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Which of the following alcohols can be s...

Which of the following alcohols can be synthesized from an alkene with the same number of carbon atoms by means of hydroboration -oxidation ?
(i) Butan-`2-ol`
(ii)`1`-Methylcyclohexanol
(iii)Isobutylbutan-`2-ol`
(iv) Cyclopentylcarbinol
(v) `2`-Methylbutan-`2-ol`

A

`(i),(ii),(v)`

B

`(iii),(iv)`

C

`(ii),(iii)`

D

`(ii),(iii),(v)`

Text Solution

Verified by Experts

The correct Answer is:
B
Treatment with `BH_(3)-THF` followed by oxidation with `H_(2)O` in `aq.OH^(-)` gives the anti-Markovnikor addition for the synthesis of (iii) and (iv)
`(CH_(3))_(2)C = CH_(2) underset((2)H_(2)O_(2),OH^(-))overset((1)BH_(3)-THF)rarr (CH_(3))_(2)underset("Isobutyl alcohol")(CHCH_(2)OH)`

In preparing (i),(ii) and (v), Markovnikov addition to a double is required which can be accomplished by hydration in the presence of dilute `H_(2)SO_(4)` or by oxymercuration with `Hg(OAc)_(2)//H_(2)O` followed by reduction with `NaBH_(4)`.
`underset(CH_(3)CH_(2)CH = CH_(2))overset(CH_(3)CH = CHCH_(3))(or)rarrunderset("Butan-2-ol")(CH_(3)CH_(2)overset(OH)overset(|)(CHCH_(3)`

`underset(H_(2)C = underset(CH_(3))underset(|)(C)CH_(2)CH_(3)) overset((CH_(3))_(2)C = CHCH_(3))(or) rarrCH_(3)-underset(OH)underset(|)overset(CH_(3))overset(|)(C)-CH_(2)CH_(3)`
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