Functional Groups Containing Carbon

Carbon-13 NMR spectrometry permits direct observation of carbon-containing functional groups the shift ranges for these are given in Appendix A. With the exception of CH=0, the presence of these groups could not be directly ascertained by H NMR. 

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Several functional groups containing carbon-nitrogen double bonds can participate in radical cyclizations. Among these are oxime ethers, imines, and hydrazones.337 Hydrazones and oximes are somewhat more reactive than imines, evidently because the adjacent substituents can stabilize the radical center at nitrogen.338 Cyclization at these functional groups leads to amino- substituted products. 

Carbon-13 NMR spectroscopy allows the direct observation of carbon skeletons of dyestuffs including functional groups containing carbon atoms (e.g. 

Methane and compounds whose major functional group contains only carbon-carbon single bonds are alkanes. Carbons in alkanes are referred to as methyl, primary, secondary, and tertiary, depending upon how many other alkyl groups are attached to them. Methyl carbons have no attached alkyl groups, primary carbons have one, secondary have two, and tertiary have tliree. 

FTIR and NMR Analysis of Oxidation Products. As expected the FTIR spectra of the soluble oxidation products are dominated by the strong absorptions due to the hydroxyl and carbonyl groups of carboxylic acids. There are absorptions in the spectra which occur in the regions expected for sulfones (1350-1310 and 1160-1120 cm-1) and sulfonic acids (1420-1330 and 1200-1145 cm-1), but these are probably due to non-sulfur containing functional groups, especially carbon-oxygen bonds which are presumably present in much higher concentrations. 

FIGURE 5.3 Examples of nitrogen-containing surface functional groups in carbons (1) pyridine-type N, (2) pyrrole-type N, (3) basal-plane N (edge), (4) amine-type N, (5) substitutional N, and (6) quaternary N. (The top layer shown represents the graphene edge.)... 

Phenol groups are determined by the difference of the neutralization reactions between sodium hydroxide and sodium carbonate which are common for carboxylic and phenolate groups. Oxidized carbons (typically in air at 700 K) contain equal amounts of these two functional groups. Activated carbons contain up to 800/zeqg-1 carbon of phenolate groups. The volumetric determinations are also sensitive to both carboxylic and phenolate groups so that specific deri-vatization processes are needed to reliably discriminate the two types of groups. 

The chemical shifts of those signals suggest what types of functional groups contain those carbon atoms. 

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