When Does A Proton Move?

The role of solvent in the proton transfer process is paramount and is illustrated by variation of equilibrium constant for the dissociation of HCl in water and acetonitrile differs by 17 orders of magnitude. A fundamental question that arises is: what determines the spontaneity of the proton transfer process? The available data suggest that the net electric field along the protic group serves as a descriptor for the spontaneous proton transfer process. The electric field experienced by an acid molecule depends on its local environment and a critical field is required for the spontaneous proton transfer process. In general, the fluctuations in solvent configuration leading to set of configurations that projects the electric field in excess of the critical electric field along the protic group, thus suggesting that the solvent electric field drives the proton-transfer process. 

References:

[1] M. Boda, G. Naresh Patwari, Phys. Chem. Chem. Phys. 19 (2017) 7461. 
[2] R.K. Singh, R. Pant, G.Naresh Patwari, J. Phys. Chem. B 126 (2022) 1590.