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Lucas Test for Primary, Secondary, and Tertiary Alcohols

1-butanol, 2-butanol, and 2-methyl-2-propanol are treated with a solution of ZnCl2 in concentrated aqueous HCl.

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3.1 MB, 50 seconds

File: MOVIES/TRAM11/0362502.MOV

Voiceover
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.

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.


       

Citation:  
  Shriner, R. L.; Fuson, R. C.; Curtin, D. Y.; Morrill, T. C. The Systematic Identification of Organic Compounds; 6th ed.; Wiley: New York, 1980; pp 204-206.
Design, Text and Demonstrator:  
  Gary Trammell University of Illinois at Springfield, Springfield, IL 62794
Videographer/Editor:  
  Steve Dykema University of Illinois at Springfield, Springfield, IL 62794
Voice:  
  Margaret Biddle University of Wisconsin - Madison, Madison, WI 53706
Audio Production:  
  Greg Minix University of Wisconsin - Madison, College of Engineering, Madison, WI 53706
  Jerrold J. Jacobsen University of Wisconsin - Madison, Madison, WI 53706