Test 2 233 2023

pdf

School

University of British Columbia *

*We aren’t endorsed by this school

Course

233

Subject

Chemistry

Date

Oct 30, 2023

Type

pdf

Pages

Uploaded by LieutenantPrairieDogMaster888

1 THE UNIVERSITY OF BRITISH COLUMBIA Department of Chemistry June 2, 2023 CHEM 233 Test 2 Time Limit: 40 minutes Exam Instructions 1. Check that this examination paper consists of 8 total pages, printed on both sides. 7. You may keep your exam booklet. 2. Answer all questions on the Answer Sheet that accompanies this examination booklet. 8. DO NOT fold the Answer Sheet. 3. The last page of this examination booklet is a periodic table . You may detach this page. 9. Please write clearly on the Answer Sheet so that Gradescope can read your answers. 4. Calculators are not allowed. 5. Molecular model kits are permitted. These kits may also contain pre-built structures. 6. No electronic communication devices are permitted on the desk area when writing. Cell phones must be set to silent and out of reach for the entire writing of the exam. ANY ANSWERS WRITTEN IN THIS EXAMINATION BOOKLET WILL NOT BE GRADED, FOR ANY REASON Rules Governing Formal Examinations 1. Each examination candidate must be prepared to produce, upon the request of the invigilator or examiner, his/her/their UBCcard for identification. ii. Purposely exposing written papers to the view of other examination candidates or imaging devices; 2. Examination candidates are not permitted to ask questions to the examiners or invigilators, except in cases of supposed errors or ambiguities in examination questions, illegible or missing material, or the like. iii. Purposely viewing the examination papers of other candidates; 3. No examination candidate will be permitted to enter the examination room after the expiration of one-half hour from the scheduled starting time, or leave during the first half hour of the examination iv. Using or having visible at the place of writing any books, papers or other memory aid devices other than those authorised by the examiner(s), and; 4. Examination candidates must conduct themselves honestly and in accordance with established rules for a given examination, which will be articulated by the examiner or invigilator prior to the examination commencing. Should dishonest behaviour be observed by the examiner(s) or invigilator(s), pleas of accident or forgetfulness shall not be received. v. Using or operating electronic devices including but not limited to telephones, calculators, computers, or similar devices other than those authorized by the examiner(s) – (electronic devices other than those authorized by the examiner(s) must be completely powered down if present at the place of writing). 5. Examination candidates suspected of any of the following, or any similar practices, may be immediately dismissed from the examination 6. Examination candidates must not destroy or damage any examination material, must hand in all examinations papers, and must not take any examination material from the

2 by the examiner/invigilator, and may be subject to disciplinary action: examination room without permission of the examiner or invigilator. i. Speaking or communicating with other examination candidates, unless otherwise authorized; 7. Examination candidates must follow any additional examination rules or direction communicated by the examiner(s) or invigilator(s).

3 Part 1: Multiple Choice. Questions 1 – 10 should be entered in the Answer Sheet that accompanies this Question Booklet. Nothing in this exam booklet will be graded. In some cases, more than one answer is possible. Do not guess: credit for incorrect answers will be removed from credit for correct answers. Questions are not necessarily equally weighted. 1 . [5 marks] Rank all five molecules below in order of thermodynamic stabilities from least stable to most stable. A . V < W < X < Y < Z B . V < Z < Y < W < X C . X < W < Y < Z < V D . X < Y < Z < W < V E . Y < V < X < W < Z 2 . [6 marks] Choose all the compounds below that can yield an E1 product under normal E1 conditions (concentrated H 2 SO 4 , heat). 3 . (7 marks). Consider compounds A - G for the following question. Choose all the compounds that are aromatic . Questions 4-10 (21 marks): For each question, choose the answer that represents the completed structure in boxes Q4-Q10. V W X Y Z OH CH 3 OH OH OH OH A B C D E F N N O OR N N A B E D F C O G

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version

Access to all documents
Unlimited textbook solutions
24/7 expert homework help

4 question 5: A B C D E F G A B C D E F G A B C D E F G ionization (loss) of O-P 2 O 5 3- carbocation intermediate 1 more significant contributor conformer of carbocation intermediate 1 single bond rotation cyclization carbocation intermediate 2 carbocation intermediate 3 cyclization carotane skeleton (less substituted alkene) E 1 proton loss question 6: question 7: question 8: question 9 and question 10: A B C D E F A B C D E F G H O 3- O 5 P 2 question 4: A B C D E F G Q6 Q8 Q9 Q10 Q4 Q7 Q5

5 Part 2: Short answer questions . Q11-Q17 [40 marks] Predict the major products of the reactions below ( Q11-Q17 ). Draw stereochemistry clearly where appropriate. Do not draw any product twice. 11 . 12 . 13 . 14 . 15 . 16 . 17 . OH EtOH OH H 2 SO 4 (conc.) heat Br CH 3 S – Na THF Solvent Br t-BuO – Na THF Solvent H 2 O H 2 SO 4 (cat.) HBr CH 3 OH H 2 SO 4 (cat.)

6 18 . [21 marks] (a) Draw the compound below in its most stable conformation. (b) Draw the product formed when the above compound is treated with sodium t -butoxide, NaOC(CH 3 ) 3 . A “flat” structure will suffice. (c) Draw the mechanism for the reaction from part (b). Hint : Us the same structure you drew in part (a). (d) Explain why the isomer below is much slower to give the same product formed in part (b) under the same conditions. Use structures as needed. C(CH 3 ) 3 CH 3 Br CH 3 C(CH 3 ) 3 CH 3 Br CH 3

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version