Glycerol: An Optimal Hydrogen Source for Microwave-Promoted Cu-Catalyzed Transfer Hydrogenation of Nitrobenzene to Aniline

Copper-Catalyzed Continuous-Flow Transfer Hydrogenation of Nitroarenes to Anilines: A Scalable and Reliable Protocol

A robust supported catalyst that is made up of copper nanoparticles on Celite has been successfully prepared for the selective transfer hydrogenation of aromatic nitrobenzenes to anilines under continuous flow. The method is efficient and environmentally benign thanks to the absence of hydrogen gas and precious metals. Long-term stability studies show that the catalytic system is able to achieve very high nitrobenzene conversion (>99%) when working for up to 145 h. The versatility of the transfer hydrogenation system has been tested using representative examples of nitroarenes, with moderate-to-excellent yields being obtained. The packed bed reactor (PBR) permits the use of a setup that can provide products via simple isolation by SPE without the need for further purification. The recovery and reuse of either EG or the ion-exchange resin leads to consistent waste reduction; therefore, E-factor distribution analysis has highlighted the environmental efficiency of this synthetic protocol.

Recent Studies on the Application of Microwave-Assisted Method for the Preparation of Heterogeneous Catalysts and Catalytic Hydrogenation Processes

Currently, microwave radiation is widely used in various chemical processes in order to intensify them and carry out processes within the framework of "green" chemistry approaches. In the last 10 years, there has been a significant increase in the number of scientific publications on the application of microwaves in catalytic reactions and synthesis of nanomaterials. It is known that heterogeneous catalysts obtained under microwave activation conditions have many advantages, such as improved catalytic characteristics and stability, and the synthesis of nanomaterials is accelerated several times compared to traditional methods used to produce catalysts. The present review article is to summarize the results of modern research on the use of microwave radiation for the synthesis of heterogeneous catalytic nanomaterials and discusses the prospects for research in the field of microwave-induced liquid-phase heterogeneous catalysis in hydrogenation.

Microwave Irradiation as a Powerful Tool for the Preparation of n-Type Benzotriazole Semiconductors with Applications in Organic Field-Effect Transistors

In this work, as an equivocal proof of the potential of microwave irradiation in organic synthesis, a complex pyrazine-decorated benzotriazole derivative that is challenging to prepare under conventional conditions has been obtained upon microwave irradiation, thus efficiently improving the process and yields, dramatically decreasing the reaction times and resulting in an environmentally friendly synthetic procedure. In addition, this useful derivative could be applied in organic electronics, specifically in organic field-effect transistors (OFETs), exhibiting the highest electron mobilities reported to date for benzotriazole discrete molecules, of around 10⁻² cm²V⁻¹s⁻¹.

Impact of Microwaves on Organic Synthesis and Strategies toward Flow Processes and Scaling Up

Microwave-assisted organic synthesis has been widely studied and deliberated, opening up some controversial issues as well. Nowadays, microwave chemistry is a mature technology that has been well demonstrated in many cases with numerous advantages in terms of the reaction rate and yield. The strategies toward scaling up find an ally in continuous-flow reactor technology comparing dielectric and conductive heating.

Microwave-assisted catalysis of water-glycerol solutions for hydrogen production over NiO/zeolite catalyst

In this study, glycerol as an abundant green feedstock was used as a hydrogen source to investigate the reaction of water-glycerol solution decomposition by microwave-assisted catalytic to produce hydrogen over NiO/zeolite catalyst. The catalyst was prepared by inception wetness and then characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy diffraction X-ray (EDX), and transmission electron microscope (TEM) measurements. The conversion process of glycerol into hydrogen was performed in a fixed-bed microwave-assisted reactor. Effect of microwave power, NiO content, and feed flow rate (FFR) on glycerol conversion and hydrogen selectivity were studied. The results of XRD and EDX measurement showed that NiO crystalline exists on the catalyst sample. The particle size of NiO/zeolite was determined in the range of 30–300 nm, and the particle was found well dispersed on the zeolite surface as confirmed by TEM. Furthermore, the maximum conversion rate can achieve about 96.67 %, while the highest hydrogen production was found up to 73.5 % with the condition of 20% of NiO as an active site on natural zeolite. It was found that the NiO content of 20% gave the best glycerol conversion at the microwave power of 600 W and FFR 0.5 ml/min. Microwave-assisted catalytic irradiation of glycerol appears to be a promising candidate for the production of H₂ from an aqueous glycerol solution.