A profound influence of water has previously been detected in the complexation of the enantiomers of methyl 2-chloropropanoate (MCP) and the chiral selector octakis(3-O-butanoyl-2,6-di-O-pentyl)-γ-cyclodextrin (Lipodex-E) in NMR and sensor experiments. We therefore investigated the retention behavior of MCP enantiomers on Lipodex-E by gas chromatography (GC) under hydrous conditions. Addition of water to the N2 carrier gas modestly reduced the retention factors k of the enantiomers, notably for the second eluted enantiomer (S)-MCP. This resulted in an overall decrease of enantioselectivity -ΔS,R(ΔG) in the presence of water. The effect was fully reversible. Consequently, for a conditioned column in the absence of residual water, the determined thermodynamic data, i.e. ΔS,R(ΔH) = -12.64 ± 0.08 kJ mol-1 and ΔS,R(ΔS) = -28.18 ± 0.23 J K-1 mol-1, refer to a true 1:1 complexation process devoid of hydrophobic hydration. Chirality 28:124-131, 2015.

Separation of Enantiomers by Inclusion Gas Chromatography: On the Influence of Water in the Molecular Complexation of Methyl 2-Chloropropanoate Enantiomers and the Modified γ-Cyclodextrin Lipodex-E

MANDOLI, ALESSANDRO
;
2016-01-01

Abstract

A profound influence of water has previously been detected in the complexation of the enantiomers of methyl 2-chloropropanoate (MCP) and the chiral selector octakis(3-O-butanoyl-2,6-di-O-pentyl)-γ-cyclodextrin (Lipodex-E) in NMR and sensor experiments. We therefore investigated the retention behavior of MCP enantiomers on Lipodex-E by gas chromatography (GC) under hydrous conditions. Addition of water to the N2 carrier gas modestly reduced the retention factors k of the enantiomers, notably for the second eluted enantiomer (S)-MCP. This resulted in an overall decrease of enantioselectivity -ΔS,R(ΔG) in the presence of water. The effect was fully reversible. Consequently, for a conditioned column in the absence of residual water, the determined thermodynamic data, i.e. ΔS,R(ΔH) = -12.64 ± 0.08 kJ mol-1 and ΔS,R(ΔS) = -28.18 ± 0.23 J K-1 mol-1, refer to a true 1:1 complexation process devoid of hydrophobic hydration. Chirality 28:124-131, 2015.
2016
Mandoli, Alessandro; Schurig, Volker
File in questo prodotto:
File Dimensione Formato  
Mandoli_790478_1.pdf

Open Access dal 01/03/2017

Tipologia: Documento in Post-print
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 707.06 kB
Formato Adobe PDF
707.06 kB Adobe PDF Visualizza/Apri
Mandoli_790478_2.pdf

Open Access dal 01/03/2017

Descrizione: Supporting Information
Tipologia: Altro materiale allegato
Licenza: Creative commons
Dimensione 220.02 kB
Formato Adobe PDF
220.02 kB Adobe PDF Visualizza/Apri

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/11568/790478
Citazioni
  • ???jsp.display-item.citation.pmc??? 0
  • Scopus 2
  • ???jsp.display-item.citation.isi??? 2
social impact