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Final

Exam Spring 2011 V1.pdf

30 Pages
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Department
Chemistry
Course Code
CHEM 2AA3
Professor
Paul Harrison

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Description
CHEM 2OA3 FINAL EXAM June 16, 2011 VERSION 1 NAME (First & Last): ___ _____________ ID#: _______________ Please circle your lab section/E in the table below: Group Thursday Exempt Monday Tuesday Wednesday Thursday Friday AM I L01 L02 L03 L04 L05 L06 E Duration: 3 hours Instructor: Teri Gullon Instructions: This examination paper consists of 30 pages, containing 28 multiple choice (MC) questions, and 8 short-answer questions. A mini-periodic table, spectral correlation charts and scrap paper are provided on the last 4 pages. Feel free to detach these last pages for easier use. Answer all the MC questions on optical scan sheets. Each MC question is worth 1.5 marks and you will not be penalized for incorrect answers. Follow the instructions on the optical scan sheets, and the University rules for OMR exams which are reproduced on page 2. Failure to follow instructions may result in loss of credit. You are responsible for ensuring your copy of the test is complete, no pages are missing, that all answers are in the correct place, and that you follow the correct procedure for filling out the scan sheet. BRING ANY DISCREPANCY TO THE ATTENTION OF YOUR INVIGILATOR. All McMaster rules and procedures relating to Academic Dishonesty and Academic Integrity apply to this exam; all violations will result in a penalty. Students must do their own work. You MUST also complete ALL the information at the top of this page. Failure to do so may result in a loss of marks. Markers Only: Written Section Q1 Q2 Q3 Q4 Q5 Q6 Q7 Q8 /16 /4 /8 /12 /12 /5 /4 /5 MC total = /42 Written Section Total /66 Page 1 Continued on next page OMR EXAMINATION – STUDENT INSTRUCTIONS NOTE: IT IS YOUR RESPONSIBILITY TO ENSURE THAT THE ANSWER SHEET IS PROPERLY COMPLETED. YOUR EXAMINATION RESULT DEPENDS UPON PROPER ATTENTION TO THESE INSTRUCTIONS. The scanner, which reads the sheets, senses the bubble shaded areas by their non- reflection of light. A heavy mark must be made, completely filling the circular bubble, with an HB pencil. Marks made with a pen will NOT be sensed. Erasures must be thorough or the scanner will still sense a mark. Do NOT use correction fluid on the sheets. Do NOT put any unnecessary marks or writing on the sheet. 1. On SIDE 1 (red side) of the form, in the top box, print your student number, name, course name, and the date in the spaces provided, in pen. Then you MUST write your signature, in the space marked SIGNATURE. 2. In the second box, mark your student number and test or exam version number (1, 2, 3 …) by filling in the corresponding bubbles underneath, in pencil. 3. Answers: mark only ONE choice from the alternatives (A,B,C,D,E) provided for each question. The question number is to the left of the bubbles. Make sure that the number of the question on the scan sheet is the same as the number on the test paper. Begin answering Question # 1 using the first set of bubbles, marked “1”. Do Not use Side 2. Page 2 Continued on next page Written Section [Marks in square brackets] 1) [16]Complete the following reactions schemes with the MAJOR product(s) on the right. Include stereochemistry if relevant: OH PCC CH2Cl2 OH NaNH 2 NH3 (l) 1) B3 :THF 2) 2 2 , NaOH2 H O Br NaOCH 3 CH 3H ∆ 1) Ts-Cl OH 2) NaBr, DMSO NaOtBu/HOtBu Br ∆ F NaCN (1 eq) Br DMSO O I ONa DMF Page 3 Continued on next page 2) [4]: Answer the following questions relating to the following mass spectrum: Key Peak Data: m/z Relative intensity % (rescaled so that M+ is 100%) + 188.0 (M ) 100.0 189.0 13.6 190.0 32.5 A) [1] What heteroatom(s) (not C or H) is/are present in the compound? B) [2] What is the molecular formula of the compound? C) [1] When molecules and their fragments are separated in (EI) mass spectrometry, what species are actually detected? (Circle the correct answer) Neutral Species Radical Species Charged Species Page 4 Continued on next page 3) Below is the spectral data for a compound with molecular formula: C H N O 8 10 2 Answer the following questions concerning this compound. IR 1 H NMR ∫3 ∫2 ∫2 ∫2 ∫1 Page 5 Continued on next page 1C NMR A) [1] What is the index of hydrogen deficiency (IHD) for this molecule? B) [1] What two atom stretch is leading to the peak at ~1680 cm in the IR spectrum? C) [1] How many unique carbon environments are present in the molecule? 1 C) [1] Why are the peaks at 4.8ppm and 5.8ppm in the H NMR so broad? F) [4] Draw the structure of the compound in the box below: Page 6 Continued on next page 4) [12] Provide suitable reagents and conditions IN THE GIVEN CHART to complete the reaction equations below. You may need more than one reagent for some of these reactions. Assume the given products are the major products. Ensure the shortest, highest yielding synthesis for each transformation. OH (a) (e) (b) (c) Br (d) (f) (g) O OH + enantiomer OH + enantiomer A) ENTER YOUR ANSWERS IN THE FOLLOWING CHART : (a) (b) (c) (d) (e) (f) (g) Page 7 Continued on next page 5) [12] A) Complete the following scheme with intermediates A through F: Br Br NaOCH 3 HBr HBr HBr, 2 O2 HOCH 3 heat A B KMnO , NaOH 4 (aq) Cl2, 2 O heat + + C D E F B) How are A and B related to each other? (Circle your answer) i) Enantiomers ii) Diastereomers iii) Constitutional Isomers iv) Conformational Isomers C) How are C and D related to each other? (Circle your answer) i) Enantiomers ii) Diastereomers iii) Constitutional Isomers iv) Conformational Isomers Page 8 Continued on next page 6) [5] Draw a complete mechanism for the following reaction and the resulting product(s) in the space provided. Include stereochemistry if relevant. If more than one pathway is possible draw all possibilities: Br 2H O2 Page 9 Continued on next page 7) [4] Show a mechanism for the following reaction (do not show termination steps) Br2 CH 4 CH3Br h ν 8) [5] Outline a synthesis to the following target molecule using only bromo-cyclohexane and propan-2-one as the sources of carbon. Show each step of the synthesis and include any other necessary reagents/conditions. Solvents or reagents may contain carbon as long as they don’t add to the molecule. Target Molecule: Molecules containing carbon to use: Br O Synthesis: Page 10 Continued on next page Multiple Choice Section (Each question worth 1.5 Marks): Answers must be completed on the scantron provided 1. You are asked to test the following molecules for unsaturation, using cold basic permanganate. 1 2 3 4 Rank the molecules in order of largest to smallest amount of permanganate decolorized per millimole of compound. A) 2 > 1 > 4 > 3 B) 3 > 2 > 4 > 1 C) 4 > 1 > 3 > 2 D) 2 > 3 > 4 > 1 E) 2 > 3 > 1 > 4 2. Which of the following is a meso compound? A. (2R,3R)-2,3-Dibromobutane B. (2R,3S)-2,3-Dibromopentane C. (2R,4R)-2,4-Dibromopentane D. (2R,4S)-2,4-Dibromopentane E. (2R,4S)-2,4-Dibromohexane Page 11 Continued on next page 3. Which of the following statements is true? i iii iv ii A) i and ii are enantiomers, while iii and iv are meso compounds B) iii and iv are enantiomers, while i and ii are meso compounds C) i and ii are diastereomers, while iii and iv are enantiomers D) iii and iv are diastereomers, while i and ii are enantiomers E) All four are the same compound 4. The following sentence has the format “Statement 1 BECAUSE Statement 2”. Decide whether statement 1 is true, whether statement 2 is true, and whether the REASONING (the ‘because’ relationship) between them is valid. Statement 1: “Both carbocations and carbon-centered free radicals follow the stability order tertiary > secondary > primary, but the order is REVERSED for carbanions” BECAUSE Statement 2: “Both carbocations and carbon-centered free radicals, being electron-rich, are stabilized by alkyl groups, whereas carbanions, being electron-deficient are destabilized by alkyl groups.” A) Statement 1 and Statement 2 are both correct, and the reasoning is valid B) Statement 1 and Statement 2 are both correct, but the reasoning is NOT valid C) Statement 1 is correct but Statement 2 is NOT correct D) Statement 1 is NOT correct, but Statement 2 is correct E) Statement 1 and Statement 2 are both NOT correct Page 12 Continued on next page 5. You are presented with a sample Y which contains a mixture of products. You run the mixture Y on silica coated TLC plates using hexane as the mobile phase and obtain the following results compared to standards I, II, III and IV: Given the following table that indicates which components (I, II, III or IV) are contained in each of the possible compounds, what is the identity of sample Y? Compound Component Component Component
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