COc1ccc2c(c1)C(=O)[C@@H](O)[C@H](c1ccc(OC)c(Br)c1)O2
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?