Amine proton exchange

In amides, which are less basic than amines, proton exchange is slow, and coupling is often observed between the protons on nitrogen and those on the a carbon of an alkyl substituent that is substituted on the same nitrogen. 

Proton electrochemical gradient. 6,714 Proton exchange amine ligands, 2, 24 Proton loss catalysis... 

Gao, Y., Robertson, G. R, Guiver, M. D., Jian, X. G., Mikhailenko, S. D. and Kaliaguine, S. 2005. Proton exchange membranes based on sulfonated poly(phthalazinone ether ketone)s/aminated polymer blends. Solid State Ionics 176 409-415. 

The mechanism provides (in equation 1) a pathway for proton exchange in amine complexes. (In fact, it was the observation that proton exchange in [Co(NH3)6]3+313 and the base hydrolysis of (Co(NH3)5Br]2+298 had the same kinetic form that led Garrick to propose this mechanism in 1937.314) The pathway for base catalyzed solvolysis is made up of (1) + (2) + (3) and the pathway for base catalyzed substitution is (1) + (2) + (4). It was the observation of base catalyzed ligand substitution that provided the first strong evidence for the dissociative nature of the process.315... 

From the temperature dependence of the equilibrium constant for proton exchange between some deuterated and undeuterated primary and secondary amines, monitored by high-pressure mass spectrometry, the reaction enthalpy, or difference in proton affinity, could be measured.101 Protonation of the deuterated amine is favored by 0.2kcalmol-1, varying with structure by 0.1 kcal mol-1 but with no obvious pattern. However, the equilibrium, at least for CH3CD2NHCH3, appears to be entropy driven, not enthalpy. 

In contrast, the phosphino amide derivatives are isolated as air and moisture stable solids. Although they still have an aminic proton, the use of excess acetylacetonate does not produce further deprotonation. Their 31P NMR spectra suggest the presence of a rapid exchange equilibrium in solution, in which the remaining aminic hydrogen changes its position from one nitrogen to the other, even at low temperature [Eq. (21)]. 

H—C—N—H coupling in several amines was observed following rigorous removal (with Na-K alloy) of traces of water. This effectively stops proton exchange on the NMR time scale. [K.L. Henold, Chem. Commun., 1340(1970).]... 

Protons on the nitrogen atom of an amine salt exchange at a moderate rate they are seen as a broad peak, (<5 —8.5 to <5 -6.0), and they are coupled to protons on adjacent carbon atoms (/ 7 Hz). 

---