CCOC(=O)C1=C(Nc2ccccc2)S/C(=C\c2ccc(OCC(=O)O)c(OCC)c2)C1=O
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?