O=c1c2ccc(Cl)cc2oc2c(CNc3ccc(S(=O)(=O)Nc4nccs4)cc3)cccc12
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?