Name: Student Number: University of Manitoba - Department of Chemistry CHEM Introductory Organic Chemistry II - Term Test 1

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1 Name: Student Number: University of Manitoba - Department of Chemistry CHEM Introductory Organic Chemistry II - Term Test 1 Thursday, February 11, 2016; 7-9 PM This is a 2-hour test, marked out of 50 points total. Part marks are available on all questions. Put all answers in the spaces provided. If more space is required you may use the backs of the exam pages but be sure to indicate that you have done so. A spectroscopic data sheet is attached at the end of the exam. QUESTION 1. Mechanism (4 Marks) 2. Mechanism (4 Marks) 3. Mechanism (6 Marks) 4. Mechanism (6 Marks) 5. Reactions and Products (24 Marks) 6. Spectra and Structures (6 Marks) TOTAL (50 Marks) MARKS

2 CHEM 2220 Test #1 Page 2 of 10 Feb 11, (4 MARKS) Provide a stepwise mechanism for the following reaction. 2. (4 MARKS) Briefly explain why the diene shown does not participate in Diels-Alder reactions, even with very good dienophiles.

3 CHEM 2220 Test #1 Page 3 of 10 Feb 11, (6 MARKS) The following process obviously involves some substantial structural rearrangement! Provide a stepwise mechanism to explain the outcome of this reaction. Briefly explain why this process is energetically favorable at each stage.

4 CHEM 2220 Test #1 Page 4 of 10 Feb 11, (6 MARKS) The alkyl halide shown below does not react as one might expect under either of the two sets of conditions shown. a. What type of reaction would be expected to occur under the conditions labelled A? Briefly explain why this reaction does not occur in this particular case. A structural drawing might be helpful in your response. b. What type of reaction would be expected to occur under the conditions labelled B? Briefly explain why this reaction does not occur in this particular case. A structural drawing might be helpful in your response.

5 CHEM 2220 Test #1 Page 5 of 10 Feb 11, (24 MARKS) Provide the necessary reagents/solvents or starting materials or major products to correctly complete the following reactions. Mechanisms are NOT required. Show relative product stereochemistry (wedge and dash bonds) where appropriate if a racemic product is formed, simply indicate +/ or racemic. a. (2 Marks) b. (2 Marks) c. (2 Marks) d. (2 Marks) e. Marks) (2

6 CHEM 2220 Test #1 Page 6 of 10 Feb 11, 2016 f. (2 Marks) g. (2 Marks) h. (5 Marks)

7 CHEM 2220 Test #1 Page 7 of 10 Feb 11, 2016 i. (5 Marks)

8 CHEM 2220 Test #1 Page 8 of 10 Feb 11, (6 MARKS Total) The IR and NMR spectra of an unknown organic compound A having the formula C8H14O are shown on the next page. Based on these data, answer the following questions about compound A. j. (1 Mark) What is the degree of unsaturation in compound A? k. (2 Marks) There are two functional groups in A. What are they? What specific spectroscopic evidence identifies each one? l. (1 Mark) What can be deduced about the structure from the number of unique 13 C NMR signals observed? m. (1 Mark) The signal at ca. 5 ppm integrates for 1 proton. What kind of proton is this, and what structural conclusion can you draw from the fact that it accounts for only 1 H? n. (1 Mark) What is the structure of compound A?

9 CHEM 2220 Test #1 Page 9 of 10 Feb 11, 2016 IR C8H14O 13 C NMR C8H14O 1 H NMR C8H14O s, 3H NB: these are two separate signals! s, 3H m, 1H tr, m, s, 2H 2H 3H

10 Page 10 of 10 Spectroscopy Crib Sheet for CHEM 2220 Introductory Organic Chemistry II 1 H NMR Typical Chemical Shift Ranges Type of Proton Chemical Shift (δ) Type of Proton Chemical Shift (δ) C CH C C H C CH 2 C C C C H C C H O H O OH C OH (solvent dependent) (solvent dependent) O O C H H Aryl C H Cl C H H Br C H Aryl H I C H RCO 2 H Aromatic, heteroaromatic X C H X = O, N, S, halide R 3 C H Aliphatic, alicyclic Y = O, NR, S Y H H Y H Y = O, NR, S Low Field 13 C NMR Typical Chemical Shift Ranges High Field Ester IR Typical Functional Group Absorption Bands CH x -Y Alkene Y = O, N Aryl Ketone, Aldehyde Amide Acid RC N CR 3 -CH 2 -CR 3 CH x -C=O RC CR CH 3 -CR 3 Group Frequency (cm -1 ) Intensity Group Frequency (cm -1 ) Intensity C H Medium RO H Strong, broad C=C H Medium C O Strong C=C Medium C=O Strong C C H Strong R2N H Medium, broad R C C R Medium (R R ) C N 1230, 1030 Medium Aryl H Medium C N Medium Aryl C=C 1600, 1500 Strong RNO Strong

11 ANSWER KEY University of Manitoba - Department of Chemistry CHEM Introductory Organic Chemistry II - Term Test 1 Thursday, February 11, 2016; 7-9 PM This is a 2-hour test, marked out of 50 points total. Part marks are available on all questions. Put all answers in the spaces provided. If more space is required you may use the backs of the exam pages but be sure to indicate that you have done so. A spectroscopic data sheet is attached at the end of the exam. QUESTION 1. Mechanism (4 Marks) 2. Mechanism (4 Marks) 3. Mechanism (6 Marks) 4. Mechanism (6 Marks) 5. Reactions and Products (24 Marks) 6. Spectra and Structures (6 Marks) TOTAL (50 Marks) MARKS

12 CHEM 2220 Test #1 Page 2 of 10 Feb 11, (4 MARKS) Provide a stepwise mechanism for the following reaction. 2. (4 MARKS) Briefly explain why the diene shown does not participate in Diels-Alder reactions, even with very good dienophiles. The diene must be able to adopt an s-cis conformation but in this case the pairs of CH3 groups will be in an impossible steric conflict if that were to happen. Thus, no s-cis and no Diels-Alder.

13 CHEM 2220 Test #1 Page 3 of 10 Feb 11, (6 MARKS) The following process obviously involves some substantial structural rearrangement! Provide a stepwise mechanism to explain the outcome of this reaction. Briefly explain why this process is energetically favorable at each stage.

14 CHEM 2220 Test #1 Page 4 of 10 Feb 11, (6 MARKS) The alkyl halide shown below does not react as one might expect under either of the two sets of conditions shown. a. What type of reaction would be expected to occur under the conditions labelled A? Briefly explain why this reaction does not occur in this particular case. A structural drawing might be helpful in your response. Hydroxide is a strong base and a good nucleophile. Ethanol is not an ionizing solvent. Thus, either SN2 or E2 is potentially possible, but since the temperature is relatively high, we would expect E2 elimination under these conditions. b. What type of reaction would be expected to occur under the conditions labelled B? Briefly explain why this reaction does not occur in this particular case. A structural drawing might be helpful in your response. The HS- anion is a good nucleophile but is not a good base. Also note the low temperature which favours substitution over elimination. We would therefore expect either SN1 or SN2 substitution. Pure ethanol is not especially good at stabilizing ions, which would likely favour SN2. On the other hand, the chloride is tertiary and is unlikely to react by an SN2 mechanism, and the bicyclic structure blocks backside attack in any case. Thus, no substitution occurs.

15 CHEM 2220 Test #1 Page 5 of 10 Feb 11, (24 MARKS) Provide the necessary reagents/solvents or starting materials or major products to correctly complete the following reactions. Mechanisms are NOT required. Show relative product stereochemistry (wedge and dash bonds) where appropriate if a racemic product is formed, simply indicate +/ or racemic. a. (2 Marks) b. (2 Marks) c. (2 Marks) d. (2 Marks)

16 CHEM 2220 Test #1 Page 6 of 10 Feb 11, 2016 e. Marks) (2 f. (2 Marks) g. (2 Marks)

17 CHEM 2220 Test #1 Page 7 of 10 Feb 11, 2016 h. (5 Marks) i. (5 Marks)

18 CHEM 2220 Test #1 Page 8 of 10 Feb 11, (6 MARKS Total) The IR and NMR spectra of an unknown organic compound A having the formula C8H14O are shown on the next page. Based on these data, answer the following questions about compound A. j. (1 Mark) What is the degree of unsaturation in compound A? C8H14O = 2 degrees of unsaturation k. (2 Marks) There are two functional groups in A. What are they? What specific spectroscopic evidence identifies each one? Ketone: IR strong band ~1720 cm -1 and 13 C ~210 ppm but no 1 H ~ ppm so not aldehyde. Alkene: 13 C ~123 and ~133 ppm. l. (1 Mark) What can be deduced about the structure from the number of unique 13 C NMR signals observed? There are 8 unique 13 C NMR signals and 8 carbons in the molecule so there is no symmetry in the structure. m. (1 Mark) The signal at ca. 5 ppm integrates for 1 proton. What kind of proton is this, and what structural conclusion can you draw from the fact that it accounts for only 1 H? The 1 H NMR signal at ~5 ppm is a vinylic proton (i.e. a proton attached to an alkene). Because it integrates for only 1 H, this means that the other 3 positions on the alkene must have carbons attached to them (since there are a total of 4 positions on any alkene that can carry H or substituents). n. (1 Mark) What is the structure of compound A?

19 CHEM 2220 Test #1 Page 9 of 10 Feb 11, 2016 IR C8H14O 13 C NMR C8H14O NB: these are two separate signals! s, 3H s, 3H m, 1H tr, m, s, 2H 2H 3H

Name: Student Number: University of Manitoba - Department of Chemistry CHEM Introductory Organic Chemistry II - Term Test 1

Name: Student Number: University of Manitoba - Department of Chemistry CHEM 2220 - Introductory Organic Chemistry II - Term Test 1 Thursday, February 12, 2015; 7-9 PM This is a 2-hour test, marked out