(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