8° are observed in the XRD patterns, which are ascribed to the planes (111), ( 200) and (220) of Co 0 and Ni 0 [10,16]. The peaks of Co 0 /Ni 0 phases at 2θ = 44.5°, 51.8° are also found in the patterns of all bimetallic catalyst samples.…”

“…Recently, catalysts based on non-noble metals, such as Fe [9], Co [10], and Ni [11], have demonstrated high efficiencies in the hydrogenation or reduction of nitroarenes. Meanwhile, the investigations revealed that nitrogendoped carbon materials (NCMs) were excellent supports for enhancing the activity of metal catalysts [12][13][14][15][16][17][18].…”

Simple RuCl3‐catalyzed N‐Methylation of Amines and Transfer Hydrogenation of Nitroarenes using Methanol

“…Next, the reduction of nitroarenes is one of the most widely used reaction in chemical industries; the resulting anilines are often found in fragrances, dyestuff, and pharmaceuticals [31b,34] . During one‐shot N ‐methylation of nitroarenes with methanol, the formation of low amounts of anilines was noticed.…”

A new nanomagnetic Pd-Co bimetallic alloy as catalyst in the Mizoroki–Heck and Buchwald–Hartwig amination reactions in aqueous media

“…Arylamines and their derivatives possess a paramount importance as intermediates for pharmaceuticals and natural products, agrochemicals, conducting polymers (PANI), and dyes in the chemical industry 57 – 59 . Arylamines are extremely important ligand for the coordination to transition metals 60 .…”