Investigation of the stereodynamics of molecules and catalyzed reactions by CE

Abstract

The investigation of the molecular dynamics of stereoisomers and the study of the kinetics of reactions, in particular of catalyzed reactions, is of fundamental interest in chemistry, biochemistry, and medicine. Understanding how to control the transition state of a reaction allows for a directed design of new catalysts and benign processes. The integration of reactions and capillary or microchip-based electrophoretic separations is highly attractive to perform on-column derivatizations or enzymatic on-column digests of peptides and proteins for further characterization. The present review article focuses on the recent advances to study the stereodynamics of molecules and reaction kinetics of catalyzed processes by means of CE. Models and algorithms to evaluate interconversion profiles obtained by electrophoretic separation techniques are discussed with respect to the challenging demands of high separation efficiencies typical for electrophoretic techniques. Models used for evaluation are based on iterative computer simulation algorithms using the theoretical plate model or stochastic model of chromatography, empirical calculation methods, derived from equations used in chemical engineering, namely Damköhler analysis, and direct access with the approximation function and more recently with the unified equation, which can be applied to all kinds of first-order reactions taking place during a chromatographic or a electrophoretic separation. Furthermore, areas of applications are presented and discussed to give a guideline for using dynamic CE and on-column reaction electrophoresis to study kinetics of reactions and dynamic processes.

Comparative HPLC Enantioseparation of Thirty‐Six Aromatic Compounds on Four Columns of the Lux® Series: Impact of Substituents, Shapes and Electronic Properties

“…Concerning the enantioseparation capability of each CSP towards different series of compounds, CSP 1 showed to be suitable for the baseline separation of carbonyl and carboxyl analytes (four out of the six 30 , 31 , and 33 , 34 , 35 , 36 ), CSP 2 for alcohols (seven out of the ten 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 and 27 ) and for oxiranes (four out of the five 1 , 2 , 3 , 4 , 5 ), whereas CSP 4 for all five benzoin derivatives 6 , 7 , 8 , 9 and 32 and for the two diphenylphosphines 28 and 29 . Noteworthy, furoin ( 32 ) showed on‐column enantiomerization on CSP 3 and CSP 4 (Fig. ).…”

Stereodynamics of tetramezine

“…The interconversion barrier of the diaziridine units is typically greater than 80 kJ mol −1 ,25, 27, 28 which allows studying the stereodynamics by dynamic enantioselective chromatographic techniques 21, 29–41. Advantages are the necessity of only minute amounts of racemates, the possibility to simultaneously determine interconversion rate constants,42 and the superior precision to estimate activation parameters over broad temperature ranges.…”

Accuracy and sensitivity of the determination of rate constants of interconversion in achiral and chiral environments by dynamic enantioselective electrophoresis

“…The present state of art is discussed in several review papers [1][2][3][4]. Among others, electrophoretic methods enable us to use a wide variety of chiral selectors (CSs) such as cyclodextrins [5][6][7][8][9], macrocyclic antibiotics [9][10][11][12][13], crown ethers [9,[14][15][16][17], etc.…”