COc1ccc(Cl)cc1-n1c(=S)sc2c(O)nc(SCC(=O)NCCC(C)C)nc21
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?