O=C1NC(=S)N(c2ccc(Cl)cc2)C(=O)/C1=C/N1CCN(C(=O)c2ccco2)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?