COC(=O)c1ccc(OC(=O)C[S+]([O-])c2ccccc2[N+](=O)[O-])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?