COc1cc(OC)c(NC(=O)C2CCN(S(=O)(=O)c3ccc4c(c3)oc(=O)n4C)CC2)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?