CCOc1ccc(N(CC)S(=O)(=O)N2CCCC(C(=O)Nc3cc(Cl)ccc3C)C2)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?