Chiroptical Properties of 2-Chloropropionitrile

(S)-(−)-2-Chloropropionitrile has been prepared from (S)-(+)-alanine, and the ORD curves have been obtained in several solvents and in the gas phase. A reaction field extrapolation of the solution data to the gas phase led to an estimated value of [α]D = −21°, whereas the interpolated gas phase value is −8°. The specific rotation was found to be temperature dependent in ethylcyclohexane solution over the range 0−100 °C. Although rotation of the methyl group leads to large calculated effects on the specific rotation, it does not lead to the temperature dependence. Rather, a low frequency mode at 224 cm-1 was found to be responsible. This is a mixed mode involving methyl torsion and CC⋮N bending. The specific rotations calculated at the B3LYP/aug-cc-pVDZ level including electric field dependent functions are in very good agreement with the measured gas phase values.