O=C1CC(=O)NC(NN2C(=O)/C(=C/c3ccc(Cl)cc3)N=C2c2ccccc2)=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?