Carbonyl group Raman frequencies

The IR and Raman spectra of esters derived from peroxycarboxylic and peroxycarbonic esters show a band near 860 cm-1, assigned to a stretching mode of the 00 group. The band of the carbonyl group in these compounds is shifted to higher frequencies by 30-40 cm-1, as compared to ordinary esters567. 

The carbonyl group exhibits a very strong IR band and a medium to strong Raman band in the region between 1850 and 1650 cm. Table 4.1-6 shows the position of the carbonyl frequency under the constraints of mesomeric, inductive, and geometric effects as well as dynamical interactions. A number of simultaneously present bands helps to characterize the nature of the C=0 group ... 

Hydantoins show two bands in the carbonyl region at about 1720 and 1780 cm-1. However, their interpretation has been the subject of controversy. The low-frequency band has been attributed both to the C-4168 and the C-2 carbonyl group.169 Infrared and Raman spectra have also been interpreted in terms of carbonyl coupling similar to that found in imides.170 Other studies have confirmed this coupling.171... 

Q What would be the wavelength of the Raman band corresponding to a carbonyl group frequency of 1650 cm , assuming a laser wavelength of 546.0 nm ... 

Physical Properties.—In a comparative study of the i.r. and Raman spectra of oxazolidine- (322 X = O), thiazolidine- (322 X = S) and selenazo-lidine-2,4-diones (322 X = Se), the observations are interpreted in terms of coupling between the carbonyl groups, identical to that shown by cyclic imides such as hydantoins (323), The carbonyl band of low frequency... 

Similarity between these IR and Raman spectra and those of other polyesters, such as PET, PBT, etc., are expected. Also, the presence of the bisphenol A and paradisubstituted aromatic ring components have a close similarity to those of Lexan (a polycarbonate). Consequently, the IR and Raman spectra are expected to be close in appearance to those of Lexan, although the frequency of the carbonyl group is expected to be different. The similarities can be appreciated by comparing the spectra from these materials Fig. 49 with those of Lexan (Reference Spectrum 28). 

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