O=C(/C=C(\Nc1ccccc1O)c1ccc(Br)cc1)C(Cl)(Cl)Cl
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?