Theoretical Study on the Dehydrogenation Reaction of H_2S by VS^+ (~3Σ^-)

The dehydrogenation reaction of H2S by the ^3Σ^- ground state of VS^＋： VS^＋ ＋ H2S → VS2^＋ ＋ H2 has been studied by using Density Functional Theory （DPT） at the B3LYP/DZVP level. It is found that the reaction proceeds along two possible pathways （A and B） yielding two isomer dehydrogenation products VS2^＋-1 （^3B2） and VS2^＋-2 （^3A1）, respectively. For both pathways, the reaction has a two-step-reaction mechanism that involves the migration of two hydrogen atoms from S2 to V^＋, respectively. The migration of the second hydrogen via TS3 and that of the first via TS4 are the rate-determining steps for pathways A and B, respectively. The activation energy is 17.4 kcal/mol for pathway A and 22.8 kcal/mol for pathway B relative to the reactants. The calculated reaction heat of 9.9 kcal/mol indicates the endothermicity of pathway A and that of -11.9 kcal/mol suggests the exothermicity of pathway B.

A NOVEL DEHYDROGENATION REACTION UNDER SINGLET OXYGENATION CONDITION

1-Aryl-2-merhy1-4,5-dihydropyrro1-3-carboxylic acid ethyl ester was observed to dehydrogenate to give 1-ary1-2-methyl-pyrro1-3-carboxylic acid ethyl ester upon irradiation in the presence of oxygen and in the presence or absence of ms-tetraphenylporphine.

MCSCF STUDIES ON THE IRC AND REACTION RATE CONSTANTS FOR THE DEHYDROGENATION REACTION OF VINYL RADICAL

The transition state(TS) and Intrinsic Reaction Coordinate (IRC) for the titled reaction were traced by means of MCSCF/6-31G (210 configurations). The reaction activation energy of this reaction is 140.2KJ/mol. The reaction rate constants of five temperetures were calculated by CVT involving the tunneling effects.

CFD modeling using heterogeneous reaction kinetics for catalytic dehydrogenation syngas reactions in a fixed-bed reactor

A comprehensive 2D computational fluid dynamics （CFD） model was developed to simulate the flow behavior and catalytic dehydrogenation reaction of syngas in a heterogenous fixed-bed reactor （FBR）. The model combined the porous medium CFD model with a reaction kinetics model. To acquire an accu- rate reaction kinetics model, a comprehensive reaction mechanism was studied for the heterogeneous catalytic dehydrogenation reaction ofsyngas over a supported metal catalyst. Based on the reaction mech- anism and a statistical test, a reliable kinetics model was proposed. The CFD model combined with the above kinetics model was validated with one set of experimental data. The CFD model was also used to predict key reaction variable distributions such as the temperature and the component concentrations in the reactor.

Iron-nickel alloy particles with N-doped carbon “armor” as a highly selective and long-lasting catalyst for the synthesis of Nbenzylaniline molecules

A scalable strategy for the convenient and rapid preparation of nitrogen-doped carbon-coated iron-based alloy catalysts was developed.By controlling the type and amount of metal salts in the precursor,various types of nitrogen-doped carbon-coated alloy catalysts can be prepared in a targeted manner.Fe_(2)Ni2@CN materials with small particle sizes and relatively homogeneous basic sites showed promising results in the N-alkylation reaction of benzyl alcohol with aniline(optimum yield:99%).It is worth noting that the catalyst can also be magnetically separated and recovered after the reaction,and its performance can be regenerated through simple calcination.Furthermore,it was confirmed by kinetic experiments that the activation of C–H at the benzyl alcohol benzylic position is the rate-determining step(RDS).According to density flooding theory calculations,Fe_(2)Ni2@CN catalysts require less energy than other materials(Fe@CN and Ni@CN)for the RDS(dehydrogenation reaction)process.Therefore N-alkylation reactions are more easily carried out on Fe_(2)Ni2@CN catalysts,which may be the reason for the best catalytic activity of Fe-Ni alloy materials.These carbon-coated alloy materials will show great potential in more types of heterogeneous catalysis.

Palladium-Catalyzed Intramolecular Dehydrogenative Arylboration of Alkenes

The palladium-catalyzed borylative cyclization via C—H activation has been developed.By this chemistry,the indole-fused dihydro-pyrrole motif,which is a kind of important unit in natural products and bio-active molecules,could be constructed and installed with a boric ester group.Furthermore,the utilities of products have been illustrated by the study of further transformations.Importantly,by using chiral ligand,the enantioselectivity of this borylative cyclization reaction could be controlled.Moreover,the borylative mechanism,which should proceed through a Pd(II)/Pd(IV)catalytic cycle,has been proposed based on the DFT calculations.

β-Cyclodextrin Decorated CdS Nanocrystals Boosting the Photocatalytic Conversion of Alcohols

Regarding the utilization of semiconductor nanocrystals(NCs)in photocatalysis,the significant challenge is to eliminate the hindrance of decorated surface ligands on the photocarrier transport while maintaining their overall stability.Herein,we report a novel and stable catalyst comprising CdS NCs and surfacebound mono-(6-mercapto-6-deoxy)-β-cyclodextrin(HS-β-CD)molecules(denoted as CdS-CD),which could convert alcohols selectively into diols or aldehydes and H2 under visible light irradiation,with 100%atomutilization,using an aqueous medium as a green solvent.The decoratedβ-CD ligands did not only confer a good stability of CdS-CD in water but also showed a high host–guest affinity to the alcohol species,thereby,guaranteeing a close vicinity of alcohol molecules at the surface of CdS NCs and minimizing the hindrance of surface ligands on the photocarrier transport.As a result,the CdS-CD displayed much improved photocatalytic activity for the conversion of alcohols in aqueous media,compared with those of CdS-BF_(4)NCs.