Exchange hydrogenic atoms

Corrected for the different number of exchangeable hydrogen atoms. 

Fig. 4. Helical structure of collagen, typical amino acid sequence within a collagen strand, and exchangeable versus non-exchangeable hydrogen atoms in an individual leucine molecule (Gly - glycine. Pro - Proline, Leu - leucine. Hyp - hydroxyproline.

The products of reductive cyclization incorporate two non-exchangeable hydrogen atoms. Homolytic and heterolytic hydrogen activation pathways may now be discriminated on the basis of hydrogen-deuterium crossover experiments. Reductive cyclization of the indicated nitrogen-tethered enyne under a mixed atmosphere... 

Figure 16 shows that the reaction coordinate for exchange involves two zeolite oxygen atoms, one which acts as a proton donor (acid) and the other as a proton acceptor (base). Both exchangeable hydrogen atoms lie approximately halfway between the carbon atom and their respective oxygens. Comparison of literature geometries indicates that the precise... 

Fig. 6. Average number of exchanged hydrogen atoms per molecule in the coisomerization ol ra-2-butene-d0 and n s-2-butene-ds (1 1) on MoS2 in the presence of a mixture of H2 and D2 (1 1) at room temperature (6).

Exchange of Cyclopropanes in Liquid Ammonia-Potassium Amide [Number of Exchanged Hydrogen Atoms (n.)]... 

These hydrocarbons are generated from the Raney nickel reduction of the sulfides, and the most abundant member of the sulfides is also the C23 compound. Finally, three deuterium-exchangeable hydrogen atoms were observed for the sulfone derivative of the C23 sulfide, Figure 11. The structure established for the C40 member of the series is ... 

One of the major difficulties in obtaining NMR spectra of imidazoles is a consequence of their low solubility in most suitable solvents except for water. This may often lead to incomplete, or ill-defined, spectra, particularly where there are a number of exchangeable hydrogen atoms, e.g., in polyhydroxyalkyl-substituted imidazoles. Some imidazoles, for instance, 1-methyl- and 2-acetyl-4-methylimida-zole are readily soluble in deuteriochloroform, while deuteriated pyridine, acetone, or dimethyl sulfoxide may prove useful in other cases. Reddy et ai.220 have suggested conversion of imidazoles into their N-acetyl derivatives which are soluble either in deuteriochloroform or in a mixture of deuteriochloroform and dimethyl sulfoxide. Although, as mentioned above, in neutral organic solvents the 4- and... 

Acids are related to their anions by exchanging hydrogen atoms of the acids for the same number of negative charges on the anions. For example. 

Denterinm magnetic resonance spectroscopy has fonnd wider applications since the advent of highly sensitive Fonrier transform spectrometers. Denterinm is preferred choice in molecnlar and in H NMR spectroscopy in order to provide additional information abont proton vibrations and resonances spectra measnred before and after denteration help to locate the exchanging hydrogen atoms. 

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