C[C@]12CC[C@H]3[C@@H](CCC4=C/C(=N/O)CC[C@@]43C)[C@@H]1CC(=C\c1cccnc1)/C2=N\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?