C=C(C)COc1ccc(-c2nc(N)ncc2-c2ccc(Cl)cc2)c(O)c1
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?