Chemistry 220 Assignment 5 by woo44846


									Chemistry 220 Assignment 5

Problems from the text: Chapter 4, problems 4-34(a-c, h,n,p), 4-39, 4-43, 4-47; Chapter
5, problems 5-25, 5-28, 5-29, 5-30, 5-32

Quiz problems:

   1. The free radical formed from toluene, by the process shown below, is even more
      stable than a tertiary free radical. Explain why.
                 C H                                   H
                                                              +                H

   2. Give the mechanism for the free radical bromination of ethane. Label each step,
      and also give the overall reaction.

   3. A sample of a pure liquid in a 10-cm (that’s 1 dm) tube is placed in the
      polarimeter and the reading is +45o. How could you tell that it is really +45o and
      not -315o? After all, that would look the same on the dial (think about it, there are
      360 degrees in a circle). As a start, consider the lab you did last week.

   4. What is the specific rotation of cholesterol, based on the following observation: a
      sample of 6.15 g of cholesterol in 100 mL of solution gives an observed rotation
      of -1.2o when placed in a 5 cm polarimeter tube. What would the observed
      rotation be if we used a 10 cm tube?

   5. Draw and label as R and S, both enantiomers (if any) of:
         (a) 3-chloro-1-pentane
         (b) 3-chloro-4-methylpentane
         (c) malic acid (look it up, not maleic acid)
         (d) methamphetamine

   6. Draw the molecules from the previous question in Fischer projection.

   7. Draw stereochemical (wedge and hatch) structures for all the possible
   stereoisomers of the following compounds. Label pairs of enantiomers. Pick out
   examples of diastereomers.
           (a) 1,2-dibromopropane
           (b) 2,4-dibromopentane
           (c) 1-chloro-2-methylbutane
           (d) 2-bromo-3-chlorobutane

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