O=C(NCCN1CCCC1)c1ccc2c(c1)N(Cc1cccc(Cl)c1)C(=O)c1ccccc1S2(=O)=O
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?