NCERT Class XI Chemistry Organic Chemistry Some basic principles and Techniques Solutions
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Question : 11
Total: 40
Draw the resonance structures for the following compounds. Show the electron shift using curved-arrow notation.
(a)C 6 H 5 O H
(b)C 6 H 5 N O 2
(c)C H 3 C H = C H C H O
(d)C 6 H 5 – C H O
(e)C 6 H 5 − C + H 2
(f)C H 3 C H = C H C + H 2
(a)
(b)
(c)
(d)
(e)
(f)
Solution:
(a) Resonance structures of phenol are
Phenol is a planar molecule. The p-orbitals on each carbon atom lie perpendicular to the plane of the molecule, the oxygen atom lying in its p-orbital is also perpendicular to the molecule. Consequently the p-orbital overlap, between O and C takes place and the resonance structures arise.
(b)– N O 2
(c)C H 3 C H = C H C H O
(d) Oxygen being highly electronegative pulls the π-electron cloud of the C=O towards itself thereby leaving the carbonyl carbon with a positive charge. In order to compensate this electron deficiency, the electron cloud from the ring moves towards it and the resonance structures arise.
Phenol is a planar molecule. The p-orbitals on each carbon atom lie perpendicular to the plane of the molecule, the oxygen atom lying in its p-orbital is also perpendicular to the molecule. Consequently the p-orbital overlap, between O and C takes place and the resonance structures arise.
(b)
(c)
(d) Oxygen being highly electronegative pulls the π-electron cloud of the C=O towards itself thereby leaving the carbonyl carbon with a positive charge. In order to compensate this electron deficiency, the electron cloud from the ring moves towards it and the resonance structures arise.
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