O=C(Nc1cc(S(=O)(=O)N2CCOCC2)ccc1Cl)C(=O)c1c(-c2ccccc2)cc2ccccn12
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?