NS(=O)(=O)c1ccc(NC(=O)COC(=O)c2ncc(Cl)c(Cl)c2Cl)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?