Answer to Question #57779 in Organic Chemistry for tracy ng
Why is quercetin insoluble in water?
This is due to pi stacking interaction between molecules quercetin.
Between the molecules of quercetin occur aromatic interaction (or π-π interaction). π-π interactions are caused by intermolecular overlapping p-orbitals in the π-conjugated systems, so that they become stronger as the number of π-electrons increases.
In other words, the polar substituents of one molecule of quercetin hang over the aromatic ring of the neighboring molecule. As a result of this interaction quercetin molecule hydroxyl groups are not capable of dissociating. This causes that quercetin is not soluble in water.