Homogeneous First‐row Transition‐metal‐catalyzed Carbon Dioxide Hydrogenation to Formic Acid/Formate, and Methanol

Abstract

Depletion of fossil fuel for global energy need emits large amount of greenhouse gas carbon dioxide into the biosphere. Carbon dioxide constitutes a sustainable C1 feedstock and cost‐effective raw material for the synthesis of bulk and fine chemicals. The catalytic hydrogenation of CO2 to formic acid, and methanol is an attractive protocol owing to their application in chemical industry and as potential renewable hydrogen storage materials. Catalytic hydrogenation reactions are atom‐economical, green and sustainable synthetic routes towards various new environmentally benign transformations. Homogeneous catalytic hydrogenation reactions based on earth‐abundant, eco‐friendly, first‐row base metals for the preparation of an assortment of organic scaffolds is currently of paramount importance in academia and industry. The surge in base metal catalysis is evident from the increase in reports available in the literature in recent years. In this review, we summarize advances on homogeneous first‐row transition metal catalysed direct and indirect reduction of carbon dioxide to formic acid/formate and methanol based on the hydrogenation strategy.

Hydroxypyridine/Pyridone Interconversions within Ruthenium Complexes and Their Application in the Catalytic Hydrogenation of CO2

“…Furthermore, a relatively sharp resonance corresponding to the hydroxyl group was also present at 11.80 ppm. The corresponding 13 C{ 1 H} NMR spectrum for [2] OTf also suggested that the phosphorus ligand was in the 6-D i PPin form in the [2] + complexes. The signal corresponding to the quaternary carbon containing a hydroxyl group was located at 166.4 ppm as a doublet (J PC = 16.5 Hz).…”

“…The interconversions between the 6-D i PPin and 6-D i PPon* ligand forms offer potential for the activation of small molecules via metal–ligand cooperative mechanisms. It was therefore of interest to explore the catalytic reactivity of these complexes for the hydrogenation of CO 2 . − In accordance with typically utilized reaction conditions, the application of complex 1 or [ 2 ] OTf for the catalytic hydrogenation of CO 2 in the presence of a base was investigated. DBU was chosen as the base to provide [DBU + H]­[OC­(O)­H] as the reaction product (Table ).…”

“…This is an upfield shift with respect to the [2] + complexes. The presence of a carbonyl (C�O) moiety was confirmed by a doublet signal at 169.6 ppm (J PC = 15.3 Hz) in the corresponding 13 C{ 1 H} NMR spectrum. This functional group was also confirmed by the presence of a strong band at 1610 cm −1 for the ν(CO) stretch in the IR spectrum on 3.…”

“…To explore the aforementioned concepts further, we undertook a study focused on exploring the reactivity and catalytic potential of a new derivative of 6-PPon . The synthesis of CO 2 -derived molecules is an area of research that is greatly significant. − One strategy has looked at the hydrogenation of CO 2 to formate salts in the presence of various bases. To the best of our knowledge, the 6-PPon ligand systems have not been explored for their application in the hydrogenation of CO 2 .…”

Ni–N synergy enhanced the synthesis of formic acid via CO2 hydrogenation under mild conditions

“…5 A fascinating TON number was obtained during the hydrogenation of CO 2 to formic acid with various homogeneous catalysts. [7][8][9][10] Despite such exceptional performance, the troublesome separation and recycling of metal complexes, as well as the use of costly and air-sensitive ligands, offer significant barriers in the practical deployment of such molecular complexes. 11 However, the ease of separation, handling, and recyclability of heterogeneous catalysts, which are especially favorable for continuous operation in practice, has inspired substantial research efforts to realize the heterogeneous catalytic synthesis of formic acid through CO 2 hydrogenation.…”