Lucas Test for Primary, Secondary, and Tertiary Alcohols

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Summary

1-butanol, 2-butanol, and 2-methyl-2-propanol are treated with a solution of ZnCl2 in concentrated aqueous HCl. Click on any image to enlarge it.

Video

These images are associated with the video Lucas Test for Primary, Secondary, and Tertiary Alcohols

Video Narration

Three test tubes contain a solution of zinc chloride (ZnCl2) in concentrated aqueous hydrochloric acid (HCl). The primary alcohol 1-butanol, the secondary alcohol 2-butanol, and the tertiary alcohol 2-methyl-2-propanol are added to separate test tubes. Immediately the tertiary alcohol forms a cloudy solution as the alcohol is converted to the water insoluble alkyl chloride by a SN1 reaction. The primary alcohol, 1-butanol, does not react. The secondary alcohol, 2-butanol, reacts after about 6.5 minutes.

Video Discussion

In sequence, 1-butanol, 2-butanol, and 2-methyl-2-propanol are treated with a solution of ZnCl2 in concentrated aqueous HCl. Immediately the tertiary alcohol forms a cloudy solution as the alcohol is converted to the water insoluble alkyl chloride by a SN1 reaction. The secondary alcohol, 2-butanol, reacts after about 6.5 minutes. The primary alcohol, 1-butanol, does not react.

Keywords

Alcohols | Constitutional Isomers | Kinetics | Molecular Properties / Structure | Nucleophilic Substitution

Included in These ChemEd DL Resource Groups

Alcohols

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