COc1ccccc1-c1c[nH]c(C(O)c2ccc(Cl)c(Cl)c2)n1
The negative base-10 logarithmic of dissociation constant (pka) for an acid is a direct consequence of the underlying thermodynamics of the dissociation reaction; the pKa value is directly proportional to the standard Gibbs free energy change for the reaction. What is the pka value of this molecule?