COc1ccccc1NS(=O)(=O)c1cc(NC(=O)c2cc(O)nc3ccccc23)ccc1N1CCOCC1
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?