Chemistry Workshops
1. Low molecular weight alcohols dissolve in concentrated hydrochloric acid containing ZnCl2. For some alcohols, a reaction takes place to form a new compound that is insoluble in concentrated HCl/ZnCl2. Thus, a clear solution of the alcohol in the reagent turns cloudy. The rate of formation of this new product varies with structure.
(CH3)3COH > C6H5CH2OH ~ CH2 = CHCH2OH ~ (CH3)2CHOH > CH3CH2CH2OH
What is the insoluble product? Give a balanced equation for the reaction that occurs. Write a mechanism for formation of the insoluble product. Explain how your mechanism accounts for the relative rates of reaction. Be sure to specify a role for the ZnCl2.
2. When ethanol is added to chromic acid, CrO3/H2SO4/H2O, the solution changes from orange to blue-green. This reaction forms the basis of the "Breathalyzer" test used to catch drunk drivers. Write a balanced equation for the reaction.
3. When an alcohol reacts with SOCl2 / pyridine, the derivative shown below is formed. If the reactant alcohol is (S)-1-deuterioethanol, the product is (R)-1-deuterioethyl chloride. Clearly explain how the formation of this intermediate facilitates the conversion of the alcohol to the corresponding alkyl chloride. Explain the stereochemical change.
4. Write synthetic sequences for the following compounds, beginning only with alcohols having four carbons or fewer.
Materials adapted from:
Peer-Led Team Learning: Organic Chemistry, 1/e
Jack A. Kampmeier, University of Rochester
Pratibha Varma-Nelson, St. Xavier University
Donald Wedegaertner, University of the Pacific
Prentice-Hall, 2001, ISBN 0-13-028413-0
http://www.sci.ccny.cuny.edu/~chemwksp/OrganicChem.html