EXAM 2

CHEMISTRY 225b

Friday, March 28, 2008

 

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. (30 pts)  Reactions (5 of 6)             ______

 

 

2.  (30 pts) Potpourri                           ______

 

 

3.  (20 pts) Structure                           ______

 

 

4.  (20 pts) Mechanisms (1 of 2)         ______

 

 

_____________________________________

 

Total (100 pts) 


1.  (30 pts.) Reactions:  Provide the required information in 5 of 6 of the following reactions.  Pay attention to stereochemistry, optical activity, etc.  If you do six problems, cross out the one that you do not want graded.

 

 

 


2. ContinuedÉ

 


2.  (30 pts.) Potpourri: Complete each of the following problems.

 

a)     (R, R)-Tartaric acid has [a] = +12o.  What is the specific rotation of a 2:1 mixture by weight of meso-tartaric acid and (S, S)-tartaric acid, respectively? Show work.

 

 

 

 

 

 

 

 

b)  Circle the compounds that are capable of resolution.

 

 

 

c)     Circle the terms that apply to E2 eliminations.

 

concerted                                 deuterium isotope                    rate=k[RX]

                                                                        effect   

        

          orbital overlap                                       rate=k[RX][Nuc]                    

 

 

 

d)  Circle the alcohol(s) that represent the racemates formed by the hydroboration of (E)-3-methyl-2-hexene.

 

 

e)  The normal chain hexene that gives a single product upon ozonolysis and is more stable by ~1 kcal/mol than its geometrical stereoisomer.


3. (20 pts.) Structure: Compound A, C8H16, forms a meso compound B upon reaction with bromine in CCl4 and forms d,l-diol C upon oxidation with OsO4/H2O2.  Ozonolysis of A forms a single ketone D.  What are the structures of A-D? Show your reasoning.


4.     (20 pts.) Mechanisms:  Provide a detailed mechanism for one, and only one,  of the reactions shown below. Use the curved arrow formalism.  Pay attention to stereochemistry, and the absence of stereo- and regioisomers as these issues may apply.

 


 Work Sheets
      Work Sheets
      Work Sheets