CCOc1ccc(NS(=O)(=O)c2ccc(Cl)c(NN=C3C(=O)NC(=S)NC3=O)c2)cc1Br
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?