Measurements of concentration dependence and enantiomeric purity of terpene solutions as a test of a new commercial VCD spectrometer

Abstract

Vibrational circular dichroism (VCD) spectra of (+)‐α‐pinene solutions in carbon tetrachloride have been measured in the range of volume fractions 5–100% (v/v) in the mid‐infrared region. The concentration dependence measured was statistically analyzed with the aim of obtaining a reliable correlation between the VCD band areas and the concentrations of individual enantiomers. The quality of the spectra was estimated by means of noise spectra which were defined as half the difference of the two following blocks of scans. In addition to this, the enantiomeric purity was studied. This study was carried out for both (+)‐ and (−)‐α‐pinene enantiomers in the range of the percent enantiomeric excess in the interval 10–100%. The relationship between VCD intensity and enantiomeric purity was determined by least‐square regression and statistically evaluated. All measurements performed in this study were intended as a basic tool for testing of a new commercial VCD setup from Bruker. Chirality 12:199–203, 2000. © 2000 Wiley‐Liss, Inc.

Mini review: Instrumentation for vibrational circular dichroism spectroscopy, still a role for dispersive instruments

“…Fourier transform infrared‐vibrational circular dichroism spectrometers have been developed in several labs with varying designs developed and expanded from the initial concepts of Nafie and co‐workers . Virtually all use a commercial FTIR (separate or internally integrated) as a source of modulated (by interferometry) IR light, then add polarization optics and processing electronics and software to realize VCD measurement.…”

“…Subsequently, a fundamental change in the methodology came about built on the pioneering work of Nafie and co‐workers in their development of Fourier transform based VCD instrumentation. Several labs picked up on these ideas, and modified those designs, but the work of the Syracuse group, and its subsequent evolution to a commercial platform, has revolutionized VCD measurements and made them truly widespread …”

Vibrational circular dichroism of 3‐(trifluoroacetyl)‐camphor and its interaction with chiral amines

“…Vibrational circular dichroism (VCD) spectroscopy has proven to be a useful tool for the determination of the absolute configuration1–4 and the preferred conformation of small chiral molecules in solution, especially natural products such as Camphor and its derivatives 5–9. Investigations of weak interactions like hydrogen bonding that lead to the formation of molecular adducts were also shown to be possible 10.…”

Towards the Limits of Vibrational Circular Dichroism Spectroscopy: VCD Spectra of Some Alkyl Vinylethers

“…VCD spectra were recorded using a Jasco (Tokyo, Japan) FVS 6000 VCD spectrometer (6000–8000 scans). The instrument performance was checked using CCl 4 solutions of (+) and (–)‐camphor and (+) and (–)‐limonene, used as standards, just before measuring the samples. The samples were measured in CCl 4 solution (0.6 and 0.3 M) in a 100 µm KBr cell.…”