O=C(CCN1C(=O)/C(=C\c2ccco2)SC1=S)Nc1ccc(C(=O)O)c(O)c1
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?