COc1ccc(C(=O)C(C(=O)CCC(=O)Nc2cccc(Cl)c2)c2ccc(OC)cc2)cc1
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?