Chemistry 332 - Winter 1997

Quiz, Chapter 12

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1. (2 points) Write the major form (conjugate acid or conjugate base) that you would expect for the following compounds at pH 7. Write the chemical formula the best you can.

Example: ammonia // Answer: NH4+

a) dimethylamine / / (CH3)2NH2+

b) acetic acid / / CH3COO-

c) alpha-aminoacetic acid / / +H3NCH2COO-

2. (2 point) Refer to the structure of heroin on page 371 of your textbook. Give its molecular formula and identify the number of stereocenters.

C21 H23 N1 O5

5 stereocenters

3. (2 points) When pyrrole undergoes electrophilic substitution by bromine, the intermediate has a positive charge delocalized to which positions? (use numbers based on the standard numbering system for pyrrole)

positions 1, 3, and 5

The bromo substituent ends up on which position?

position 2

4. (4 points) Describe the sequence of steps you could use to synthesize p-(dimethylamino)azobenzene starting from benzene.

Example: benzene + HNO3/H2SO4 --> nitrobenzene

1) benzene + HNO3/H2SO4 --> nitrobenzene

2) nitrobenzene + Fe/HCl --> aniline

3) aniline + HNO2/HCl --> benzenediazonium chloride

4) aniline + 2 CH3I --> N,N-dimethylaniline

5) benzenediazonium chloride + N,N-dimethylaniline --> p-(dimethylamino)azobenzene