The Experts below are selected from a list of 234 Experts worldwide ranked by ideXlab platform
Anand V Patwardhan - One of the best experts on this subject based on the ideXlab platform.
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reaction of Benzyl Chloride with ammonium sulfide under liquid liquid phase transfer catalysis reaction mechanism and kinetics
Journal of Molecular Catalysis A-chemical, 2006Co-Authors: Sunil K Maity, Narayan C Pradhan, Anand V PatwardhanAbstract:Abstract The reaction between Benzyl Chloride and aqueous ammonium sulfide was carried out in an organic solvent – toluene, using tetrabutylammonium bromide (TBAB) as phase transfer catalyst (PTC). Two products, namely diBenzyl sulfide (DBS) and Benzyl mercaptan (BM), were identified in the reaction mixture. The selectivity of DBS was maximised by changing various parameters such as NH3/H2S mole ratio, stirring speed, catalyst loading, concentration of Benzyl Chloride, volume of aqueous phase, and temperature. The highest selectivity of DBS obtained was about 90% after 445 min of reaction with excess Benzyl Chloride at 60 °C. Complete conversion of Benzyl Chloride could be achieved at the cost of very low selectivity of DBS and very high selectivity of BM. The apparent activation energy for the kinetically controlled reaction was found to be 12.3 kcal/mol. From the detailed study of the effects of various parameters on the reaction, a suitable mechanism was established which could explain the course of the reaction.
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Reaction of Benzyl Chloride with ammonium sulfide under liquid–liquid phase transfer catalysis: Reaction mechanism and kinetics
Journal of Molecular Catalysis A-chemical, 2006Co-Authors: Sunil K Maity, Narayan C Pradhan, Anand V PatwardhanAbstract:Abstract The reaction between Benzyl Chloride and aqueous ammonium sulfide was carried out in an organic solvent – toluene, using tetrabutylammonium bromide (TBAB) as phase transfer catalyst (PTC). Two products, namely diBenzyl sulfide (DBS) and Benzyl mercaptan (BM), were identified in the reaction mixture. The selectivity of DBS was maximised by changing various parameters such as NH3/H2S mole ratio, stirring speed, catalyst loading, concentration of Benzyl Chloride, volume of aqueous phase, and temperature. The highest selectivity of DBS obtained was about 90% after 445 min of reaction with excess Benzyl Chloride at 60 °C. Complete conversion of Benzyl Chloride could be achieved at the cost of very low selectivity of DBS and very high selectivity of BM. The apparent activation energy for the kinetically controlled reaction was found to be 12.3 kcal/mol. From the detailed study of the effects of various parameters on the reaction, a suitable mechanism was established which could explain the course of the reaction.
Christian Amatore - One of the best experts on this subject based on the ideXlab platform.
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bridging the gap between electrochemical and organometallic activation Benzyl Chloride reduction at silver cathodes
Journal of the American Chemical Society, 2010Co-Authors: Yifan Huang, Deyin Wu, An Wang, S Rondinini, Zhongqun Tian, Christian AmatoreAbstract:Integration of voltammetry, surface-enhanced Raman spectroscopy (SERS), and density functional theory (DFT) has allowed unraveling the mechanistic origin of the exceptional electrocatalytic properties of silver cathodes during the reduction of Benzyl Chloride. At inert electrodes the initial reduction proceeds through a concerted direct electron transfer yielding a Benzyl radical as the first intermediate. Conversely, at silver electrodes it involves an uphill preadsorption of Benzyl Chloride onto the silver cathode. Reduction of this adduct affords a species tentatively described as a distorted Benzyl radical anion stabilized by the silver surface. This transient species rapidly evolves to yield ultimately a Benzyl radical bound onto the silver surface, the latter being reduced into a Benzyl−silver anionic adduct which eventually dissociates into a free Benzyl anion at more negative potentials. Within this framework, the exceptional electrocatalytic properties of silver cathodes stem from the fact that t...
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in situ identification of intermediates of Benzyl Chloride reduction at a silver electrode by sers coupled with dft calculations
Journal of the American Chemical Society, 2010Co-Authors: An Wang, Yifan Huang, Deyin Wu, S Rondinini, Christian Amatore, Zhongqun TianAbstract:Aiming to deeply understand the electrocatalytic mechanism of silver on reduction of Benzyl Chloride, we carried out an in situ electrochemical surface-enhanced Raman spectroscopic study to characterize various surface species in different electrode potential regions. A further analysis with DFT calculation reveals that the Benzyl radical and its anionic derivate bonded on a silver electrode are the key intermediates, implying that the pathway could drastically differ from the outer sphere concerted electron reduction at inert electrodes.
Lei Wu - One of the best experts on this subject based on the ideXlab platform.
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relaxation mechanisms in a Benzyl Chloride toluene glass
Physical Review B, 1991Co-Authors: Lei WuAbstract:Using frequency-dependent dielectric susceptibility, we have studied three different types of relaxation phenomena, namely primary (\ensuremath{\alpha}), secondary (\ensuremath{\beta}), and conductivity (c) relaxation, in a sample of 25 vol % Benzyl Chloride in toluene. The measurement covers ten decades of frequency: ${10}^{\mathrm{\ensuremath{-}}3}$${10}^{7}$ Hz. The conductivity relaxation which is due to mobile ionic impurities in the sample has characteristics similar to those of the primary relaxation. Using the universal scaling curve for the primary relaxation response in glasses, we can separate the primary and secondary relaxations which overlap in frequency. The shape of the secondary relaxation is log-normal in the frequency domain and corresponds to a Gaussian distribution of energy barriers. The relaxation time for this process can be fitted by an Arrhenius form. Extrapolating the data to higher temperatures, we find that it crosses the primary-relaxation curve. We compare a set of similar molecular liquids and conclude that the secondary relaxation is mainly due to the rotation of a subgroup in the Benzyl Chloride molecule. We also report a measurement of the nonlinear dielectric response. There is no evidence of a divergent nonlinear susceptibility as the glass transition is approached.
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Relaxation mechanisms in a Benzyl Chloride–toluene glass
Physical Review B, 1991Co-Authors: Lei WuAbstract:Using frequency-dependent dielectric susceptibility, we have studied three different types of relaxation phenomena, namely primary (\ensuremath{\alpha}), secondary (\ensuremath{\beta}), and conductivity (c) relaxation, in a sample of 25 vol % Benzyl Chloride in toluene. The measurement covers ten decades of frequency: ${10}^{\mathrm{\ensuremath{-}}3}$${10}^{7}$ Hz. The conductivity relaxation which is due to mobile ionic impurities in the sample has characteristics similar to those of the primary relaxation. Using the universal scaling curve for the primary relaxation response in glasses, we can separate the primary and secondary relaxations which overlap in frequency. The shape of the secondary relaxation is log-normal in the frequency domain and corresponds to a Gaussian distribution of energy barriers. The relaxation time for this process can be fitted by an Arrhenius form. Extrapolating the data to higher temperatures, we find that it crosses the primary-relaxation curve. We compare a set of similar molecular liquids and conclude that the secondary relaxation is mainly due to the rotation of a subgroup in the Benzyl Chloride molecule. We also report a measurement of the nonlinear dielectric response. There is no evidence of a divergent nonlinear susceptibility as the glass transition is approached.
Marcelo Navarro - One of the best experts on this subject based on the ideXlab platform.
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electrochemical reduction of Benzyl Chloride on silver graphite and silver graphite powder macroelectrodes
Electrochimica Acta, 2015Co-Authors: Ronny F M De Souza, Michel Laurent, Eric Leonel, Christine Cachetvivier, Carlos A F De Souza, Madalena C C Areias, Lothar W Bieber, Marcelo NavarroAbstract:Abstract Benzyl Chloride reduction was studied in a powder macroelectrode (PME) made of silver, graphite or silver/graphite mixtures (1:3, 1:1 and 3:1) in absence of solvent, or using a very low amount of DMF as solvent (PhCH 2 Cl/DMF 3:1). A 0.1 mol L −1 KCl aqueous solution was used as anolyte. A competitive hydrogenation and dimerization process was observed, affording the respective toluene and biBenzyl products. The well-known electrocatalytic effect of silver on reduction of the C Cl bond was confirmed by a significant positive shift of the Benzyl Chloride reduction potential in comparison with pure graphite powder. The products distribution was analysed after linear sweep voltammetries at low scan rate (0.1 mV s −1 ), indicating high yields of biBenzyl produced on Ag/graphite-PME. Pure graphite-PME was not selective towards dimer formation. The best results for biBenzyl production occurred at more positive potentials, in the presence of silver. A small amount of solvent (DMF) play an important role on the electrode surface desorption and diffusion of intermediary species.
Zhongqun Tian - One of the best experts on this subject based on the ideXlab platform.
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bridging the gap between electrochemical and organometallic activation Benzyl Chloride reduction at silver cathodes
Journal of the American Chemical Society, 2010Co-Authors: Yifan Huang, Deyin Wu, An Wang, S Rondinini, Zhongqun Tian, Christian AmatoreAbstract:Integration of voltammetry, surface-enhanced Raman spectroscopy (SERS), and density functional theory (DFT) has allowed unraveling the mechanistic origin of the exceptional electrocatalytic properties of silver cathodes during the reduction of Benzyl Chloride. At inert electrodes the initial reduction proceeds through a concerted direct electron transfer yielding a Benzyl radical as the first intermediate. Conversely, at silver electrodes it involves an uphill preadsorption of Benzyl Chloride onto the silver cathode. Reduction of this adduct affords a species tentatively described as a distorted Benzyl radical anion stabilized by the silver surface. This transient species rapidly evolves to yield ultimately a Benzyl radical bound onto the silver surface, the latter being reduced into a Benzyl−silver anionic adduct which eventually dissociates into a free Benzyl anion at more negative potentials. Within this framework, the exceptional electrocatalytic properties of silver cathodes stem from the fact that t...
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in situ identification of intermediates of Benzyl Chloride reduction at a silver electrode by sers coupled with dft calculations
Journal of the American Chemical Society, 2010Co-Authors: An Wang, Yifan Huang, Deyin Wu, S Rondinini, Christian Amatore, Zhongqun TianAbstract:Aiming to deeply understand the electrocatalytic mechanism of silver on reduction of Benzyl Chloride, we carried out an in situ electrochemical surface-enhanced Raman spectroscopic study to characterize various surface species in different electrode potential regions. A further analysis with DFT calculation reveals that the Benzyl radical and its anionic derivate bonded on a silver electrode are the key intermediates, implying that the pathway could drastically differ from the outer sphere concerted electron reduction at inert electrodes.
