An SN1 reaction occurs through the formation of a carbocation intermediate. Alkyl halide (I) is tertiary (3°), whereas (II) is secondary (2°). As a result, (I) forms a tertiary carbocation, while (II) forms a secondary carbocation. Since the rate of an SN1 reaction increases with carbocation stability, and a tertiary carbocation is more stable than a secondary carbocation, compound (I), i.e., 2-chloro-2-methylpropane, undergoes the SN1 reaction faster than compound (II), i.e., 3-chloropentane.
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प्रश्न
In the following pair of halogen compounds, which compound undergoes a faster SN1 reaction?
In the following pair of halogen compounds, which compound undergoes SN1 reaction faster and why?
लघु उत्तर
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उत्तर १
The activity of halogen compounds in SN1 reaction depends on the stability of the carbocation formed due to ionization. The order of stability is tertiary > secondary > primary. Hence, 3° alkyl chloride is more active than 2° alkyl chloride. Hence,3° alkyl chloride is more active in the SN1 reaction.
The compound which react faster is:
The carbocation, which will be more stable and responsible for the faster reaction, is:
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उत्तर २
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Notes
Students should refer to the answer according to their questions.
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पाठ 6: Haloalkanes and Haloarenes - Intext Question [पृष्ठ १८६]
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| (I) |  |
| (II) |  |
| (III) |  |
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\[\begin{array}{cc}
\ce{CH3CHCH2CH2Br}\\
|\phantom{.............}\\
\ce{CH3}\phantom{..........}\\
\end{array}\] or \[\begin{array}{cc}
\ce{CH3CH2CHCH2Br}\\
|\\
\phantom{...}\ce{CH3}\\
\end{array}\]
