Catalytic conversion of benzene to phenol

Phenol is very useful intermediate in the manufacture of petrochemicals, drugs, agrochemicals, and plastics. Commercially, phenol is produced by a three-step, high-energy consumption process known as the cumene process. The conversion of a chemical to a value-added product is always economically desirable. More than 90% of phenol consumption in the world is manufactured by the multistep cumene process, in which acetone is coproduced in 1: 1 molar ratio with respect to phenol. However, the drawbacks of the three-step cumene process have spurred the development of more economical routes to decrease energy consumption, avoid the formation of explosive cumene hydroperoxide, and increase the yield. The objective of this article is to highlight benzene-to-phenol conversion technologies with emphasis on direct conversion methods. Gas phase and liquid phase reactions are the two main routes for direct oxidation of benzene to phenol. Indirect methods, such as the cumene process, and direct methods of benzene-to-phenol conversion are discussed in detail. Also discussed is the single-step reaction of benzene to phenol using oxidants such as O₂, N₂O, and H₂O₂. Catalytic conversion of benzene to value-added phenol using a chemically converted graphene-based catalyst, a cost-effective carbon material, is discussed.     

Enhanced methane decomposition over transition metal-based tri-metallic catalysts for the production of COx free hydrogen

In this study, COx-free hydrogen production via methane decomposition was studied over Cu–Zn-promoted tri-metallic Ni–Co–Al catalysts. The catalysts have been prepared by the constant pH co-precipitation method, and the nominal Ni metal loading was fixed at 50 wt % along with other metals at 10 wt% each. The catalyst activity for methane decomposition reaction was examined in a reactor between 400 °C and 700 °C and at atmospheric pressure. Different techniques such as N₂-physisorption, X-ray diffraction, H₂-TPR SEM, TEM, ICP-MS, TGA, and Raman spectroscopy were applied to characterize the catalysts. The relation between the catalyst composition and their catalytic activity has been investigated. The controlled synthesis has resulted in a series of catalysts with a high surface area. Ni–Co–Cu–Zn–Al was the most active and productive catalyst. Various characterizations indicate that the promotional effects of Cu–Zn interaction were the critical factor in catalysts' activity and stability. Ni–Co–Cu–Zn catalyst gave the highest methane conversion of 85% at 700 °C. Zn addition improves the stability of the catalyst by retaining the active metal size during the decomposition reaction. The catalyst was active for 80 h of stability study. The rapid deactivation of the Ni–Co catalyst was due to the sintering of the catalyst at 650 °C. Moreover, carbon species accumulated during the methane decomposition reaction depend on the catalysts' composition. Zn promotes the growth of reasonably long and thin carbon nanotubes, whereas the diameter of carbon nanotubes on unpromoted catalysts was large.     

High-throughput virtual screening and preclinical analysis identifies CB-1, a novel potent dual B-Raf/c-Raf inhibitor,effective against wild and mutant variants of B-Raf expression in colorectal carcinoma

Paradoxical Raf activation via Raf dimerization is a major drawback of wild/mutant B-Raf inhibitors. Herein, we report that CB-1 a novel, potent B-Raf/c-Raf dual inhibitor, effective against colon cancer cells, irrespective of their genetic status. High-throughput virtual screening of the ChemBridge library against wild B-Raf (B-Raf^WT), mutant B-Raf (B-Raf^V600E), and c-Raf was performed using an automated protocol with the AutoDock-VINA. Caco-2 and HT-29 cells were used. Of the 23,365 compounds screened computationally, CB-1 showed the highest binding energy towards B-Raf^WT with a ΔG_binding score of ? 13.0 kcal/mol. The compound was also predicted to be effective against B-Raf^V600E and c-Raf molecules with ΔG_binding energies of ? 10.6 and ? 10.1 kcal/mol, respectively. The compound inhibited B-Raf^WT, B-Raf^V600E and c-Raf kinases with IC₅₀ values of 27.13, 51.70, and 40.23 nM, respectively. The GI₅₀ value of CB-1 was 247.9 nM in B-Raf^WT-expressing Caco-2 cells and 352.4 nM in B-RafV600E-expressing HT-29 cells. Dose-dependent increases in total apoptosis and G₁ cell cycle phase arrest was observed in CB-1-treated colon cancer cells. The compound decreased B-Raf expression in both wild and mutant colon cancer cells. CB-1, a novel, potent dual B-Raf/c-Raf inhibitor was effective against colon cancer cells bearing wild-type and mutant variants of B-Raf expression.