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Chemistry 2131:
Organic Chemistry for the Life Sciences

Assignment #4

Please read the instructions for completing assignments on the main "Assignments" page.

This assignment is due at the beginning of class on November 6th or before.

1. Give structures of the following indicating proper stereochemical orientation:

  1. (R)-2-iodobutane
  2. (S)-2-iodobutane
  3. (R)-1-chloro-1-propanol
  4. (S)-3-methyl-3-hexanol
  5. (S)-1-bromo-1-chlorobutane
  6. (2R,3R)-2,3-dichloropentane

2. Take a look at Table 12.1 on page 337 of the text book. Consider the third line, the 5 carbon aldoses. Shown are the D-sugars (we'll learn why they are called D in a while). Each one also has an enantiomer called an L-sugar. Draw Fischer projections of all of the 5 carbon aldoses (including the L ones) and give the proper IUPAC name for each (including stereochemical designations of course!).

3. For the following reagents and solvents, decide which reaction is likely to prevail (SN1, SN2, E1 or E2) and give the mechanism of the reaction. Name the products.

  1. 1-bromopentane reacts with ethoxide in ethanol
  2. 1-bromopentane reacts with tert-butoxide in tert-butanol
  3. (R)-2-bromobutane reacts with the hydroxide ion in water
  4. cis-1-tert-butyl-4-chloro cyclohexane reacts with iodide in acetone
  5. (S)-3-bromo-3-methylhexane reacts with methanol in methanol

4.Explain the following observations: When tert-butyl bromide (2-bromo-2-methylpropane) is treated with sodium methoxide in a mixture of methanol and water, the rate of formation of tert-butyl alcohol and tert-butyl methyl ether does not change appreciably as the concentration of sodium methoxide is increased. Increasing the concentration of sodium methoxide, however, causes a marked increase in the rate at which tert-butyl bromide disappears from the mixture.