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Question
Which of the compounds will react faster in SN1 reaction with the –OH ion?
\[\ce{CH3-CH2-Cl}\] or \[\ce{C6H5-CH2-Cl}\]
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Solution
\[\ce{C6H5-CH2-Cl}\]
SN1 reaction proceeds through the formation of carbonation intermediate.
\[\ce{C6H5CH2Cl}\] readily undergoes ionization to give \[\ce{C6H5CH^{+}2}\] carbocation, which is stabilized by resonance.
On the other hand, \[\ce{CH3CH2Cl}\] does not undergo ionization to give \[\ce{CH3CH^{+}2}\] carbonation. Therefore, \[\ce{C6H5CH2Cl}\] reacts faster than \[\ce{CH3CH2Cl}\] with \[\ce{OH-}\] ion.
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| (ii) | \[\begin{array}{cc} \ce{CH3 - CH = CH2 + HBr -> CH3 - CH - CH3}\\ \phantom{............................}|\phantom{}\\ \phantom{.............................}\ce{Br}\phantom{} \end{array}\] |
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| (iii) |  |
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| (iv) |  |
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| (v) | \[\begin{array}{cc} \ce{CH3 CH2 CH CH3 ->[alc.KOH] CH3 CH = CH CH3}\\ \phantom{}|\phantom{..........................}\\ \phantom{}\ce{Br}\phantom{........................} \end{array}\] |
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