O=C1CC(N(C(=O)c2ccco2)c2cccc(Cl)c2)C(=O)N1c1cccc(Cl)c1
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?