COc1cc(C2c3cc4c(cc3C(O[C@@H]3OC5COC(c6cccs6)OC5C(O)C3O)C3COC(=O)C23)OCO4)cc(OC)c1O
A lower number of negative pKa indicates that the acid dissociates more entirely in water. What is the negative pKa of this molecule?