COc1ccc(CNC(=O)COc2cc3c(c4oc(=O)cc(C)c24)CCC(C)(C)O3)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?