The study of the spectra of thirty-six aliphatic ketones in the seven to ten micron region has led to the recognition of bands which permit the facile differentiation of ketones of the three following types. CH3COCH2R, CH3CH2COCH2R, and RCH2CH2COCH2CH2R. The differentiation is based upon the fact that the spectra of methyl ketones show bands at 7.38 and 8 60 microns, while those of ethyl ketones have a characteristic band at 9 03 microns The 9 03 micron band in the spectra of ethyl ketones is in addition to bands at 8.60 and 8 82 microns, which are present also in the spectra of ketones of the type RCH2CH2COCH2CH2R (R≠H).
M. A. Gianturco and R. G. Pitcher, "New Spectra-Structure Correlations of Aliphatic Ketones," Appl. Spectrosc. 19, 109-110 (1965)