CCOC(=O)C1=C(Nc2ccc(C)cc2)S/C(=C\c2ccc(-c3ccccc3C(=O)O)o2)C1=O
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?