351 Organic Chemistry II



351 Organic Chemistry II Winona State University

Exam #1a, 2/12/2007 Professor T. Nalli

Answers

General Instructions: Write your name in the space provided above and on the provided Scan-tron form. Do not put your name anywhere else in this exam book.

Make sure that you read each question carefully and provide complete answers. Time limit is 55 min. Exams must be turned in immediately upon my call of time up.

Grading: Grading will be on the basis of a highest possible score of 100 points.

I. Multiple Choice – 3 points each, 30 points total

II. Nomenclature/Structure - 2 points each, 20 points total

III. Reaction Products – 6 points each, 42 points total

IV. Mechanism Problem – 5 pts

V. Synthesis Problem – 5 pts

Extra Credit – You will receive 5 extra points if you fill out and submit the Assessment Day survey on Assessment Day.

I. Multiple Choice

1. Which of these fatty acids has the highest melting point?

A. octadecanoic acid (stearic acid)

B. cis-9-octadecenoic acid (oleic acid)

C. trans-9-octadecenoic acid (elaidic acid)

D. cis,cis-9, 12-octadecadienoic acid (linolenic acid)

2. Which of these compounds exists as geometric (cis/trans) isomers?

A. 1-hexene B. 2-hexene C. cyclohexene D. 2-hexyne

3. Which of the following is not a mechanism by which cis/trans isomerization of an alkene can happen?

A. catalytic hydrogenation then catalytic dehydrogenation

B. protonation by a strong acid then deprotonation

C. light-initiated enzyme-catalyzed hula twist

D. ozonolysis then deozonolysis

4. What is the stereochemical designation for each compound shown below?

A. I is E. II is Z. B. I is Z. II is E. C. Both are E D. Both are Z

5. Which base would be least effective for the deprotonation of a terminal alkyne?

A. n-BuLi B. NaOH C. NaH D. NaNH2

6. What factors control the regioselectivity of hydroboration of alkenes using BH3/THF?

A. Electronic B. Steric C. Both electronic and steric D. Neither electronic nor steric

7. Which effect determines the fact that terminal alkynes are more acidic than saturated hydrocarbons? A. resonance B. inductive C. hybridization D. steric

8. Which term best decribes the shape of the acetylene (C2H2) molecule?

A. trigonal planar B. tetrahedral C. linear D. bent E. square planar

9. Rank the following carbocations in order of decreasing stability.

A. II > I > III B. II > III > I C. I > II > III D. III > II > I

10. Which of these is a palladium catalyst used for the hydrogenation of alkynes?

A. Lindlar catalyst B. Kevlar catalyst C. Helm Bar catalyst D. mercury (II) sulfate

II. (a) Draw a structural representation of each of the following.

1. 4-isobutyl-2-methylcyclohexene 2. octa-1,7-diyne

3. (E)-4-octene 4. cyclooctyne

5. bicyclo[4.1.0]hept-1-ene 6. diborane

II. (a) Name each of the following.

III. Give the structure(s) of the main organic product(s) of each of the following reactions. Where the reaction is expected to be stereoselective then show the stereochemistry of the product actually formed.

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IV. Write out the mechanism of the reaction shown using curved arrows to show the movement of electrons in each step.

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V. Outline a multi-step synthesis that would allow one to prepare 2-pentanone starting from 1-pentene. Hint: use an alkyne reaction for the last step.

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