O=C(O[C@@H]1OC2COC(=O)c3cc(O)c(O)c(O)c3-c3c(cc(O)c(O)c3O)C(=O)O[C@H]([C@@H]2O)[C@H]1O)c1cc(O)c(O)c(O)c1
A higher negative pKa value denotes a less powerful acid. What is this molecule's negative pKa value?