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Organic Chemistry Quiz: CHM 220-2, Quiz #4, Exams of Organic Chemistry

A rollins college organic chemistry quiz consisting of multiple-choice questions and problems related to organic chemistry concepts such as configurational isomers, stereochemistry, and reaction mechanisms. The quiz covers topics like optical rotation, nmr, gc, and chiral gc, and includes questions that require the interpretation of data and the prediction of products and mechanisms.

Typology: Exams

Pre 2010

Uploaded on 08/03/2009

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Name:
Rollins College
Organic Chemistry: CHM 220-2
Test # 3
100 Points Total
April 19, 2006
1. Completely describe the concept of configurational isomers. Include subcategories, definitions and
relevant structures to provide a complete analysis of what configurational isomers are. (15 pts)
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Name: Rollins College

Organic Chemistry: CHM 220-

Test # 3

100 Points Total April 19, 2006

  1. Completely describe the concept of configurational isomers. Include subcategories, definitions and relevant structures to provide a complete analysis of what configurational isomers are. (15 pts)
  1. Consider the following molecule and series of reactions to answer the questions (20 pts)

?

[α]D = + 20

Data

[α]D = 0

20

In addition to the above products: NMR shows 1 additional product GC shows 1 addditional product Chiral GC shows 2 additional products in equal abundance with respect to each other All products were separated using non-chiral methods and the optical rotation was obtained for "the new compound" (the one that showed one molecule in the NMR) yielding the following results:

?

[α]D = + 20

Data NMR shows 2 products GC shows 2 product Chiral GC shows 2 products The products were separated using non-chiral methods and the optical rotation was obtained for each compound yielding the following results:

[α]D = - 20 Product A

Excess HCl 10 times excess of NaCl

[α]D = + 20 Product B

HCl (1 eq) added dropwise Reaction was heated

New compound as seen by NMR

2a. Considering ONLY the information / data provided with the starting material (not any of the reactions), explain what is meant about the information assuming that the starting material is optically pure. (4 pts)

2b. Considering ONLY the information / data provided with the starting material (not any of the reactions), if a bottle in the stockroom has an NMR that matches the NMR of the starting material as drawn, but has an optical rotation of -12, what does this mean, both qualitatively and quantitatively? (6 pts)

  1. Consider the following reactions. Predict the best answer to complete the question mark. Mechanisms are NOT required, but may be used. Pay close attention to stereochemical issues: ( points – 10 points for each)

3a.

3b.

Br 2 / CH 2 Cl 2 ?

OH

?

?

OH

Br

3c. HCl / H 2 O ?

3d.

  1. BH 3 / THF
  2. H 2 O 2 / NaOH / H 2 O?

OH

  1. Bob (our favorite organic chemistry student, who is taking organic for 13th^ time) was walking through the stockroom and found a bottle labeled with Z (2R, 3S, 4S) 4-isopropyl-6-methyl 3-phenyl-4-oct-5-en- 2-ol. He thought it was a cool molecule and decided to do a reaction with it. He predicted the following reaction. (25 pts)

Z (2R, 3S, 4S) 4-isopropyl-6-methyl

3-phenyl-4-oct-5-en-2-ol

O

HCl

4a. What is the structure of Z (2R, 3S, 4S) 4-isopropyl-6-methyl 3-phenyl-4-oct-5-en-2-ol? (6 pts)

4b. Is the product that Bob predicted correct or not? Why or why not? (3 pts)

4c. If it is the correct product, draw a mechanism that accounts for its formation. If it is not the correct product, draw a mechanism that forms the correct product. (10 pts)

4d. Would you predict that there is another product (as observed by NMR) formed in this reaction? Why or why not? If so, what is it and how is it related to your answer in problem 4c? (6 pts)

  1. Consider the following reaction (6 pts)

HCl / CH 3 OH

2a. What would be the major product under kinetic control for the following reaction (low temperature)? Briefly explain your answer. (3 pts)

2b. What would be the major product under thermodynamic control for the following reaction? Briefly explain your answer. (3 pts)