Vibrational analysis of 2-ethyl-1-butene and 3-pentanone

Infrared and Raman spectra were obtained for 2-ethyl-1-butene and infrared spectra were obtained for 3-pentanone. Normal coordinate calculations were made for all three possible conformers of each compound and the resulting vibrational assignments and force constants are given in this paper. Molecular mechanics and low-level ab initio molecular orbital calculations were also made for all the conformers. The results support the existence of three conformers of the alkene and two conformers of the ketone.