COc1ccc(-c2oc3cc(O[C@@H]4OC(CO)C(O)C(O)C4O)c(OC)c(O)c3c(=O)c2OC)cc1O
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?