CCOc1cc(C2c3c(oc4ccccc4c3=O)C(=O)N2Cc2ccccc2Cl)ccc1O
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?