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Chemistry · 2025 · 3 marks
CBSE 2025 · Region 5 · Set 1 · Q25
Account for the following: (a) The C - Cl bond length in chlorobenzene is shorter than that in methyl chloride. (b) Grignard reagents should be…
Account for the following :
(a)
The C - Cl bond length in chlorobenzene is shorter than that in methyl chloride.
(b)
Grignard reagents should be prepared under anhydrous conditions.
(c)
In case of optically active alkyl halides, $\displaystyle \mathrm{S}_{\mathrm{N}} 1$ reactions are accompanied by racemisation.
Marking-scheme solution
(a)
Due to resonance in chlorobenzene leading to partial double bond character of C-Cl bond but
there is no resonance in CH3Cl / sp2 hybridised carbon atom having shorter bond length
between C-Cl in chlorobenzene than sp3 hybridized carbon in methyl chloride.
(b)
Grignard reagent react with water to form corresponding hydrocarbon
(c)
Due to the formation of planar carbocation, nucleophile may attack from either side of
carbocation.
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