COc1ccc(NS(=O)(=O)c2ccc(N3CCOCC3)c(NC(=O)c3ccccc3Br)c2)cc1
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?