COc1cc(C(=O)NNC2=NC(C)(C)Cc3cc(C)c(C)cc32)cc(OC)c1OC
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?