O=C(O)C(=O)O.O=C1CN(C(=O)CNCc2cccc(Cl)c2)c2ccccc2N1
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?