O=C1[C@H]2O[C@@H]2[C@@H](O)[C@H]2[C@H]1CCn1c(=O)n(Cc3cc4c(cc3Cl)OCO4)c(=O)n12
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?