The Assignment of the Vibrational Spectra of the C4 Hydrocarbons Butyne−1, Butene−1, and Vinyl Acetylene, to the Normal Modes of Vibration of These Molecules

An attempt has been made to assign all the normal modes of vibration of the C4 hydrocarbons butyne−1, butene−1, and vinyl acetylene, in terms of frequencies observed in the infra-red and Raman spectra. It has been found to be possible to do this in a satisfactory manner which takes into account the structural similarities of these and other hydrocarbon molecules. With the help of these assignments previous data on the frequency ranges characteristic of the various hydrogen deformation modes of the groups ethyl, vinyl, and –C≡CH can be extended to include all such modes.