CCn1ncc(C2=NOC(C(=O)Nc3cc(OC)c(Cl)cc3OC)C2)c1C
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?