Carbonyl group absorptions

Figure 3. Formation of carbonyl group absorption at 1714 cm in polypropylene samples exposed to ozone and UV light (L2).

In the mass spectra of all these substances (4,5,14,15,87,92,94), the molecular ions peaks are present. The base peak at m/z 58, typical for all the seco alkaloids with the N,iV-dimethylaminoethyl chain, corresponding to the CH2=N(CH3)2+ ion is observed. The main mass fragmentation under electron impact seems to involve bond cleavage between C-l and C-9. This can be evidenced by the presence of ions of the 122 and 123 type found in spectra of all compounds except for N-methylhydrastines (98, 99), where the 123 — C02 ion is formed instead. Finally, the carbonyl group absorption... 

Figure 8.33 Strong, sharp band at 1700 cnY1 indicating a carbonyl group. Absorption bands on the high side of 3000 cnY1 and a series of weak bands between 1700 and 2000 cnY1 indicating a benzene ring. Possibly benzaldehyde, or a similar compound.

Scheme 3.5 Resonance showing strong carbonyl group absorption when X is strongly electronegative...

C c PO (10 mmol), BrTBDPEG150TBDBr (0.5 mmol), C02 (3 MPa), 120 °C, 1749 cm 1 corresponds to peak for carbonyl group of carbamic acid formed between C02 and BrTBDPEG150TBDBr. 1790 cm-1 was the carbonyl group absorption of the product PC. Reproduced from Ref. [15] by permission of The Royal Society of Chemistry... 

The main spectroscopic characteristics of the coupled anthracenonic compounds are the following in visible UV spectra, there is a weak maximum between 410 and 420 nm and intense absorption in the region of 220-270 nm in IR, all isolated compounds show a strong absorption band at 3390 cm1, due to hydroxyl groups, and a chelated carbonyl group absorption at 1600-1635 cm1. Mass spectra show the loss of one or two molecules of H2O and a prominent ion representing the monomeric subunits. HNMR spectra reveal the presence of three or four chelated... 

We also studied the interaction of the ATG isocyanate groups with the MMA double bonds. In this csise substituted amide groups must be formed that can act as crosslinks in the branching of the polymer chain — N — CO —. A weak band of carbonyl group absorption... 

The influence of the stracture of the benzoyl peroxide symmetrical derivatives (R-PhC (O)-O-O-C (O) Ph-R) on the position of the carbonyl groups absorption band in the IR spectra has been also investigated. Calculations were carried out in the approximation of AMI, PM6 and PDDG semiempirical methods. The best correspondence between the experimental and calculated parameters is observed in the case of PM6 method (Table 11.2). Introduction of electron-donor substituents into... 

From the molecular formula and the IR spectrum, we learn that the compound is a ketone it has a carbonyl group at 1680 cm only one oxygen, and no absorption bands at 2820 and 2720 cm that would indicate an aldehyde. The carbonyl group absorption band is at a lower frequency than is typical, which suggests that it has partial single-bond character as a result of electron delocalization, indicating that it is attached to an sp carbon. Now we can conclude that the compound is the ketone shown here. The integration ratio (5 2 3) confirms this answer. 

The rate of polymerization of racemic PEL was determined in two different solvents, tetrahydrofuran (THE) and dimethyl sulfoxide (DMSO), at two different temperatures with tetraethylammonium benzoate as initiator, and the results are collected in Table III, The reactions were followed by infrared spectroscopy based upon the carbonyl group absorption intensities for the monomer and polymer, and the data was treated according to the following pseudo-first order rate equation ... 

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