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Name: _____________________________________________________ CHM 235IN SPRING 08 EXAM II

1. (6pts)

Classify each structure below as a nucleophile or electrophile and briefly explain your choice.

Nucleophile

Electrophile

Nucleophile or Electrophile

2. Label the electrophile and nucleophile in the following reaction: (4pts)

Electrophile Nucleophile

3. Calculate the degrees of unsaturation in diazepam (Valium), [pic] (2pts)

16 *2 +2 = 34 -13H - 1Cl = 20 plus 2 for Nit = 22 22/2 = 11 degrees

4. Label any double bonds as E or Z if needed in the following molecules (8pts)

Z E

5. Using examples: Discuss the terms “hydride shift” and “methyl shift”. (10pts)

See text for examples: Important note: hydride or methyl shifts happen on a carbo cation intermediate that can move to make a more stable intermediate. The shift would happen to open up a tertiary or secondary spot.

6. Draw the complete mechanism for the reaction below: (4pts)

[pic]

[pic]

7. For the reaction in problem 6, draw a qualitative reaction energy diagram for this reaction.

Label the positions of all reactants, intermediates and products. (6pts)

[pic]

8. Using your reaction diagram, carefully explain the Hammond postulate: (10pts)

The Hammond postulate explain the structure of the transition state based on the closest stable reaction participate. In the above diagram the first transition state is closer in energy to the carbocation intermediate and should look similar to that structural. It should be a planar transition state. The second transition state is also closer to the structure of the interemediate in this case. This is not always the case. Knowing the structure of the intermediate helps the chemists to developing ways to influence the reaction pathway by influencing the transition state.

9. Write the complete...