CBSE 2024 · Region 5 · Set 2 · Q28 · 3 marks
Account for the following : $\displaystyle \mathbf{1} \boldsymbol{\times} \mathbf{3}$(a)Haloalkanes react with NaCN to form both cyanides and isocyanides.(b)Haloarenes do not undergo nucleophilic substitution reaction easily.(c)Benzyl chloride gives $\displaystyle \mathrm{S}_{\mathrm{N}} 1$ reaction.
Account for the following : $\displaystyle \mathbf{1} \boldsymbol{\times} \mathbf{3}$
(a)
Haloalkanes react with NaCN to form both cyanides and isocyanides.
(b)
Haloarenes do not undergo nucleophilic substitution reaction easily.
(c)
Benzyl chloride gives $\displaystyle \mathrm{S}_{\mathrm{N}} 1$ reaction.
Marking-scheme solution
(a)
NaCN ionizes to give cyanide ion which is an ambidentate nucleophile, it can donate electrons either by using carbon or by using nitrogen.
(b)
Due to Resonance, a partial double bond is formedbetween \(\displaystyle \mathrm{C}-\mathrm{X} / \mathrm{sp}^{2}\) hybridization of carbon atom in C-X bond / Instability of phenyl cation.
(c)
Benzyl carbocation is resonance stabilized.
Haloalkanes and HaloarenesChemical Reactions of Haloalkanes and HaloarenesUnderstandshort_answermedium
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CBSE Class 12 Chemistry past-paper question from the 2024board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.