Substrate–Solvent Crosstalk—Effects on Reaction Kinetics and Product Selectivity in Olefin Oxidation Catalysis

In this work, we explored how solvents can affect olefin oxidation reactions catalyzed by MCM-bpy-Mo catalysts and whether their control can be made with those players. The results of this study demonstrated that polar and apolar aprotic solvents modulated the reactions in different ways. Experimental data showed that acetonitrile (aprotic polar) could largely hinder the reaction rate, whereas toluene (aprotic apolar) did not. In both cases, product selectivity at isoconversion was not affected. Further insights were obtained by means of neutron diffraction experiments, which confirmed the kinetic data and allowed for the proposal of a model based on substrate–solvent crosstalk by means of hydrogen bonding. In addition, the model was also validated in the ring-opening reaction (overoxidation) of styrene oxide to benzaldehyde, which progressed when toluene was the solvent (reaching 31% styrene oxide conversion) but was strongly hindered when acetonitrile was used instead (reaching only 7% conversion) due to the establishment of H-bonds in the latter. Although this model was confirmed and validated for olefin oxidation reactions, it can be envisaged that it may also be applied to other catalytic reaction systems where reaction control is critical, thereby widening its use.

Substrate-Solvent Crosstalk – Effects on Reaction Kinetics and Product Selectivity in Olefin Oxidation Catalysis

In this work we explored how solvents can affect olefin oxidation reactions catalyzed by MCM-bpy-Mo catalysts and whether their control can be made with those players. The results of this study evidenced that polar and apolar aprotic solvents modulated the reactions in different ways. Experimental data showed that acetonitrile (aprotic polar) could hinder largely the reaction rate whereas toluene (aprotic apolar) did not. In both cases product selectivity at isoconversion was not affected. Further insights were obtained by means of neutron diffraction experiments, which confirmed the kinetic data allowing to propose a model based on substrate-solvent crosstalk by means of hydrogen bonding. In addition, the model was also validated in the ring-opening reaction (overoxidation) of styrene oxide towards benzaldehyde, which progressed when toluene was the solvent (reaching 31% styrene oxide conversion) but was strongly hindered when acetonitrile was used instead (reaching only 7% conversion), due to the establishment of H-bonds in the latter. Although this model was confirmed and validated for olefin oxidation reactions, it can be envisaged that it may also be applied to other catalytic reaction systems where reaction control is critical, while widening its use.

Research Progress on Microreactor Technology in oxidation reactions

: In recent years, the development of the chemical industry has been moving in a green, safe and efficient direction. Oxidation reactions are one of the most important types of reaction, and have key applications in food, medicine, and cosmetics, petrochemicals. However, the occurrence of the oxidation reaction is accompanied by a strong exothermic phenomenon, and improper control can easily lead to safety problems and even explosions. The realization of an environmentally friendly oxidation reaction is a key industrial milestone. The unique structural characteristics of microreactors result in good mass and heat transfer performance, precise control of the reaction temperature, reduced risk of explosion, improved safety production and selectivity of products. These unique advantages of the microreactor determine its significant application value in oxidation reactions. In this paper, the research progress of several typical oxidation reactions including alkane oxidation, alcohol oxidation, aldosterone oxidation, aromatics oxidation and olefin oxidation combined with microreactors is reviewed systematically.

A simple synthesis of [RuCl2(NHC)(p-cymene)] complexes and their use in olefin oxidation catalysis

A simple and efficient synthetic route to [RuCl2(NHC)(p-cymene)] and [Ru(CO3)(NHC)(p-cymene)] complexes making use of a weak base, under aerobic conditions, is reported. This method enables access to a series of...

Hemin-based conjugated effect synthesis of Fe–N/CNT catalysts for enhanced oxygen reduction

Fe/N-codoped carbon nanotubes fabricated through the π–π stacking effect and olefin oxidation polymerization-induced hemin assembly on PPy shows a potential application for ORR.

Application of the CHNS-Analysis for Studying of Polyoxometallates and Ionic Liquids in the Catalytic Systems

The method of CHNS-analysis in combination with ³¹P NMR and UV-VIZ spectroscopy was used to study polyoxometallates and ionic liquids as components of liquid-phase catalytic systems. The composition of imidazolium and TBA salts of tungstоphosphate anions active in the olefin oxidation with H₂O₂ was determined. A method for quantification of [BMIm]Br, Bu₄NBr, Bu₄NHSO₄ in solutions using the CHNS-analysis is proposed. The capabilities of the technique with applying ionic liquids to an inert porous support are evaluated. Using the obtained results, the effect of ionic liquids in combination with a Pt/C catalyst and H₃PMo₁₂O₄₀ heteropolyacid in the oxidation of cyclohexane with О₂-Н₂ gas mixture was determined