Proton transfer, hydrogen bonds mechanisms

ApA < 1. In Fig. 2 the region of curvature is much broader and extends beyond — 4 < ApA < + 4. One explanation for the poor agreement between the predictions in Fig. 3 and the behaviour observed for ionisation of acetic acid is that in the region around ApA = 0, the proton-transfer step in mechanism (8) is kinetically significant. In order to test this hypothesis and attempt to fit (9) and (10) to experimental data, it is necessary to assume values for the rate coefficients for the formation and breakdown of the hydrogen-bonded complexes in mechanism (8) and to propose a suitable relationship between the rate coefficients of the proton-transfer step and the equilibrium constant for the reaction. There are various ways in which the latter can be achieved. Experimental data for proton-transfer reactions are usually fitted quite well by the Bronsted relation (17). In (17), GB is a... 

The presence of water in PVPA seems to contribute to the conductivity of PVPA, at a temperature below the boiling point of water, by proton transport in additional proton solvents. Hence, the proton movement in PVPA can be explained by rapid transfer of protons via hydrogen bond-forming and bondbreaking (hopping mechanism) and by self-diffusion (vehicle mechanism). Different conductivity values could be obtained due to a different water content. Also, recent studies have revealed that the behavior of PVPA as a polyelectrolyte is very similar to poly(actylic acid) in aqueous salt solution under identical conditions. ... 

Keywords l-Ethyl-3-methyliinidazoliuin acetate Acid-base equilibria Basic ionic liquids Carbene Catalysis CO2 capture DFT calculations Hydrogen bonding Ionic liquids Mass spectroscopy N-Heterocyclic carbenes Organocatalysis Photoelectron spectroscopy Proton transfer Synthesis Vaporization mechanism... 

The last reaction occurs so promptly that the diffusion-express mechanism is proposed for it where the proton transfer occurs due to the displacement of protons along hydrogen bonds... 

When the acids HA and BH are of similar acidity (ApAT ca 0) the interpretation of the kinetic behaviour is less straightforward. It is usual to interpret the reaction by the mechanism in (8). The intermediates Ix and I2 are assumed to be hydrogen-bonded complexes, so that the proton-transfer step... 

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