Draw the structure of a carbonyl group and indicate clearly:
i) the hybridised state of carbon
ii) the σ and π bonds present
iii) the electrophilic and nucleophilic centres in it
i) the hybridised state of carbon
ii) the σ and π bonds present
iii) the electrophilic and nucleophilic centres in it
Answer: C is sp²; C=O = one σ + one π; C is the electrophilic centre (δ+), O the nucleophilic centre (δ−).
Solution
The carbonyl, C=O, is planar:
(i) carbon is \textbf{sp}-hybridised (bond angles ≈120°).
(ii) C=O consists of one σ (sp–p overlap) and one π bond (p–p); the two remaining sp orbitals form σ bonds to the substituents.
(iii) Oxygen's greater electronegativity polarises the bond C=O: the \textbf{carbon is the electrophilic centre} (attacked by nucleophiles), the \textbf{oxygen the nucleophilic centre} (attacked by electrophiles/protons).
(i) carbon is \textbf{sp}-hybridised (bond angles ≈120°).
(ii) C=O consists of one σ (sp–p overlap) and one π bond (p–p); the two remaining sp orbitals form σ bonds to the substituents.
(iii) Oxygen's greater electronegativity polarises the bond C=O: the \textbf{carbon is the electrophilic centre} (attacked by nucleophiles), the \textbf{oxygen the nucleophilic centre} (attacked by electrophiles/protons).
CBSE Class 12 Board · 2004 · Delhi · Subjective