CE 232 rganic Chemistry II Exam 4 ame: KEY Student number: Before you begin this exam: First: You are allowed to have a simple model set at your seat. Please put away all other materials. Second: Place your student identification on your desk. A proctor will come around to check everyone s ID. Third: Read through the entire exam. Your goal, as always, is to score as many points as possible. Do not waste time on problems that you can t do if there are others that look easy. Fourth: READ EAC QUESTI CAREFULLY. Be sure you answer the question that is asked. 1. 10 points 2. 15 points 3. 10 points 4. 10 points 5. 10 points 6. 20 points 7. 25 points 8. 20 points 14. 20 points 15. 20 points 16. 15 points 17. 10 points 18. 10 points 19. 6 points 20. 10 points 21. 20 points 9. 20 points 10. 10 points 11. 25 points 12. 4 points 13. 10 points Total: 1
1. (10 points) In the series of radicals below, label one as the MST STABLE and one as the LEAST stable in the series. C 2 C 2 C 2 LEAST MST 2. (15 points) Draw a detailed mechanism for the radical chain bromination of cyclohexane. Write your mechanism as a series of steps: initiation step, propagation steps, and at least two different termination steps. 2, h! + Initiation step: h! 2 Propagation steps: + + Termination steps:, 2 2
3. (10 points) For each of the following transformations, provide the expected product or the reagents required to bring about the reaction shown. a) (product needed) 2, h! b) (reagents needed), peroxide initiator 4. (10 points) Give the IUPAC name for the following compound. Use the E, Z designation if appropriate. C 3 E-1-bromo-1-chloropropene 5. (10 points) Draw the structure that corresponds to each name a) E- 4- ethyl- 3- heptene b) 4- vinylcyclopentene 3
6. (20 points) Draw the organic products formed in the following reactions. Pay attention to regiochemistry and be sure to show the expected stereochemistry if a specific isomer is expected. a) C C C 2 C 3 excess 2 Pd/C b) c) 2 d) 1. B 3 C 3 2. 2 2, C 3 7. (25 points) Predict the product of the following reactions. If you anticipate a mixture of two isomers, please show them both. a) 3 2 2 C 3 2 S 4 C 3 C 3 4
b) 3 2 C 3 2 S 4 C 3 c) 2 2 2 Pd/C d) 2 Fe 3 e) C 3 C 2 KMn4 5
8. (20 points) Draw a detailed, stepwise mechanism for the following reaction. + Al 3 Al 3 3 Al 6
9. (20 points) Show how the compound below could be made from benzene. Be sure to show the reagents needed for each step, and the product formed after each step in your synthesis. C 2 C 3 Ac, Al 3 C 3 2, Fe 3 Zn(g), C 2 C 3 10. (10 points) Acetal formation is a reversible process, and that makes these structures very useful as protecting groups. a) In the reaction shown above, what specific reagents are needed to convert the ketone to the acetal? Ethylene glycol, tosic acid, dry conditions b) What specific reagents are needed to convert the acetal back to the ketone? Water, (wet acid) 7
11. (25 points) Provide the expected organic product from the reactions below. a) Ph 3 P b) C 2 Et ab 4 C 2 Et c) C 2 Et 1. LiAl 4 2. 2 d) 2 Ts e) 1. Mg 2. 2 8
12. (4 points) Which of the following is the most reactive (most electrophilic) acylating agent? (circle one) 2 Et 13. (10 points) In the series of carboxylic acids below, label the LEAST acidic one and label the MST acidic one. C 2 C 2 C 2 C 2 C 2 C 3 2 2 C 3 most least 14. (20 points) Provide the reagents needed to bring about the following trans- formations. In some cases, more than one step may be required. a) Et catalytic 2 S 4 Et b) C 2 C 3 1. LiAl 4 2. 2 C 2 9
c) 1. S 2 C 2 C 3 2. Et 2 d) S C 2 1. S 2 2. S 15. (20 points) The ketones shown below can form either of two different enolates, depending on reaction conditions. Draw the expected alkylation product in each case, paying particular attention to the reaction conditions provided. If no temperature is given, assume ambient (room) temperature. a), b) aet, Et C 3 -I 1. LDA, -78 C 2. PhC 2 Ph c) C 2 Et aet, Et C 2 Et 10
d) 1. LDA, -78 C 2. C 3 -I 16. (15 points) Draw the expected organic product from the following reaction. + a (1 equivalent) C 3 C 3 17. (10 points) Show the product of the intramolecular Aldol condensation of 2,5- hexanedione. aet Et 11
18. (10 points) The ketoester below is the product of Dieckmann condensation. Draw the organic starting material that is needed to prepare this ketoester. Et C 2 Et C 2 Et 19. (6 points) The non- bonding ( lone pair ) of electrons on nitrogen is responsible for much of the chemical behavior of amines. The DA nucleotide base adenine is shown below. Draw an arrow to each lone pair of electrons that is available for protonation by a weak acid or for participation in hydrogen bonding. 2 12
20. (10 points) Compound B is more basic than compound A, even though they are both tertiary amines adjacent to an aromatic ring. In the space provided, explain why B would be more basic. A B The lone pair of electrons on in compound B are not in conjugation with the pisystem of the aromatic ring. Therefore they are not tied up in resonance and are more available for protonation. 21. (20 points) Below are several reactions of amines and related compounds. Provide the expected organic product in each case. a) aet, Et a, 2 2 b) 1. LiAl 4 2. 2 13
c) C 3 -I I d) excess 2 Pd/C 2 2 ED F EXAM 14