O=C(CSc1nc[nH]n1)N1N=C(c2ccc(Cl)cc2)CC1c1ccco1
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?