O=C(CN1C(=O)C(=O)N(Cc2ccccc2)C1=O)Nc1cc(Cl)cc(Cl)c1
An acid's negative base-10 logarithmic dissociation constant (pka) follows directly from its underlying thermodynamics; pKa is directly proportional to its standard Gibbs free energy change. What is the pka value of this molecule?