COC(=O)CN1C(=S)N(c2ccccc2)C(=O)C1CC(=O)Nc1ccc(Cl)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?