O=C(NC(C(=O)c1ccccc1)n1c(=O)cc[nH]c1=S)c1ccccc1
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?