Determination of Enantiomeric Excess in Samples of Chiral Molecules Using Fourier Transform Vibrational Circular Dichroism Spectroscopy: Simulation of Real-Time Reaction Monitoring
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- 作者：Changning Guo ; Rekha D. Shah ; Rina K. Dukor ; Xiaolin Cao ; Teresa B. Freedman ; and Laurence A. Nafie
- 刊名：Analytical Chemistry
- 出版年：2004
- 出版时间：December 1, 2004
- 年：2004
- 卷：76
- 期：23
- 页码：6956 - 6966
- 全文大小：202K
- 年卷期：v.76,no.23(December 1, 2004)
- ISSN：1520-6882
文摘
The first use of Fourier transform vibrational circulardichroism (FT-VCD) to follow changes in the percentenantiomeric excess (% EE) of chiral molecules in timeusing a flow cell sampling apparatus is reported. FT-VCD,as opposed to dispersive scanning VCD, eliminates theneed to scan the VCD spectrum in time to monitor the %EE at more than one spectral location. The first use ofpartial least-squares chemometric analysis to determine% EE values from kinetic sets of VCD spectral data is alsoreported. These two advances have been used to monitorsimultaneously changes in the fractional composition andthe % EE of a mixture of two different chiral molecules.This simulates the progress of the chemical reaction froma chiral reactant to a chiral product where the % EE ofboth molecules can change with time. For the moleculesstudied, 
-pinene, camphor, and borneol, the accuracyof following % EE changes for one species alone is ~1%,while for simultaneously following % EE changes in twospecies is ~2% for 10-20-min sampling periods at 4cm-1 spectral resolution. This accuracy can be increasedfor the same collection times or maintained for shorterperiods of collection by lowering the spectral resolution.These findings demonstrate the potential for VCD to beused for real-time monitoring of the composition and %EE of chemical reactions involving the synthesis chiralmolecules.
-pinene, camphor, and borneol, the accuracyof following % EE changes for one species alone is ~1%,while for simultaneously following % EE changes in twospecies is ~2% for 10-20-min sampling periods at 4cm-1 spectral resolution. This accuracy can be increasedfor the same collection times or maintained for shorterperiods of collection by lowering the spectral resolution.These findings demonstrate the potential for VCD to beused for real-time monitoring of the composition and %EE of chemical reactions involving the synthesis chiralmolecules.