COc1ccc(C(=O)c2oc3ccccc3c2NC(=O)c2cc(=O)c3ccc(C)cc3o2)cc1Cl
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?