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Fast and precise access to enantiomerization rate constants in dynamic chromatography
Author(s) -
Trapp O.
Publication year - 2006
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20276
Subject(s) - chemistry , chromatography , reaction rate constant , computational chemistry , kinetics , classical mechanics , physics
An analytical solution of the unified equation to evaluate elution profiles of interconverting enantiomers in dynamic chromatography is presented. Rate constants k 1 and k −1 and Gibbs activation energies are directly obtained from the chromatographic parameters (retention times t R Aand t R Aof the interconverting enantiomers, the peak widths at half height w A and w B , and the relative plateau height h p ), and the initial amounts A 0 and B 0 of the enantiomers without any iterative and time consuming computational step. Therefore, this equation is no longer limited to racemic analytes. The analytical solution presented here was validated by comparison with a dataset of 125,000 simulated elution profiles of enantiomerizations. Furthermore, it was found that the recovery rate from a defined dataset is on average 40% higher using the unified equation compared to evaluation methods based on iterative computer simulation. The new equation was applied to determine the enantiomerization rate constant of 1‐ n ‐butyl‐2‐ tert ‐butyldiaziridine by enantioselective gas chromatography. The activation parameters (Δ H ‡ = 112.6 ± 2.5 kJ/mol and Δ S ‡ = −27 ± 2 J/(K mol) were obtained from temperature‐dependent measurements between 100°C and 140°C in 10K steps. Chirality 18:489–497, 2006. © 2006 Wiley‐Liss, Inc.