COc1ccc(C)cc1NC(=O)CSc1ncc2c(n1)-c1ccc(Cl)cc1N(Cc1ccccc1)S2(=O)=O
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?