CHE 322 Summer 2012 Final Exam Form Choose the lowest unoccupied molecular orbital (LUMO) of the pentadienyl cation.

Transcription

1 Multiple Choice Questions: 100 points 1. Choose the lowest unoccupied molecular orbital (LUMO) of the pentadienyl cation. 2. Select the possible reactants of the following reaction. A i B ii C iii D i + ii E i + iii F ii + iii 3. Choose the major product of the following reaction sequence. Page 1

2 4. Choose the order that has the following carbocations correctly arranged with respect to increasing stability. 2 point partial credit for choice C 5. Choose the best synthetic route for making the following diketone from the following keto ester. 3 point partial credit for choices C and F. 2 point partial credit for choice D. Page 2

3 6. Select the correct diene and dienophile to accomplish the following Diels-Alder reaction. A i + iv B i + v C ii + iv D ii + v E iii + iv F iii + v 2 point partial credit for choice B 7. Select the worst method to produce the following ester. 8. Select the aldohexose that has configuration at the anomeric carbon. Page 3

4 9. The following is a synthesis of a 2-O-methyl-aldohexose from a 1-O-methyl-aldohexose. Choose the best 1-O-methyl-aldohexose reactant for the following synthesis. 2 point partial credit for choice D 10. Select the method(s) that produce(s) 3-pentanone as the major product. A i B ii C i + ii D i + iii E ii + iii F all Page 4

5 11. Determine and select the name of monosaccharide A based on the following information. Oxidation of A or C will give the same alderic acid (B). Ruff degradation of C will give the aldopentose shown below. A. D-ribose B. D-allose C. D-talose D. D-gulose E. D-mannose F. D-altrose 12. Choose the best synthetic route for making 4-butyl-2-chloro-1-ethylbenzene from benzene. 2 point partial credit for choices A and D Page 5

6 13. Choose the correct product(s) of the following hemiacetal formation, which utilizes radiolabeling. A i B ii C iii D i + ii E i + iii F ii + iii 14. Choose the major product of the following reaction. 15. Choose the C-4 epimer of L-xylose. 2 point partial credit for choices A and C Page 6

7 16. Select the worst method to produce the following amine. 17. Select the major product of the following reaction. Page 7

8 18. Choose the order that has the following compounds correctly arranged with respect to increasing stability. 2 point partial credit for choice B 19. The following step is part of the mechanism of a ring-expansion reaction. Select the correct intermediate formed by this step. Page 8

9 20. Select the major product of the following reaction sequence. 2 point partial credit for choice B Short Answer Questions: 80 points 21. Give the structure of the reactant of the following reaction. 6 pts 22. Give the structure of the major product of the following reaction. 6 pts Page 9

10 23. Give the structure of the major product of the following reaction. 6 pts 24. Although the Wittig reaction was not specifically discussed with carbohydrates, use your knowledge from both topics to predict and draw the structure of the major product of the following reaction. 8 pts 25. Give the structure of compounds X and Y, based on the synthesis below. 8 pts Error on exam (incorrect molecular formula given). If structure Y was correct, full credit given regardless of structure X. If structure Y was incorrect, then partial credit given was generous. 26. Draw the following ketose in its cyclic form. Use a Haworth projection to show the relative orientation of substituents at each carbon atom of the ring. 6 pts Page 10

11 27. Deduce the structure of the unknown disaccharide Z from the following information, and draw its structure, clearly showing all stereochemistry where appropriate. 10 pts a) Z is a reducing sugar that undergoes mutarotation and forms a phenylosazone. b) Acid hydrolysis of Z yields D-talose and D-glucose. c) Z is hydrolyzed by -talosidase but not by -talosidase, -glucosidase or -glucosidase enzymes. d) Methylation, followed by hydrolysis of Z gives 2,3,4,6-tetra-O-methyl-D-talose and 2,3,4- tri-o-methyl-d-glucose. 28. Propose a synthesis of the following compound starting from any compound(s) containing three carbon atoms or less. 10 pts Page 11

12 29. Using the curved arrow formalism, show all the bond making and bond breaking steps of the following reaction. 10 pts 30. Propose a synthesis of the following compound starting from benzene and any compound(s) containing three carbon atoms or less. 10 pts Page 12