Question

a. Which oxygen atom has the greater electron density?

b. Which compound has the greater electron density on its nitrogen atom?

c. Which compound has the greater electron density on its oxygen atom?

Short answer

a) The carbonyl oxygen has greater electron density.

b) The compound on the right has the greater electron density on it nitrogen because the compound on the left has a resonance contributor with positive charge on nitrogen atom as a result of electron delocalization.

c) The compound with the cyclohexane ring has the greater electron density on its oxygen because the lone pair on the nitrogen can be delocalized only on to the oxygen.

Step-by-step solution

Resonance structures

a)

b)

c) 1

2.

Final answer

a) The carbonyl oxygen has greater electron density.

b) The compound on the right has the greater electron density on it nitrogen because the compound on the left has a resonance contributor with positive charge on nitrogen atom as a result of electron delocalization.

c) The compound with the cyclohexane ring has the greater electron density on its oxygen because the lone pair on the nitrogen can be delocalized only on to the oxygen.

There is less delocalisation onto oxygen by the lone pair in the compound with the benzene ring because the lone pair can also be delocalized away from the oxygen into the benzene ring.