Full Name______

Chemistry 3013-01

The University of Tulsa Department of Chemistry & Biochemistry

Organic Chemistry I

Final Examination December 16, 2014 9:00 to 11:25 AM

DO NOT OPEN THIS EXAM UNTIL DIRECTED TO DO SO

When the exam begins, please look through every question to assess how to best allocate your time. You must answer all questions. Three optional bonus problems are also available; each is worth up to 20 points. The point value for each question is designated in parentheses after each problem. The exam will last from 9:00 AM until 11:25 AM. When time is called, you must put down your pen or pencil immediately and hand in the exam. Please write and draw as clearly as possible in the space provided. If you require additional space and continue an answer on the back of a page, you must clearly indicate this to the grader.

Question 1: Predicting products of organic reactions (20 pts) ____ Question 2: Reagent selection in organic synthesis (20 pts) ____ Question 3: Substitution and elimination reactions (40 pts) ____ Question 4: Named reactions in organic synthesis (40 pts) ____ Question 5: Rearrangements in elimination reactions (20 pts) ____ Question 6: Kinetic isotope effects (20 pts) ____ Question 7: Mechanisms of rearrangement reactions (40 pts) ____ Bonus 1: Solvent effects in substitution reactions (20 pts) ____ Bonus 2: Syn-elimination of selenoxides (20 pts) ____ Bonus 3: Nucleophilic aromatic substitution (20 pts) ____

Total ____

1 Question 1: Predict the major product for the following reactions. Draw your proposal in the box provided. Clearly account for stereochemistry where applicable. The chemical formulas for the desired products are given to assist in your prediction. No explanation is required. (4 x 5 pts)

O NaN3

CH3CN Cl C5H9N3O

Br

KOtBu

tBuOH C8H14

OH MeOH Ph Ph H SO (cat.) C H O Ph 2 4 20 18

O MeOH C H O NaOMe (cat.) 5 12 2

2 Question 2: Suggest appropriate reagents and reaction conditions to promote the following reactions. More than one step may be required. Write your proposals in the box above the reaction arrow. If more than one step is necessary, number each step. Be sure to account for stereochemistry and regiochemistry, where applicable. No explanation is required. (4 x 5 pts)

OH Cl

OH NH2

Ph Ph

SH S

O OH

3 Question 3: Give specific examples of reactions that satisfy the criteria specified below. Clearly specify all reagents, solvents, and relevant reaction conditions in your proposals. (4 x 10 pts) i) Draw a substitution reaction that results in racemization

ii) Draw a stereospecific elimination

4 (Question 3 continued) iii) Draw a substitution reaction that features a carbocation intermediate.

iv) Draw an example of a regioselective elimination.

5 Question 4: For one of the following named reactions, give a specific example of that reaction type, along with a full arrow-pushing mechanism. Comment on relevant stereochemical and regiochemical outcomes for your reaction where relevant. (40 pts)

Finkelstein reaction Appel reaction Hoffman elimination Gabriel synthesis of amines Zaitsev elimination / Zaitsev’s rule

6 (Question 4 continued)

7 Question 5: Propose a full arrow pushing mechanism for the following reaction. What is the thermodynamic driving force for this transformation? (20 pts)

OH

H2SO4 heat

8 Question 6: Give an example of a reaction where you would expect to observe a small primary kinetic isotope effect. Clearly explain how this effect is related to the mechanism of your reaction and how it provides information about the rate-determining step. (20 pts)

9 Question 7: Propose an arrow pushing mechanism for the following reaction. Hint: consider in intramolecular cyclization as a first step. Next, discuss an experiment that would provide evidence for any intermediate you propose. (40 pts)

N N heat Cl

Cl

10 (Question 7 continued)

11 Bonus 1: Explain how the solvent can influence the rate of an SN2 reaction. Illustrate with a specific example. (20 pts)

12 Bonus 2: Propose a mechanism for the following reaction. Hint: The selenium first behaves as a nucleophile and attacks the peroxide electrophile. (20 pts)

O O

SePh H2O2

13 Bonus 3: Explain why the following reaction is probably not an SN2 reaction. Propose an alternative mechanism. (20 pts)

Cl OH NO 2 NO KOH 2

H2O

NO2 NO2

14