COc1cc(C2C3=C(COC3=O)OC(C)(C)Oc3cc4c(cc32)OCO4)cc(OC)c1O
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?