O=C(COC(=O)Cn1cc(C(F)(F)F)ccc1=O)Nc1ccc(Br)cc1F
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?