COc1cc(/C=C2/C(=O)NN(c3ccc(C)c(Cl)c3)C2=O)cc([N+](=O)[O-])c1O
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?