# Why isn't Indigo soluble in water?

Why isn't Indigo soluble in water? I mean, it has 2 H-N groups, shouldn't it then be able to hydrogen bond with water?

• Yes, and the lone pair of Nitrogen is interacting with $\pi$ system of the ring, so it diminished more the nucleophilicity(i am not sure if it is a correct word). Nice reasoning about the dipolar moment. It can be done "rigurously" by symmetry theory also. – user43021 Jun 5 '17 at 16:03