O=C(CN1C(=O)c2ccccc2C1=O)OC(C(=O)c1ccc(Cl)cc1)c1ccccc1
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?