O=C1OC2(c3cc(Br)c(O)c(Br)c3Oc3c2cc(Br)c(O)c3Br)c2c(Cl)c(Cl)c(Cl)c(Cl)c21
A lower number of negative pKa indicates that the acid dissociates more entirely in water. What is the negative pKa of this molecule?