O=C(CN1CCN(S(=O)(=O)c2cc(Cl)ccc2Cl)CC1)Nc1ccc2c(c1)OCCO2
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?