COc1ccc(OC)c(CCNC(=O)c2cc3c(=O)oc4ccc(C)cc4c3s2)c1
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?