Ketones infrared absorption frequencies

Aldehydes Amides Carboxylic acid anhydrides Carboxylic acids Esters Ketones and functional groups, 56 infrared absorption frequencies, 519,... 

Table 48. Infrared carbonyl stretching absorption frequencies of cyclic ketones ) ...

Figure 4 illustrates the infrared spectrum for a sample of PPE. The absorptions of the peaks at 3.4, 6.9 and 7.3 pm were assigned to C-H stretch and C-H bending frequencies in CH2 and CH3 (33). These absorptions are proportional to the surface density of deposited ethane (16). However, the absorptions at photons near 10 pm are attributable to OH deformations and CO stretchings of alcoholic groups and vibrations of alkyl ketones (22). They also indicate the existence of branches in unsaturated chain (33). 

Different types of carbonyl groups give characteristic strong absorptions at different positions in the infrared spectrum. As a result, infrared spectroscopy is often the best method to detect and differentiate these carboxylic acid derivatives. Table 21-3 summarizes the characteristic IR absorptions of carbonyl functional groups. As in Chapter 12, we are using about 1710 cm-1 for simple ketones and acids as a standard for comparison. Appendix 2 gives a more complete table of characteristic IR frequencies. 

Norlutin and Enovid are ketones that suppress ovulation. Consequently, they have been used clinically as contraceptives. For which of these compounds would you expect the infrared carbonyl absorption (C = 0 stretch) to be at a higher frequency Explain. 

The Infrared spectra of these compounds show the characteristic carbonyl frequency of absorption expected for hydrogen bonded enamine ketones. 

Infrared Analysis, The spectrum (Fig. 6.8 p. 160) of the ketone was discussed in Experiment [5B].The major change observed in the spectrum of the product (Fig. 6.32), when compared with the starting material, is the loss of the carbonyl absorption band (1717 cm ), and its replacement by a less-intense new band at 1654 cm. This latter absorption is associated with the stretching motion of the C=C system exocycUc to the six-membered ring. The key bands associated with group frequencies present in the reaction product are identihed at 3075, 3000-2850, 1783, 1654, 1394,1368, and 883 cm ... 

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