COc1cccc(CN2c3ccccc3-c3nc(SCC(=O)Nc4cccc(C)c4)ncc3S2(=O)=O)c1
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?