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When 3-methylbutan-2-ol is treated with ...

When 3-methylbutan-2-ol is treated with HBr, the following reaction takes place:
`CH_(3)-underset(CH_(3))underset("| ")("C ")H-underset(OH)underset("| ")("C")H-CH_(3)overset(HBr)rarr CH_(3)-overset(Br)overset("| ")underset(CH_(3))underset("| ")("C ")-CH_(2)-CH_(3)`
Give a mechanism for this reaction.
(Hint : The secondary carbocation formed in step II rearranges to a more stable tertiary carbocation by a hydride ion shift from 3rd carbon atom.

Text Solution

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Protonation of the given alcohol followed by loss of water gives a `2^(@)` carbocation (I), which being unstable rearranges by 1,2-hydride shift to form the more stable `3^(@)` carbocation (II). Nucleophilic attack by Br ion on this carbocation (II) gives the final product.
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When 3 - methylbutan -2- ol is treated with HBr , the following reaction takes place : CH_(3)-underset(CH_(3))underset("| ")"CH"-underset(OH)underset("| ")"CH"-CH_(3)overset(HBr)rarrCH_(3)-overset("Br")overset("| ")underset(CH_(3))underset("| ")"C "-CH_(2)-CH_(3) Give a mechanism for this reaction.

When 3-methylbutane-2-ol is treated with HBr, the following reaction takes place: CH_(3)-underset(CH_(3))underset(|)(C)H-underset(OH)underset(|)(C)H-CH_(3) overset(HB r)to CH_(3)-underset(CH_(3))underset(|)overset(Br)overset(|)(C)-CH_(2)-CH_(3) Give a mechanism for this reaction.

Knowledge Check

  • The IUPAC name of CH_(3)-underset(OH)underset("| ")"CH"-CH_(2)-overset(CH_(3))overset("| ")underset(OH)underset("| ")"C "-CH_(3) is :

    A
    1, 1 - dimethyl -1, 3 - butanediol
    B
    2 - methyl - 2, 4 - pentanediol
    C
    4 - methyl - 2, 4 - pentanediol
    D
    1, 3, 3 - trimethyl - 1, 3 - propanediol

  • What is the product of the following reaction : CH_(3)-underset(CH_(3))underset(|)(C )=CH_(2) overset(HBr)underset("Peroxide")rarr

    A
    `CH_(3)-underset(CH_(3))underset(|)(C )-H-CH_(2)-Br`
    B
    `CH_(3)-overset(Br)overset(|)underset(CH_(3))underset(|)(C )-CH_(3)`
    C
    `CH_(3)-underset(CH_(3))underset(|)(C )H-underset(Br)underset(|)(C )H-Br`
    D
    None of these

  • CH_(3)-underset(CH_(3))underset(|)overset(CH_(3))overset(|)(C)-underset(OH)underset(|)(CH)-CH_(3)overset(HBr)rarrA (predominant) A is

    A
    `(CH_(3))_(3)C-overset(Br)overset(|)(CH)-CH_(3)`
    B
    `(CH_(3))_(2)overset(Br)overset(|)(C)-CH(CH_(3))_(2)`
    C
    Both
    D
    none of the above

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    CH_(3)-underset(CH_(3))underset(|)(C)=CH-underset(CH_(3))underset(|)overset(CH_(3))overset(|)C-CH_(3)

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    The IUPAC name of CH_(3)-underset(OH)underset(|)(CH)-underset(CH_(3))underset(|)(CH)-underset(OH)underset(|)(CH)-overset(" "CH_(3))overset(|)underset(" " CH_(3))underset(|)(C)-CH_(3) is:

    The IUPAC name of CH_(3)-CH_(2)-underset(CI)underset(|)(CH)-underset(CH_(3))underset(|)(CH)-overset(CH_(3))overset(|)underset(OH)underset(|)(C)-CH_(3) is :

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