Conversion of alcohols to alkyl halides using HCl

by James

Description: Treatment of tertiary alcohols with HCl leads to formation of tertiary alkyl chlorides.
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Notes: This proceeds through an SN1 mechanism. The reaction also works for other alcohols that form stable carbocations, such as allylic and benzylic alcohols.

Examples: 

Notes: Note that in the third example, since a stereocenter is present, a mixture of stereoisomers (enantiomers) will be formed since the reaction proceeds through an SN1 reaction.

Mechanism:

Notes: If the alcohol were on a stereocenter we would obtain a mixture of stereoisomers.

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{ 5 comments… read them below or add one }

Sumera

What are the benefits or importance of converting alcohols to alkyl chlorides?

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james

Great question! Alcohols don’t have a good leaving group, so they don’t undergo substitution or elimination (except under acidic conditions). However once you convert them to alkyl chlorides, you can then turn them into all kinds of other useful functional groups.

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Rashmi Singh

For the third example, does chirality remain or change?

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james

You get a mixture of retention and inversion, which leads to a mixture of enantiomers. I updated the image to make it more clear. Thanks for asking.

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Robert Eursiriwan

In the third example, which product is favored?

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