Download Organic Chem Exam 3 - Enantiomers, Diastereomers, Conformations and more Exams Organic Chemistry in PDF only on Docsity!
Name:
Organic Chemistry - CHEM 231A
Test # November 5, 2001
- Provide answers to the following questions: (30 points)
1a. What is an enantiomer? Provide examples that represent the concept and explain. (5 points)
1b. What is an diastereomer? Provide examples that represent the concept and explain. (5 points)
1c. What is a meso compound? Provide an example that represents it and explain why it is a good example. (5 points)
1d. What is a transition state? Provide an example that represents it and explain why it is a good example. (5 points)
1f. What forces affect the stability of cycloalkanes? Provide examples, drawings and an explanation. (10 points)
- Name or provide structures for the following molecules (4 @ 5 pts = 20 points)
2a.
Br
2b.
OH
H 3 CO
2c.
Br
2d. [2S,3R,4S,5R] 2-bromo-4-t-butyl-5-chloro-3,6-diethyloctane
- Consider the following reaction: (36 points)
F
F
F
Cl 2 / hν
Observed Specific Optical Rotation α = + 63o
F
F
F
4a. Provided that the specific optical rotation for pure (2S)-1,1,1,4,4,4-hexafluoro-2-methylbutane is
- 92°, what is the optical purity of the starting material? What does optical purity mean? ( points)
4b. What is(are) the configuration(s) of the starting material(s) If there is more than one starting material, what percentage of each exists? Show your work. (10 points)
4c. What is(are) the major product(s) for this reaction? (8 points)
4d. What is the enantiomeric excess for each product? Explain. (12 points)
- Consider the following molecules or sets of molecules: (20 Points)
5a1. Given the Fischer projection of ibuprofen, which enantiomer is depicted. (2 points)
H CH (^3)
HO O
H 3 C H
H H
CH 3
5a2. Redraw the same configurational isomer using bond-line drawings. (3 points)
5b. Given the following two molecules, describe the isomeric relationship that exists between them. Explain. (5 points)
Br
OH
H
Br
HO
H
5c. Draw all stereoisomers for 2,5-dicyano-3,4-dimethylhexane. Label the isomeric relationships between each molecule (10 points)
