Void-column liquid chromatographic reactor studies to determine reaction rates in mobile and stationary phases

Chu, Alexander H.T.; Langer, Stanley H.

doi:10.1016/s0021-9673(01)94674-6

Cited by 8 publications

(4 citation statements)

References 22 publications

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“…(13), in our case they are ,1500-3000 s. When realizing that our separation times were ,1200-1500 s, it is clear that in our analyses the ratio between R-and S-enantiomers still did not reach the equilibrium given by Eq. (18). This is in fact an inherent consequence of the governing laws -the ratio between two interconverting enantiomers is not equal in the separation systems.…”

Section: Resultsmentioning

confidence: 99%

“…Equations (6) imply a hypothesis that when using otherwise the same separation systems differing only in the phase ratio, it should be possible to get more information on kinetic behavior of the separation system. The similar principle have already been used by Chu and Langer [18] in liquid chromatography, who inserted a void column between two packed columns to reach a various overall phase ratio. In this way these authors determined rate constants of some reactions both in liquid and stationary phase.…”

Section: General Aspectsmentioning

confidence: 96%

See 1 more Smart Citation

Dynamics of interconversion of enantiomers in chiral separation systems: A novel approach for determination of all rate constants involved in the interconversion

2004

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When enantiomers separated by chromatography or capillary electrophoresis undergo interconversion reaction (enantiomerization) during the separation, it leads to a typical detection pattern: two individual peaks of the separated enantiomers are connected with a plateau consisting of a mixture of both separated enantiomers. We propose a separation method for determination of all individual rate constants (or inversion barriers) of the interconversion. The method enables to distinguish which part of interconversion takes place in the free (unbound) form of the analyte and which part in the complexed (bound) form. Further, we propose a complete dynamic model of capillary electrophoresis of interconverting enantiomers based on solving a complete set of continuity equations for all constituents of the separation system together with complexation and acid-base equilibria. This allows a simulation of both linear and nonlinear mode of separation and understanding all processes taking place in such enantioseparation systems. We demonstrate the applicability of the method on determination of the rate constants of interconversion of oxazepam enantiomers separated in systems with charged cyclodextrin chiral selectors.

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Section: Resultsmentioning

confidence: 99%

Section: General Aspectsmentioning

confidence: 96%

Dynamics of interconversion of enantiomers in chiral separation systems: A novel approach for determination of all rate constants involved in the interconversion

2004

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“…where the peak area of void product formation is given by A n , C 1 and C 2 are empirical constants, t n represents the residence time in the void column, and k m,n and k m,c are the mobile phase kinetic rate constants in the void and the packed column, respectively [109,110]. If the assumption of the ideal chromatographic reactor no longer holds, equations to evaluate the chromatogram taking into account adsorption -desorption kinetics or axial dispersion can be found in the literature [111].…”

Section: Determination Of Rate Constantsmentioning

confidence: 99%

Chromatographic Reactors

Fricke¹,

Schmidt–Traub²,

Schembecker³

2008

Ullmann's Encyclopedia of Industrial Chemistry

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Chromatographic reactors integrate chemical reaction and chromatographic separation in one apparatus. This offers potential for process intensification, especially in the case of equilibrium reactions. Different types of discontinuous and continuous processes as well as modeling of chromatographic reactors are described. Synthesis and design of this processes is very much influenced and often restricted by the type of reaction and the operating window which is set by the individual operating conditions for chemical reaction, mass separation, and equipment design. Integrated chromatographic reactors should be considered if chromatography is the favored separation process for a conventional sequential process design. Preparative chromatographic reactors are known for liquid‐ and gas‐phase processes. Laboratory‐scale applications are described. Analytical chromatographic reactors are used to determine reaction rate constants and kinetics, and to screen chromatographic systems and operating conditions for preparative applications. 1. Introduction 2. Types of Chromatographic Reactors 3. Modeling of Chromatographic Reactors 3.1. Adsorption Isotherm and Reaction Kinetics 3.2. Modeling the BCR 3.3. Modeling Simulated Moving Bed Chromatographic Reactors 3.4. Process control 4. Synthesis of Preparative Chromatographic Reactors 4.1. Process Principles 4.2. Type of Reaction 5. Design of Preparative Chromatographic Reactors 5.1. Design of the Process 5.2. Choice of Operating Conditions 6. Preparative Chromatographic Reactors 6.1. Applications of Gas Chromatographic Reactors 6.2. Application of Liquid Chromatographic Reactors 7. Analytical Chromatographic Reactors 7.1. Determination of Rate Constants 7.2. Enzymatic Reactions 7.3. Characterization of the Stationary Phase 7.4. Examination of Fast Equilibrium Reactions 7.5. Examination of Solvent Effects

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“…This problem can be circumvented by using a special HPLC-setup consisting of two identical chromatographic columns connected by an empty capillary with a considerable dead volume, originally invented by Chu and Langer. [2] The resulting chromatograms are typically characterized by an extra peak containing the full kinetic information from the reaction in the homogenous capillary zone. In two preceding publications, [3,4] deconvolution of the reaction chromatogram of first order irreversible and reversible reactions with identical rate constants, was demonstrated.…”

Section: Introductionmentioning

confidence: 99%