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A hydrogen-bonding and acid cooperative catalysis strategy for the benzylation of arenes with benzyl alcohols over acidic ILs [SO3H-PMIm][OTf] was reported.

Herein, we report a CO2-mediated base catalysis approach for the activation of triple bonds in ionic liquids (ILs) with anions that can chemically capture CO2 (e.g., azolate, phenolate, and acetate), which can achieve hydration of triple bonds to carbonyl chemicals. It is discovered that the anion-complexed CO2 could abstract one proton from proton resources (e.g., IL cation) and transfer it to the CN or CC bonds via a six-membered ring transition state, thus realizing their hydration. In particular, tetrabutylphosphonium 2-hydroxypyridine shows high efficiency for hydration of nitriles and CC bond-containing compounds under a CO2 atmosphere, affording a series of carbonyl compounds in excellent yields. This catalytic protocol is simple, green, and highly efficient and opens a new way to access carbonyl compounds via triple bond hydration under mild and metal-free conditions.

N-Methylation of amines with CO2/H2 to N-methylamines over non-noble metal catalysts is very interesting but remains challenging. Herein, we present an alcohol (e.g., ethanol) promoted strategy for the N-methylation of anilines with CO2/H2 with high efficiency under mild conditions (e.g., 125 °C), which is achieved over a cobalt catalytic system composed of Co(OAc)2·4H2O, triphos and Sn(OTf)2. This catalytic system has a broad substrate scope and is tolerant toward a wide range of anilines and N-methyl anilines, and a series of N,N-dimethyl anilines were obtained in high yields. Mechanism investigation indicates that the alcohol solvent shifts the equilibrium of CO2 hydrogenation by forming an alkyl formate, which further reacts with the amine to produce N-formamide, and Sn(OTf)2 promotes the deoxygenative hydrogenation of N-formamides to afford N-methylamines. This is the first example of the N-methylation of amines with CO2/H2 over a cobalt catalytic system, which shows comparable performance to the reported Ru catalysts and may have promising applications.

N-heterocyclic compounds are important chemicals, and their reductive synthesis using H2 under mild conditions is attractive but challenging. Herein, we report chemoselective hydrogenation of 2-nitroacylbenzenes to 2,1-benzisoxazoles under ambient conditions for the first time, wihch is achieved over cellulose-derived carbon (c-C) supported Pt nanocatalyst (Pt/c-C), and a series of 2,1-benzisoxazoles can be obtained in excellent yields. Pt/c-C also shows high performance for ambient reductive amination of levulinic acid with H2, accessing various pyrrolidones in excellent yields. The systematic studies indicated that the c-C support played multiple roles in catalysis with enhancing electron density of the Pt nanoparticles and activating reactant molecules. Especially, the O-containing groups on the c-C surface provided the c-C support with both acid and base features, thus endowing Pt/c-C with high performances. This work provides an accessible and highly efficient catalyst for reductive synthesis of N-heterocycles using H2 under ambient conditions, which may have promising applications.

The fabrication of catalysts that can activate CO2 under ambient conditions is very interesting but challenging. Metal–organic hybrids (MOHs) have promising applications in catalysis, and their fabrication from renewable resources is very attractive. Herein, we report a simple protocol to fabricate metal–organic hybrids (MOHs) from chitosan, phytic acid and ZnCl2, obtaining mesoporous MOH-Zn possessing –OH, –NH2, and –PO4 groups. The resulting MOH-Zn shows excellent activity for CO2 activation and enables the cyclization of epoxides with CO2 to proceed under ambient conditions, affording a high turnover frequency of 7.8 h−1. The high performance of MOH-Zn originates from the synergistic effects among multi-functional sites in the catalysts.

A metal-free and highly efficient catalytic system involving a task-specific ionic liquid, [P4444][p-2-O], and a pyrene-based conjugated polymer was developed for direct CO2 capture from air and its further photoreduction to CO under visible light irradiation, affording a CO production rate of 47.37 μmol g−1 h−1 with a selectivity of 98.3%.

B(C6F5)3 was proven to be an efficient metal-free catalyst for the methylation of amines using CO2 as a C1 building block in the presence of hydrosilanes under easy-handling conditions. A broad range of N-alkylanilines, dialkylamines and primary anilines all proceeded well under the catalytic conditions.

The selective oxidation of glycerol was investigated using AuPd/TiO2 as the catalyst in the presence of AlCl3, and lactic acid was obtained as the predominant product. It was demonstrated that AuPd/TiO2 and AlCl3 played synergistic roles in the production of lactic acid. The possible reaction pathway was proposed, in which glycerol was first oxidized to glyceraldehyde and dihydroxyacetone, catalysed by AuPd/TiO2, followed by the formation of lactic acid, catalyzed by AlCl3.

In this work, we developed a facile and efficient route to deposit ultrafine Pt particles onto multi-walled carbon nanotubes (MWNTs) with the aid of tip sonication. The loading of Pt on the MWNTs could attain the very high level of 50 wt% and the size of the Pt particles could be controllably tuned in the range 1.9–3.5 nm with narrow size distributions. The resultant nanocomposites were applied to catalyze the hydrogenation of nitrobenzene under solvent-free conditions. It was demonstrated that the Pt/MWNT catalysts showed excellent activity with a high turnover frequency (e.g., 69 900 h−1) as well as superior selectivity to aniline (e.g., >99%) in this reaction.