Faculty of Science Mid-Term Examination II. Chem 222/234 Introductory Organic Chemistry I

Transcription

1 Student Name: Student ID #: Faculty of Science Mid-Term Examination II Chem 222/234 Introductory rganic Chemistry I Examiner: Professor James L. Gleason Tuesday, November 10, 2009 Associate Examiner: Professor Dmytro Peripichka 6:30-9:00 PM Instructions: 1. Fill in your student ID number and the first two initials of your name on the SCANTRN CARD. Write your name and student ID number on both TIS SEET and the SCANTRN CARD. 2. This exam has several versions. This is Version 1. Be sure that the correct version is listed on your exam card. 3. The exam booklet contains three sections. Section 1 contains questions from the lectures and has 20 multiple choice questions. Section 2 has 5 lab questions. nly CEM 222 students need to answer this section. Section 3 has three written questions. ANSWER TESE DIRECTLY N TE EXAM PAPER. 4. Molecular model sets are allowed. 5. No notes or textbooks. 6. Both the exam booklet and the exam card must be turned in for a mark to be issued.

2 Section 1. Multiple Choice Questions (4 pts each) 1. What is the product in the following reaction? Na? Cl Cl Cl Cl Cl Cl 2. Which of the following would give a positive iodoform test upon treatment with I 2 and Na? 3 C N C 3 C 3 N N C 3 3. Which molecule is the most acidic? 4. Which statement about keto/enol tautomers is correct? A) For simple ketones, the keto form is more stable B) A β-carbonyl will increase the amount of enol present C) nly acid will catalyze formation of an enol from a ketone D) Two of the above are true. E) A, B, C are all true 2.

3 5. What is the best way to form the alkene shown below? C A Br Ph 3 P nbuli C B Br Ph 3 P nbuli C LDA PhC 2 Br LiAl 4 C D LDA LiAl 4 6. What is the product of the following reaction sequence? N cat. Cl I 2,? N A B C D E: None of the above

4 7. The reaction conditions below will result in: N Dean-Stark A) an aldol reaction B) a Michael addition C) formation of an enamine D) formation of an imine E) no reaction will occur 8. What is the product of the reaction below? Na 9. Which statement about ester hydrolysis is true: A) hydrolysis under acidic conditions is reversible B) the reaction is aided by addition of alcohol C) hydrolysis under basic conditions is reversible D) removal of water using a Dean-Stark trap will push the reaction to completion E) more than one of the above is true 10. Which of the following would not be oxidized by the Jones reagent ( 2 Cr 4 in acetone)?

5 11. Which combination below will result in a good crossed aldol reaction? A Na B Na C Na D Ph Ph Na E None of the above will give a good aldol reaction 12. The formation of an acetal from an aldehyde requires, among other things: A) a diol B) an acid catalyst C) the addition of water D) the formation of an enolate E) none of the above 13. What is the product of the sequence below? 3 Ph 3 P or Zn/Cl

6 14. Which of the following would be oxidized to an aldehyde by PCC in C 2 Cl 2? 15. Which of the following is not stable? 16. What is the product of the reaction shown? LDA Br 17. What is the best way to achieve the following transformation? Me A) 1. Cl, Me; 2. MeMgBr; 3. Cl, 2 B) 1. Na; 2. MeMgBr; 3. Cl, 2 C) MeMgBr D) 1. MeMgBr; 2. Cl, Me; 3. Cl, 2 E) None of the above

7 18. rder the following from most to least acidic. I II III IV A) I > II > III > IV > V B) III > IV > II > V > I C) IV > III > V > II > I D) IV > III > I > II > V E) None of the above Cl N V 19. What is the product of the following reaction sequence? NaB 4 PBr 3 PPh 3 nbuli or NBS, PPh 3 Br 20. What aldol condensation product results when the following ketone is treated with acid?

8 Lab Questions (CEM 222 Students NLY) 21. Why was oxalic acid added to the reaction mixture in the oxidation of cyclohexanol? a) to protonate the product. b) to quench the reaction. c) to deprotonate the product. d) to get rid of excess base. 22. Why was a derivative made of the product of the oxidation of cyclohexanol? a) the yield of the derivative indicated the purity of cyclohexanone. b) It was a simple way of identifying cyclohexanone c) to make the product more volatile d) none of the above 23. A sufficient amount of drying agent has been added to a solvent: a) when the once cloudy solution is clear. b) when the drying agent appears dense and tends to clump at the bottom of the flask. c) when newly added drying agent floats freely when the flask is stirred d) all of the above 24. The Aldol condensation performed in the laboratory: a) was solvent free because it occurred in melted starting material. b) made use of an instant ylide c) proceeded by an S N 1 mechanism. d) none of the above 25. Bumping occurs when large bubbles form when boiling a liquid. Which statement(s) below is true about bumping? a) boileezers, made up of inert porous material, allow the formation of small bubbles. b) boiling chips cannot be added once the liquid is boiling. c) stirring with a magnetic stirring bar can also be used to prevent bumping. d) all of the above

9 Short answer questions. 1. ( 6 pts) Draw a detailed arrow-pushing mechanism and predict the product. Et Cl Esterification. See Solomons page (8 pts) Propose a synthetic route to prepare the alkene shown from benzyl alcohol, 2-propanol and any other reagents you need. You do not need to show mechanisms.

10 3. (6 pts) Draw an arrow pushing mechanism for the iodoform reaction. If a certain step repeats, you do not need to re-draw the mechanism each time. Na I 2 Na See Solomons pgs 740 and 741