Alcohols and Ethers - Result Question 3

4. The major product of the following reaction is

(2019 Main, 9 April I)

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(a)

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(b)

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(c)

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(d)

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Answer:

Correct Answer: 4. (c)

Solution:

$PBr _3$ reagent is used for the substitution of $-Br$ group while alc. $KOH$ reagent is used to carry out elimination reaction.

The given reaction proceed in following manner:

Step I: In presence of $PBr _3$, alcohols undergo substitution reactions to give halides. Reagent $PBr _3$ is usually generated insitu by the reaction of red phosphorus with bromine.

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Step II: 3-bromohexanone in presence of alc. $KOH$ undergoes elimination reaction and gives cyclohex-2-en-1-one.

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