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Nucleophilic Substitution of Alcohols

This was an experiment done in lab class. The the following alcohol was reacted with hydrochloric acid in presence of zinc chloride (HCl-ZnCl2) and the result:
1. 1-butanol; test tube has no color change, clear liquid
2. 2-butanol; test tube had two layers formed, top lawer lookes white and oily
3. 2-methyl-2-propanol (tert-butanol); tube tube was white and murky

I need help with the following questions:
1. Write balance equation for the following two reactions with HCl-ZnCl2 that occurred
a. 2-butanol
b. 2-methyl-2-propanol (tert-butanol)
2. By which mechanism (SN1 or SN2) did these reactions occur? How do you know? (Assume both react by the same mechanism)

Solution Preview

Hydrochloric acid alone reacts poorly with primary alcohols and secondary alcohols, but a combination of HCl with ZnCl2 (known together as the "Lucas reagent") at 130 °C is effective for the preparation of alkyl chlorides. This probably reacts via an SN2 mechanism with primary alcohols but via SN1 with secondary alcohols.

Under the condition of ...

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