CC1=C(C(=O)Nc2ccc(Cl)cc2)C(c2ccccc2C)n2ncc(C(=O)Nc3ccc(C)cc3)c2N1
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?