O=c1c2cc(NC(=S)N3CCC(N4CCCCC4)CC3)ccc2nc2n1CCCCC2
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?