a) Treatment of compound D with 1-hexylamine resulted in the exclusive displacement of the chloro group at position 7 to give the product E. Explain why reaction did not also occur at position 3 to displace the Bromo group in an analogous process. 

b) Three of the four nitrogens atoms of E are basic but the fourth is not protonated, even under very acidic conditions. Identify this non-basic nitrogen and explain why it is unreactive. 

NH2 heat D. Br E Br