COC(=O)COc1c(Cl)cc(C(c2c(C)n[nH]c2O)c2c(C)n[nH]c2O)cc1OC
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?