O=C(NC1CCCC1)c1cccc2c1C(=O)c1ccc(/C=C/c3ccccc3)cc1S2(=O)=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?