O=C(c1ccccc1)c1ccc2[nH]c(-c3c(Cl)c(Cl)c(Cl)c(Cl)c3C(=O)N/N=C/c3cccc(Oc4ccccc4)c3)nc2c1
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?