Aldehydes and Ketones - Result Question 21
####21. The order of reactivity of phenyl magnesium bromide with the following compounds is
$(2004,1 M)$
(I)
(II)
(III) (a) (II) $>$ (III) $>$ (I)
(b) (I) $>$ (III) $>$ (II)
(c) (II) $>$ (I) $>$ (III)
(d) All of the above
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Answer:
Correct Answer: 21. (a)
Solution:
- The reactivity of carbonyl compound towards nucleophilic addition of Grignard’s reagent depends on extent of steric hindrance at $\alpha$-carbon. Greater the steric hindrance smaller the reactivity. Hence, reactivity order is
$\underset{\text { II }}{CH _3 CHO}>\underset{\text { I }}{CH _3-CO-CH _3}>Ph-\underset{\text { III }}{CO}-Ph$
