O=C(N/C(=C/C=C/c1ccccc1)C(=O)N1CCOCC1)c1ccccc1Br
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?