C[C@@H]1O[C@@H](OC2C(O)C(OCCc3ccc(O)c(O)c3)OC(CO)C2OC(=O)/C=C/c2ccc(O)c(O)c2)[C@H](O)[C@H](O)[C@H]1O
A higher negative pKa value denotes a less powerful acid. What is this molecule's negative pKa value?