Chemistry 39. Exam 3

Transcription

1 Chemistry 39 Exam 3 Wednesday, April 0, 005 Name (printed) 6:30-7:45 p.m. S.S. # Signature Please show your picture I.D. to a proctor when you hand in your exam. TTAL 1

2 There are 5 questions on this exam. Check that you have done all of the problems and filled in the first 5 bubbles on the scantron. All questions are worth 4 points. The maximum score on this exam is 100 points. Instructions Answer sheet 1) n the scantron, you need to clearly fill: your name and your student number, section number (Section, 10:10 am) Exam policy ) Use a # pencil 1) Molecular models are allowed, calculators are not allowed. ) The back of the test can be used for scratch paper. 3) Relevant tables, including the periodic table, are attached at the end of this exam. 4) Numerical values given in one question apply only to this question, and should not be used in other questions, unless there is a specific instruction to do so. If necessary, the values from the provided tables should be used, even if they differ from values that you may remember from different sources. 5) You can take the copy of the examine away ints 1) As you read the question, underline or circle key words to highlight them for yourself. ) Questions have only one acceptable answer. No partial credit will be given. 3) There is no penalty for guessing

3 1. Which two components can be condensed, in the presence of the appropriate base, to prepare the compound directly below? a) b) C 3 c) d). Which Michael acceptor will condense with -methyl-1,3-cyclohexanedione (in the presence of sodium ethoxide/ethanol) to yield the product of the Robinson annulation a) b) c) d) 3

4 3. Rank the acidity from most acidic-to-least acidic based upon the acidity of the underlined proton. 1 3 NMe a) 1> >3 b) 1> 3 > c) 3> >1 d) > 1 >3 4. Calculate the equilibrium constant for the reaction using the pka values provided. - Keq - pka = 9 pka = 0 a) b ) c) 10-9 d) Which product (A - D) will result from the Diekman cyclization. 1) cat. NaEt Et Et ) CEt CEt CEt CEt a) b) CEt c) d) CEt 6. Which product (A - D) will result from the following sequence? N 3 3 a) b) c) d) 4

5 7. Consider the reaction below to answer the following questions: the strongest base in the reaction is: - Li -N N A B C D pka = 16 pka = Consider the reaction below to answer the following questions: the weakest acid in the reaction is: - Li -N N A B C D pka = 16 pka = Consider the reaction below to answer the following questions: the enolate ion in the reaction is: - Li -N N A B C D pka = 16 pka = Consider the reaction below to answer the question: NaEt Et This reaction is an example of: a) an intramolecular Claisen condensation b) an intramolecular aldol condensation c) a Robinson annulation d) a Michael reaction 11. Which of the indicated hydrogens is the most acidic? 5

6 (a) (b) Et (d) (c) 1-13 (4 pts each) Select the appropriate starting material (SM) that would afford the indicated product. 1) Na, Br 15. SM ) N N 16. SM heat a) Br b) CN c) CN 3 N d) 14. Give the desired product of the Robinson annulation reaction? C Et NaEt CEt CEt a) CEt b) c) d) CEt 15. Pick up the strongest base from following arylamines? 6

7 a) N Me N b) N c) EtC N d) N N 16. Predict the product of the following sequence of reactions: CEt 1) NaEt ) Et Et Et a) b) c) d) 17. Which reagent is the best for the following transformation? Et Ac N 3 reagent N a) NaB 4 b) LiAl 4 c) NaB 3 (CN) d) Na 18. What is the product of the following reaction? Et 1) NaEt a) b) c) Et Et Et d) Et 19. What is the product of the following reaction? NaEt a) b) c) d) 7

8 0. Robinson annulation is the combination of three processes, which process is not in the Robinson annulation? a) Michael reaction b) Claisen condensation c) Aldol reaction d) dehydration 1. (4 pts) Which of the following sugars when oxidized with N 3 would yield the same aldaric acid? C C C C C C C C I II III IV a) I and II b) I and III c) I and IV d) II and IV. (4 pts) The following structure is that of gulose (Do not assume that it is a naturally occurring sugar). What is the correct description of this sugar? C a) α-d-pyranose b) α-l-pyranose c) β-d-pyranose d) β-l-pyranose 3-5 (4 pts each) Select the appropriate starting material (SM) that would afford the indicated product. 8

9 1) NK 3. Starting Material N ) Na/ 1) LiAl4, ether N 4. Starting Material ) 1) NaCNB3 N 5 Starting Material ) N3/ a) Br b) c) N d) CN 9

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