Tuesday, April 10, 2012

Lucas Test for Secondary and Tertiary Alcohols

1-Butanol, 2-Butanol, t-Butyl alcohol.

To 0.2 mL or 0.2 g of the unknown in a test tube add 2 mL of the Lucas reagent at room temperature. Stopper the tube and shake vigorously, then allow the mixture to stand. Note the time required for the formation of the alkyl chloride, which appears as an insoluble layer or emulsion.
The Lucas reagent is already prepared for you.

Positive test
Appearance of a cloudy second layer or emulsion

3o alcohols: immediate to 2-3 minutes
2o alcohols: 5 -10 minutes
1o alcohols: no reaction

The test applies only to those alcohols soluble in the reagent (monofunctional alcohols lower than hexyl and some polyfunctional alcohols.) This often means that alcohols with more than six carbon atoms cannot be tested.

Cleaning Up
Place all solutions in the appropriate waste container.


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