O=c1c2cc(N3CCOCC3)ccc2[nH]c(=S)n1CCCN1CCCC1
An acid's negative base-10 logarithmic dissociation constant (pKa) follows directly from its underlying thermodynamics; the negative pKa is directly proportional to its standard Gibbs free energy change. What is the negative pKa value of this molecule?