EXAM 3

CHEMISTRY 220a

Friday, November 5, 2004

 

NAME (print): ___________________________________________________

 

TA:_____________________    Day:_________________ Time:__________

 

 

Take a few moments to look over the exam.  Answer each question on the exam paper.

 

Important clues, points, and structures are in bold.

 

 Do all preliminary drawing or computations on the work sheets at the end of the exam. The work sheets will not be graded

 

The exam is 55 minutes.

 

STOP writing and hand in your exam when you are asked to do so.

 

Remember: Neatness is to your advantage.

 

1. Structure  (25 pts)               ______

 

 

2.  Synthesis  (25 pts)             ______

 

 

3.  Reactions (25 pts)              ______

 

 

4.  Potpourri (25 pts)               ______

 

 

_______________________________

 

Total (100 pts) 


1.           Structure: (25 pts.)  Compound (S)-A  (C10H16) reacts with H2 in the presence of Pd to form achiral B (C10H20) and achiral C (C10H20). Ozonolysis and dimethyl sulfide reduction of A affords the single enantiomer D and formaldehyde.  What are the structures A-D? Explain and illustrate.  Be certain to illustrate the absolute stereochemistry for A and D.

 

2.  Synthesis: (25 pts.)  A chemist requires a sample of (±)-epoxide 1.  She designs and executes a synthesis of the epoxide using 1-butyne as her sole source of carbon. All other reagents are available to her.  Show how she may have accomplished her goal.

 

3. Reactions:  (25 pts.) Provide the reaction conditions in 4 of 5 of the following chemical transformations. Several steps may be required.  If you do all five problems, cross out the one you do not want graded. Pay attention to stereochemistry.

 

 

 

4.  Potpourri: (25 pts.)  Complete 4 of 5 of the following. If you do all five problems, cross out the one you do not want graded.

 

              a)  Provide (over the arrow) the catalytic agent in each of the following single-step reactions.

 

 

 

              b)  Circle the reagents that are expected to give meso compounds with (Z)-5-decene .

 

 

                        Br2       Br2/H2O          peracid             OsO4/H2O2     CH2I2/Zn(Cu)

 

 

c)     The heat of formation of 2-hexyne is +25.7 kcal/mol.  Circle the most likely heat of formation of 1-hexyne.

 

+29.2              +25.7              +25.2              +20.2              -29.2                         

 

 

 

d)    Circle the compound(s) in violation of BredtŐs Rule.

 

 

e)     (Circle all that apply.)  Hydroboration and oxidation of 2-methyl-2-butene affords an alcohol that is:

 

optical-active        racemic           secondary        tertiary             d,l

 

 

      Work Sheets
      Work Sheets
      Work Sheets