COc1cc(S(=O)(=O)N/N=C/c2cc(Br)c(O)c(OC)c2)c(OC)cc1NC(C)=O
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?