O=C1CCC[C@@H]2C[C@@]3(C[C@@H]4CCN1[C@@H]42)Nc1cc(Cl)c(Cl)cc1N=C3NCc1ccccc1
The negative base-10 logarithmic of dissociation constant (pka) for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the pKa value is directly proportional to the standard Gibbs free energy change for the reaction. What is the pka value of this molecule?