Midterm Exam Questions for Organic Chemistry II | CH 310N, Exams of Organic Chemistry

Download Midterm Exam Questions for Organic Chemistry II | CH 310N and more Exams Organic Chemistry in PDF only on Docsity! LAST NAME: FIRST NAME: UTEID: Instructions This exam will be closed book. No notes, books, calculators, or molecular models will be allowed. The exam will be comprised of two distinct parts: Part I will consist of a series of multiple choice questions. Your answers to these questions must be submitted on a Scantron “bubble” sheet. The answer sheet will be provided for you, but you will need your own #2 pencil(s). Only answers marked on the bubble sheet will be graded. Answers to Part I questions marked on the exam itself cannot not be graded. No re-grades will be possible on Part I of the exam. Part II consists of questions for which you will need to write out your answers, using structures and/or words. This part of the exam will be hand-graded. Answers for the Part II questions that are written in pencil will not be eligible for re-grades. Answers written in pencil with ink overlay will not be eligible for re-grades. If you use a pen to answer the Part II questions, only blue or black ink is acceptable. Answers written in red ink cannot be graded. 1. You must have your valid UT ID card (or other government-issued ID) with you. You will need to show it to the proctors when you turn in your exam. 2. Chapter 4 of the University’s “General Information” catalog outlines this university’s policies regarding exams, as well as other quizzes administered during the semester. Specifically, students are expected to remain in the exam room until a test is completed. These policies will be strictly enforced, with no exceptions. You may not leave the room for any reason until you are ready to turn in your exam. If you wish to leave the room, you will need to turn in your exam to the proctors, and you will not be allowed to return. Please, plan accordingly by using the rest room before the exam starts. CH 310 N Exam I MWF 11 AM Question Value Score 1 15 2 16 3 12 4 12 5 10 6 10 Section II 75 Section I 75 Raw Total 150 Grade UTID: ________________________ February 2011 1 CH310N-Exam I Version 1 Objective Test Section Identify the choice that best completes the statement or answers the question. There is only one correct answer; please carefully bubble your choice on the scantron sheet. (3pts. ea; 75 pts this section) 1. Which feature in the 1H NMR spectrum provides information about the electronic environment of the protons in a compound? a. splitting b. chemical shift c. integral d. number of signals 2. What is the major organic product obtained from the following sequence of reactions? a. 1 b. 2 c. 3 d. 4 3. Which of the protons in the following molecule appear furthest downfield in the 1H NMR spectrum? a. i b. ii c. iii d. iv 4 10. Which of the following alcohols can be prepared from a Grignard reagent and ethylene oxide? a. only 1 b. only 1 and 2 c. only 1, 2 and 3 d. 1, 2, 3 and 4 11. Which of the protons in the following molecule appear furthest downfield in the 1H NMR spectrum? a. i b. ii c. iii d. iv 12. What is the hydrogen deficiency index for a compound with a molecular formula of C10H16O2? a. 1 b. 2 c. 3 d. 4 13. Which feature in the 1H NMR spectrum provides information about the number of neighboring protons of each proton in the compound? a. integral b. chemical shift c. number of signals d. multiplicity 5 14. Which C8H10 compound gives the following 1H NMR spectrum? a. 1 b. 2 c. 3 d. 4 15. Which combination(s) of alkyl bromide and carbonyl compound can be used to prepare the following product by reaction of the Wittig reagent derived from the alkyl bromide with the carbonyl compound? a. only 1 and 2 b. only 2 and 4 c. only 2 and 3 d. only 1, 2 and 3 6 16. What is required for a bond to give an infrared absorption? a. a change in reduced mass during vibration b. a change in bond angle during vibration c. a change in bond dipole during vibration d. a change in bond length during vibration 17. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 18. Which feature in the 1H NMR spectrum provides information about the number of types of different protons in a compound? a. integral b. number of signals c. splitting d. chemical shift 9 25. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 ID: A 1 CH310N-Exam I version 1 Answer Section MULTIPLE CHOICE 1. ANS: B PTS: 3 2. ANS: A PTS: 3 3. ANS: D PTS: 3 4. ANS: A PTS: 3 5. ANS: C PTS: 3 6. ANS: D PTS: 3 7. ANS: B PTS: 3 8. ANS: A PTS: 3 9. ANS: C PTS: 3 10. ANS: B PTS: 3 11. ANS: C PTS: 3 12. ANS: C PTS: 3 13. ANS: D PTS: 3 14. ANS: A PTS: 3 15. ANS: B PTS: 3 16. ANS: C PTS: 3 17. ANS: B PTS: 3 18. ANS: B PTS: 3 19. ANS: B PTS: 3 20. ANS: A PTS: 3 21. ANS: D PTS: 3 22. ANS: C PTS: 3 23. ANS: D PTS: 3 24. ANS: D PTS: 3 25. ANS: A PTS: 3 CH 310 N EXAM #1 UTEID 10 KEY V 1 PART 2: Free Style Answer Format (75 pts in this section) 1) Reactions: Provide the products for the following reactions. Show any relevant stereo and regiochemistry. (3 pts per structure-n-a-box) MgBr 1) 2) H3O+ 1) 2) H3O+ 1) 2) H3O+ 1) 2) H3O+ 1) 2) H3O+ H3C H O OH H OH CH3 OH CH2CH3 H3C CH2CH3 O H H O O OH CH3 O CH3 OH CH3 (racemic) (racemic) (racemic) CH 310 N EXAM #1 UTEID 13 KEY V 1 5) Unknowns: The spectra of an unknown compound are shown below. Interpret & summarize the key features of each spectrum (in the space provided) and propose a structure. (10 pts for unknown & interpretation) Unknown 1 C6H12O2 MW 116 1H NMR- (Integers indicate relative integration of protons) IR: C—H stretch, aliphatic <3000 cm-1; C=O, 1740 cm-1; C—O 1050cm-1 1HNMR: 3.68, s, 3H; 2.39, multiplet, 1H; 2.21, d, 2H; 0.91, d, 6H Proposed Structure: CH 310 N EXAM #1 UTEID 14 KEY V 1 6) Unknown: The spectra of an unknown compound are shown below. Interpret & summarize the key features of each spectrum (in the space provided) and propose a structure. (10 pts for unknown & interpretation) Unknown 2 C5H11Br MW 150 1H NMR- (Integers indicate relative integration of protons) IR: Aliphatic C—H stretches < 3000 cm-1 1HNMR: 3.42, pentet, 1H; 1.79, multiplet or (d of q), 4 H; 1.05, t, 6H Proposed Structure: Br H END OF EXAM SECTION LAST NAME: FIRST NAME: UTEID: COVER PAGE Instructions This exam will be closed book. No notes, books, calculators, or molecular models will be allowed. The exam will be comprised of two distinct parts: Part I will consist of a series of multiple choice questions. Your answers to these questions must be submitted on a Scantron “bubble” sheet. The answer sheet will be provided for you, but you will need your own #2 pencil(s). Only answers marked on the bubble sheet will be graded. Answers to Part I questions marked on the exam itself cannot not be graded. No re-grades will be possible on Part I of the exam. Part II consists of questions for which you will need to write out your answers, using structures and/or words. This part of the exam will be hand-graded. Answers for the Part II questions that are written in pencil will not be eligible for re-grades. Answers written in pencil with ink overlay will not be eligible for re-grades. If you use a pen to answer the Part II questions, only blue or black ink is acceptable. Answers written in red ink cannot be graded. 1. You must have your valid UT ID card (or other government-issued ID) with you. You will need to show it to the proctors when you turn in your exam. 2. Chapter 4 of the University’s “General Information” catalog outlines this university’s policies regarding exams, as well as other quizzes administered during the semester. Specifically, students are expected to remain in the exam room until a test is completed. These policies will be strictly enforced, with no exceptions. You may not leave the room for any reason until you are ready to turn in your exam. If you wish to leave the room, you will need to turn in your exam to the proctors, and you will not be allowed to return. Please, plan accordingly by using the rest room before the exam starts. CH 310 N Exam 2 MWF 11 AM Question Value Score 1 12 2 12 3 15 4 16 5 10 6 10 Section II 75 Section I 75 Raw Total 150 Grade 3 7. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 8. One advantage of using enamines over enolates, for alkylation reactions, is: a. enamines are resistant to acid b. enamines undergo monoalkylation c. enamines are basic compounds d. enamines convert to ketones 9. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 4 10. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 11. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 12. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 5 13. What is the best choice of reagent(s) to perform the following transformation? a. H2, Pt b. NaH c. 1. NaBH4; 2. H2O d. 1. LiAlH4; 2. H3O+ 14. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 8 22. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 23. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 9 24. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 25. What is the approximate pKa value of acetic acid a. 35 b. 15 c. −2 d. 5 ID: A 1 CH310N-Exam II version 1 Answer Section MULTIPLE CHOICE 1. ANS: C PTS: 3 2. ANS: B PTS: 3 3. ANS: A PTS: 3 4. ANS: C PTS: 3 5. ANS: C PTS: 3 6. ANS: C PTS: 3 7. ANS: C PTS: 3 8. ANS: B PTS: 3 9. ANS: C PTS: 3 10. ANS: A PTS: 3 11. ANS: B PTS: 3 12. ANS: C PTS: 3 13. ANS: C PTS: 3 14. ANS: B PTS: 3 15. ANS: B PTS: 3 16. ANS: C PTS: 3 17. ANS: B PTS: 3 18. ANS: A PTS: 3 19. ANS: C PTS: 3 20. ANS: A PTS: 3 21. ANS: B PTS: 3 22. ANS: A PTS: 3 23. ANS: B PTS: 3 24. ANS: B PTS: 3 25. ANS: D PTS: 3 CH 310 N EXAM #2 UTEID 12 KEY 3) Mechanism: Provide a mechanism for the following transformation. Show all important flows of electrons, charges and intermediates. (15 pts) C O NH2 H C O NH2 H C O NH2 H C O NH2 H OH H C O NH2 H O H C HO NH2 H O HC HO NH3 O HC HO NH3 OC HO NH4 Protonated Amide-must show 3 resonance structures for full credit Water attacks-(use only one of the resonance structures) Intramolecular proton transfer Elimination of ammonia Acid Base reaction to give final products CH 310 N EXAM #2 UTEID 13 KEY 4) Multi-step synthesis: Follow the instructions for each pathway and provide the structure-n- a-box. (16 pts) O CO2CH3 O CO2CH3 O CO2CH3 Br Br O CO2CH3 O CO2CH3 1) NaOH 2) HCl 3) (heat) 1) NaOH 2) HCl 3) (heat) O O CH3 CH3CH3 CH3 CH3 CH3 CH3 What base/conditions are used to make the kinetic enolate? What base/conditions are used to make the thermodynamic enolate? kinetic enolate thermodynamic enolate LDA; low temp NaOMe/MeOH; heat CH 310 N EXAM #2 UTEID 14 KEY 5) Multi-step synthesis: Provide the products in the following linear synthesis. (10 pts) O Br O O OH H2O cat H+ 1) LDA 2) O O PCC O NaOH heat UTID: ________________________ April 2011 1 CH310N-Exam III V 1.0 Objective Test Section Identify the choice that best completes the statement or answers the question. There is only one correct answer; please carefully bubble your choice on the scantron sheet. (3pts. ea; 75 pts this section) 1. What are the relative positions of the substituents in the following structure? a. para b. anti c. ortho d. meta 2. Which of the following undergoes the most rapid acylation upon treatment with acetyl chloride and AlCl3? a. 1,4-dichlorobenzene b. toluene c. benzene d. chlorobenzene 3. Which of the following statements is not true about the structure of benzene? a. six atomic 2p-orbitals overlap to form six π-molecular orbitals b. the bonds alternate in length around the ring c. the ground state electronic configuration of benzene has six electrons in three π-bonding molecular orbitals d. there are three bonding π-molecular orbitals and three π-antibonding molecular orbitals 4. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 2 5. Which of the following heterocycles is not aromatic? a. 1 b. 2 c. 3 d. 4 6. Which of the following molecules is the most acidic? a. 1 b. 2 c. 3 d. 4 7. Which of the following is(are) formed upon addition of 1 mol of Br2 to 1,3-cyclohexane? a. only 2 b. only 1 and 3 c. only 2 and 4 d. 1, 2 and 3 8. Which of the following undergoes the most rapid sulfonation upon treatment with fuming sulfuric acid? a. benzoic acid b. nitrobenzene c. benzene d. benzonitrile 3 9. Which of the following reaction coordinate diagrams explains the formation of different thermodynamic (T) and kinetic products from the same reactants (R)? a. 1 b. 2 c. 3 d. 4 10. What is the IUPAC name of the following compound? a. 2,4-dibromotoluene b. 2,4-dibromohydroxybenzene c. 2,4-dibromophenol d. 4,6-dibromophenol 6 18. Which of the following compounds are tertiary (3°) amines? 1. (CH3)2CHN(CH3)2 2. CH3CH(CH3)N(CH2CH3)2 3. CH3CH2CH2NHCH3 4. CH3CH2CH2CH2CH2NH2 a. 1 and 2 b. 1 and 3 c. 1, 2 and 3 d. 1, 2, 3 and 4 19. What is the reactive intermediate in the reaction of 1,3-butadiene with HBr resulting in 1,2-addition? a. cyclic bromonium cation b. dienophile c. allylic radical d. allylic cation 20. What is the major organic product obtained from the following sequence of reactions? a. 1 b. 2 c. 3 d. 4 7 21. Which of the following does not undergo oxidation in the presence of H2CrO4? a. 1 b. 2 c. 3 d. 4 22. What is the best choice of reagent to achieve the following reaction? a. NaBr b. HBr, H2O c. Br2, light d. Br2, CCl4 23. What is (are) the major organic product(s) formed in the following reaction? a. only 1 b. only 2 c. only 1 and 3 d. only 2 and 4 8 24. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 25. What is the major organic product obtained from the following reaction? a. 1 b. 2 c. 3 d. 4 CH 310 N EXAM #3 UTEID 11 KEY 2) Texas two step: Each of these problems are two step synthesis of a product. In the boxes around the arrows, provide the reagents for the reaction; note that a hydrolysis step (e.g. to finish a Grignard reaction) may be required. In the rounded rectangle, draw the structure of the compound from the first reaction. (2 pts for reagents; 2 pts for structure-n-a-box) CH 310 N EXAM #3 UTEID 12 KEY 3) Resonance: p-nitro phenol and m-nitro phenol are both acidic compounds, but one isomer is more acidic than the other. a) Draw the various resonance structures for each phenoxide anions. b) Predict which isomer is the more acidic and use the resonance structures to support your rationale. (16 pts) Draw the family of resonance structures for the p-nitrophenoxide: O NO2 O NO2 O NO2 O NO2 O N OO O OO NO2 NO2 NO2 This resonance structure show the stabilizing effect of the nitro group at the para position Draw the family of resonance structures for the m-nitrophenoxide: This group of resonance structures shows that the nitro group has less stabilizing influence on the anion and therefore a lesser effect upon the acidity. O N OO pKa (p-nitrophenol)= 7.2 Stronger acid than m isomer pKa (m-nitrophenol)= 8.4 Weaker acid than p isomer CH 310 N EXAM #3 UTEID 13 KEY 4) Mechanism: Provide a mechanism for the following transformation. Show all important flows of electrons, charges and intermediates. Where indicated, (in the structure boxes)- draw the intermediates. (12 pts)