(a) Write two important differences between inductive and resonance effects.

(b) Give reasons to explain the following observations:


(i) Carbon number ‘2’ in CH3CH2Cl has more positive charge than that in CH3CH2Br.


(ii) CH3–CH = CH–CH = CH2 (I) is more stable than CH3–CH = CH–CH2–CH = CH2 (II).



(a)



(b)


(i) Carbon number ‘2’ in CH3CH2Cl has more positive charge than that in CH3CH2Br because Cl is more electronegative than Br and that’s why C-Cl bond is more polar than C-Br bond. Cl keeps the shared electron pair towards itself as it is more electronegative. So the carbon adjacent to Cl acquires more positive charge s compared to carbon adjacent to Br.


(ii) CH3–CH = CH–CH = CH2 (I) is more stable than


CH3–CH = CH–CH2–CH = CH2 (II) because I shows resonance effect whereas there is no conjugation in II. We already know that more the resonating structure more is the stability. I have 2 resonating structures and thus, it is more stable.


CH3–CH = CH–CH = CH2 CH3=CH - CH=CH - CH2


1
1