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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)

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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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