The determination of enantiomeric purity and absolute configuration by vibrational circular dichroism spectroscopy

There is an increasing need for new methods to determine percent enantiomeric excess (%ee) in chiral molecules. Four sets of determinations of %ee using Fourier transform infrared vibrational circular dichroism (FTIR-VCD) have been performed using three different instruments and several kinds of samples. These include measurements for neat ol-pinene with two different FTIR spectrometers equipped with a mercury cadmium telluride (MCT) detector, measurements for lysine in H2O using one of the MCT instruments, and measurements for 3-methylcyclohexanone in CCl4 solution. We find that FT-VCD spectroscopy is capable of measuring %ee in the range of 1% or better for these samples using one to several hours of spectral collection time.