Vibration spectra of hydrocarbon molecules - II. Skeletal frequencies in certain branched paraffins

摘要: Saturated paraffins containing the terminal grouping (CH$\_{3}$)$\_{3}$ C$\ldots $ show strong absorption bands in infra-red at 1250 and 1200 cm.$^{-1}$, while those (CH$\_{3}$)$\_{2}$ CH$\ldots 1170 1145 cm.$^{-1}$. It has been shown that these other characteristic frequencies should be assigned as vibrations of carbon skeleton structural units. Further, by using a simple valency force field on model molecules X$\_{3}$YZ X$\_{2}$WZ (where X is CH$_{3}$ group, Y atom, W CH Z large mass representing remainder molecule), satisfactory agreement between observed calculated obtained. The implications results more general problem interpretation vibration spectra hydrocarbons considered. In particular, it emphasized such skeletal are least partly responsible for intense complex branched paraffins, which stress hitherto placed mainly role hydrogen atoms.