Group Absorptions

Functional Group Absorption (cm ) Intensity Functional Group Absorption cm 1) Intensity... 

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... 

The technologies currently available for post-combustion capture are classified into five main groups absorption, adsorption, cryogenics, membranes and biological separation. The most mature and closest to market technology and so, the representative of first generation of postcombustion options, is capture absorption from amines. 

Type of Compound Infrared Absorption due to Following Functional Groups Absorption Range (cm-1) Mass Spectra m/z Signal... 

Table 14.1 Characteristic group Absorptions in IR spectra of organic molecules.

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.

Characterization of the donor bound polymers follows from their spectroscopic (ir and uv-vis KBr) properties in comparison with the starting donor monomers, and from elemental analyses. That the donors are covalently bound to the polymer and not present as unreacted monomers can be seen by the absence of the characteristic monomer functional group absorption (i.e. -OH, COzH) in the donor bound polymer. For example in Figure 1, the comparative ir spectra of p-hydroxyphenyl-TTF monomer and this donor covalently bound to linear and to cross-linked polysytrene are given. Except for the presence of the hydroxyl absorption in the monomer, all three spectra are essentially identical, indicating a rather clean polymer attachment reaction. 

The proton NMR of the distillate shows the two methyl group absorptions of (trifluoromethyl)trimethylsilane and chlorotrimethylsilane in a ratio of about 85 15. The material solidifies in a dry ice-acetone cooled trap. 

The final example Involves the alkenyl hydrocarbons, a class whose distinguishing group absorptions are only subtly different from those of other hydrocarbons. Figure 5 shows the projection of alkenyl and aryl hydrocarbons onto the second and third eigenvectors. Better separation occurs In this case than could be obtained for the chloro compounds shown In Figure 4 using the third and fourth eigenvectors. Thus, It may be expected that the alkenyl... 

Notably, starting and intermediate nitriles used in the synthesis of 2-amino-3-cyanopyrans show moderate to weak nitrile group absorption at 2260-2220 cm, the nitrile band is very characteristic. 

Co(II) in a chelate complex (A) was studied and observed by the NMR method [70]. The band of a proton of hydroxyl group absorption was observed to change the frequency of absorption and the height of the peak after addition of the solvent (CC14 + CH2C12) to complex... 

This section is concerned with a comprehensive look at these characteristic group absorptions and their relationship to molecular structure. As a major type or class of molecule or functional group is introduced in the succeeding sections, an example of an IR spectrum with the important peak assignments will be given. Spectra of common laboratory substances, representing... 

C—H Stretching Vibrations Tertiary C—H Groups Absorption resulting from this vibrational mode is very weak and is usually lost in other aliphatic C—H absorption. Absorption in hydrocarbons occurs near 2890 cm-1. 

Assignments for C—H out-of-plane bending bands in the spectra of substituted benzenes appear in the chart of characteristic group absorptions (Appendix C). These assignments are usually reliable for alkyl-substituted benzenes, but caution must be observed in the interpretation of spectra when polar groups are attached directly to the ring, for example, in nitroben-zenes, aromatic acids, and esters or amides of aromatic acids. 

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