The Interpretation of the Vibrational Spectra of the C6 Hydrocarbons 22-Dimethyl Butane, 22-Dimethyl−3-Butene, and 22-Dimethyl−3-Butyne

Assignments have been made for the observed infra-red and Raman frequencies of the molecules 22-dimethyl butane, 22-dimethyl−3-butene, and 22-dimethyl−3-butyne. By using the previously assigned characteristic frequency regions associated with the ethyl, vinyl, and C≡CH groups, it has been shown that the tertiary butyl group in all these molecules has frequencies near 1250, 1210(2), 1025(2), 880, and 700 cm−1, in the range 1350–600 cm−1. The assignment of these frequencies to skeletal C–C stretching and to methyl wagging modes is discussed.