The Experts below are selected from a list of 354603 Experts worldwide ranked by ideXlab platform
Lei Jiang - One of the best experts on this subject based on the ideXlab platform.
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mass transfer limitations for immobilized enzyme catalyzed kinetic Resolution of racemate in a fixed bed reactor
Biotechnology and Bioengineering, 2001Co-Authors: Guohua Xiu, Lei JiangAbstract:A mathematical model has been developed for immobilized enzyme-catalyzed kinetic Resolution of racemate in a fixed-bed reactor in which the enzyme-catalyzed reaction (the irreversible uni-uni competitive Michaelis-Menten kinetics is chosen as an example) was coupled with intraparticle diffusion, external mass transfer, and axial dispersion. The effects of mass-transfer limitations, competitive inhibition of substrates, deactivation on the enzyme effective enantioselectivity, and the optical purity and yield of the desired product are examined quantitatively over a wide range of parameters using the orthogonal collocation method. For a first-order reaction, an analytical solution is derived from the mathematical model for slab-, cylindrical-, and spherical-enzyme supports. Based on the analytical solution for the steady-state Resolution Process, a new concise formulation is presented to predict quantitatively the mass-transfer limitations on enzyme effective enantioselectivity and optical purity and yield of the desired product for a continuous steady-state kinetic Resolution Process in a fixed-bed reactor.
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mass transfer limitations for immobilized enzyme catalyzed kinetic Resolution of racemate in a batch reactor
Industrial & Engineering Chemistry Research, 2000Co-Authors: Guohua Xiu, Lei JiangAbstract:The immobilized enzyme-catalyzed kinetic Resolution of racemate in a batch reactor was studied theoretically. An exact solution was developed for a first-order reaction coupled with the intraparticle and external mass transfers. The time courses of substrate concentration and conversion as well as the purity and yield of the desired product were predicted by the exact solution, and the effects of the intraparticle and external mass-transfer resistances on the enzyme enantioselectivity were also quantitatively discussed. A simple approximate solution, taking into account the simultaneous reaction/external and intraparticle mass-transfer Processes for the immobilized enzyme, was presented to predict the purity and yield of the desired product. For a competitive Michaelis-Menten kinetic Resolution Process, the effects of the competitive inhibitions of substrate and free water on the Resolution Process were analyzed by the orthogonal collocation method. The effectiveness factor and the effective enantiomeric ratio were predicted by the domain division method for the simplest case that the Resolution Process is at pseudo steady state and the inhibition effect of free water can be neglected.
Guohua Xiu - One of the best experts on this subject based on the ideXlab platform.
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mass transfer limitations for immobilized enzyme catalyzed kinetic Resolution of racemate in a fixed bed reactor
Biotechnology and Bioengineering, 2001Co-Authors: Guohua Xiu, Lei JiangAbstract:A mathematical model has been developed for immobilized enzyme-catalyzed kinetic Resolution of racemate in a fixed-bed reactor in which the enzyme-catalyzed reaction (the irreversible uni-uni competitive Michaelis-Menten kinetics is chosen as an example) was coupled with intraparticle diffusion, external mass transfer, and axial dispersion. The effects of mass-transfer limitations, competitive inhibition of substrates, deactivation on the enzyme effective enantioselectivity, and the optical purity and yield of the desired product are examined quantitatively over a wide range of parameters using the orthogonal collocation method. For a first-order reaction, an analytical solution is derived from the mathematical model for slab-, cylindrical-, and spherical-enzyme supports. Based on the analytical solution for the steady-state Resolution Process, a new concise formulation is presented to predict quantitatively the mass-transfer limitations on enzyme effective enantioselectivity and optical purity and yield of the desired product for a continuous steady-state kinetic Resolution Process in a fixed-bed reactor.
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mass transfer limitations for immobilized enzyme catalyzed kinetic Resolution of racemate in a batch reactor
Industrial & Engineering Chemistry Research, 2000Co-Authors: Guohua Xiu, Lei JiangAbstract:The immobilized enzyme-catalyzed kinetic Resolution of racemate in a batch reactor was studied theoretically. An exact solution was developed for a first-order reaction coupled with the intraparticle and external mass transfers. The time courses of substrate concentration and conversion as well as the purity and yield of the desired product were predicted by the exact solution, and the effects of the intraparticle and external mass-transfer resistances on the enzyme enantioselectivity were also quantitatively discussed. A simple approximate solution, taking into account the simultaneous reaction/external and intraparticle mass-transfer Processes for the immobilized enzyme, was presented to predict the purity and yield of the desired product. For a competitive Michaelis-Menten kinetic Resolution Process, the effects of the competitive inhibitions of substrate and free water on the Resolution Process were analyzed by the orthogonal collocation method. The effectiveness factor and the effective enantiomeric ratio were predicted by the domain division method for the simplest case that the Resolution Process is at pseudo steady state and the inhibition effect of free water can be neglected.
Florence Sedes - One of the best experts on this subject based on the ideXlab platform.
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a framework to manage knowledge from defect Resolution Process
Congress on Evolutionary Computation, 2011Co-Authors: Gregory Claude, Marc Boyer, Gael Durand, Florence SedesAbstract:This paper presents a framework for the management, the Processing and the reuse, of information relative to defects. This framework is based on the fact that each defect triggers a Resolution Process in which information about the detected incident (i.e. the problem) and about the applied protocol to resolve it (i.e. the solution) is collected. These different types of information are the cornerstone of the optimization of corrective and preventive Processes for new defects. Experimentations show that our prototype provides a very satisfactory quality of results with good performances.
Shikai Tian - One of the best experts on this subject based on the ideXlab platform.
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kinetic Resolution of racemic allylic alcohols by catalytic asymmetric substitution of the oh group with monosubstituted hydrazines
Chemistry: A European Journal, 2016Co-Authors: Liang Yan, Chaofan Huang, Shikai TianAbstract:A new strategy has been established for the kinetic Resolution of racemic allylic alcohols through a palladium/sulfonyl-hydrazide-catalyzed asymmetric OH-substitution under mild conditions. In the presence of 1 mol % [Pd(allyl)Cl]2 , 4 mol % (S)-SegPhos, and 10 mol % 2,5-dichlorobenzenesulfonyl hydrazide, a range of racemic allylic alcohols were smoothly resolved with selectivity factors of more than 400 through an asymmetric allylic alkylation of monosubstituted hydrazines under air at room temperature. Importantly, this kinetic Resolution Process provided various allylic alcohols and allylic hydrazine derivatives with high enantiopurity.
Andrea Temperini - One of the best experts on this subject based on the ideXlab platform.
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a chiral electrophilic selenium reagent to promote the kinetic Resolution of racemic allylic alcohols
Organic Letters, 2004Co-Authors: Marcello Tiecco, Lorenzo Testaferri, Claudio Santi, Cristina Tomassini, Rosaria Bonini, Francesca Marini, Luana Bagnoli, Andrea TemperiniAbstract:The first example of a kinetic Resolution Process promoted by electrophilic selenium reagents is reported. Racemic allylic alcohols react with half equivalents of a selenenylating agent in methanol leading to the regiospecific formation of the corresponding addition products with a very high level of facial selectivity (from 95:5 to 98:2 dr). The unreacted alcohols can be recovered in an optically enriched form (from 90 to 94% ee).
