Clobazam, a 1,5-benzodiazepin-2,4-dione, is a chiral molecule because its ground state conformation features a nonplanar seven-membered ring lacking reflection symmetry elements. The two conformational enantiomers of clobazam interconvert at room temperature by a simple ring-flipping process. Variable temperature HPLC on the Pirkle type (R)-N-(3,5-dinitronenzoyl)phenylglycine and (R,R)-Whelk-O1 chiral stationary phases (CSPs) allowed us to separate for the first time the conformational enantiomers of clobazam and to observe peak coalescence-decoalescence phenomena due to concomitant separation and interconversion processes occurring on the same time scale. Clobazam showed temperature dependent dynamic high-performance liquid chromatography (HPLC) profiles with interconversion plateaus on the two CSPs indicative of on-column enantiomer interconversion. (enantiomerization) in the column temperature range between Tcol = 10°C and Tcol = 30°C, whereas on-column interconversion was absent at temperature close to or lower than Tcol = 5°C. Computer simulation of exchange-deformed HPLC profiles using a program based on the stochastic model yielded the apparent rate constants for the on-column enantiomerization and the corresponding free energy activation barriers. At Tcol = 20°C the averaged enantiomerization barriers, ΔG(‡) , for clobazam were found in the range 21.08-21.53 kcal mol(-1) on the two CSPs. The experimental dynamic chromatograms and the corresponding interconversion barriers reported in this article are consistent with the literature data measured by DNMR at higher temperatures and in different solvents.

Dynamic behavior of clobazam on high-performance liquid chromatography chiral stationary phases / Sabia, Rocchina; Martino, MICHELA DE; Cavazzini, Alberto; Villani, Claudio. - In: CHIRALITY. - ISSN 0899-0042. - STAMPA. - 28:1(2016), pp. 17-21. [10.1002/chir.22542]

Dynamic behavior of clobazam on high-performance liquid chromatography chiral stationary phases

SABIA, ROCCHINA;CAVAZZINI, ALBERTO;VILLANI, Claudio
2016

Abstract

Clobazam, a 1,5-benzodiazepin-2,4-dione, is a chiral molecule because its ground state conformation features a nonplanar seven-membered ring lacking reflection symmetry elements. The two conformational enantiomers of clobazam interconvert at room temperature by a simple ring-flipping process. Variable temperature HPLC on the Pirkle type (R)-N-(3,5-dinitronenzoyl)phenylglycine and (R,R)-Whelk-O1 chiral stationary phases (CSPs) allowed us to separate for the first time the conformational enantiomers of clobazam and to observe peak coalescence-decoalescence phenomena due to concomitant separation and interconversion processes occurring on the same time scale. Clobazam showed temperature dependent dynamic high-performance liquid chromatography (HPLC) profiles with interconversion plateaus on the two CSPs indicative of on-column enantiomer interconversion. (enantiomerization) in the column temperature range between Tcol = 10°C and Tcol = 30°C, whereas on-column interconversion was absent at temperature close to or lower than Tcol = 5°C. Computer simulation of exchange-deformed HPLC profiles using a program based on the stochastic model yielded the apparent rate constants for the on-column enantiomerization and the corresponding free energy activation barriers. At Tcol = 20°C the averaged enantiomerization barriers, ΔG(‡) , for clobazam were found in the range 21.08-21.53 kcal mol(-1) on the two CSPs. The experimental dynamic chromatograms and the corresponding interconversion barriers reported in this article are consistent with the literature data measured by DNMR at higher temperatures and in different solvents.
2016
atropisomers; benzodiazepines; conformational enantiomers; dynamic chiral chromatography; enantiomerization barriers
01 Pubblicazione su rivista::01a Articolo in rivista
Dynamic behavior of clobazam on high-performance liquid chromatography chiral stationary phases / Sabia, Rocchina; Martino, MICHELA DE; Cavazzini, Alberto; Villani, Claudio. - In: CHIRALITY. - ISSN 0899-0042. - STAMPA. - 28:1(2016), pp. 17-21. [10.1002/chir.22542]
File allegati a questo prodotto
File Dimensione Formato  
Sabia_Dynamic_2016.pdf

solo gestori archivio

Note: Articolo principale
Tipologia: Versione editoriale (versione pubblicata con il layout dell'editore)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 534.26 kB
Formato Adobe PDF
534.26 kB Adobe PDF   Contatta l'autore

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/875441
Citazioni
  • ???jsp.display-item.citation.pmc??? 1
  • Scopus 14
  • ???jsp.display-item.citation.isi??? 13
social impact