timer Asked: Apr 30th, 2020

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i will attach the exam, please answer all the questions with the right answers, thank you

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CHEM 2720 EXAM 3 Spring 2020 Name: ____________________ IMPORTANT: PLEASE READ THIS FIRST  Test time: 2 hours from the time you receive it plus 15 min to submit it. Please use your time wisely.  You may use a cheat sheet but are not allowed to consult any other person or any other resource during the test.  You are still required to adhere to academic integrity while taking this online exam. Any type of plagiarism could result in cancellation of your exam and necessary actions. Bonus Questions: 1. Identify the nucleophile and electrophile in the reaction below and label them. O O + H Cl + H + Cl- 2. Add curved arrows to the above reaction to indicate the flow of electrons. 3. Hydrogenation is the process of___________________. 4. Which functional group is present in the following molecule? 5. In nucleophilic substitution reactions with alkyl halides, the leaving group is___________. 1. (6 pts) Calculate the degree of unsaturation for the following compounds. Show calculations for credit. a) C12H8Cl6O b) C16H13N2OCl 2. (6 pts) Draw structures corresponding to each name below. Either condensed or line structures may be used. a. 3,6-dimethyl-1,4-cyclohexadiene b. trans-4,4-dimethyl-2-pentene 3. (9 pts) Provide names for each structure below. Be sure to include the cis, trans or E, Z designations wherever applicable. CH3 CH3C CCHCH2CH2CH3 4. (5 pts) Circle the most stable alkene in the set of isomers below. Briefly explain your choice. 5. (6 pts) Rank the carbocations below in order of increasing stability (least stable = 1; most stable = 3). Place the number corresponding to the carbocation’s relative stability in the blank below the structure. + + + 6. (6 pts) The compound below has been isolated from the safflower plant. Consider its structure to answer the following questions. H H C H3C C C C C C C C H H C C H C C H H a. What is the molecular formula for this natural product? b. What is the degree of unsaturation for this compound? c. Assign E or Z configuration to each of the double bonds in the compound. 7. (3 pts) Ozonolysis of an alkene followed by reduction with dimethyl sulfide gave the following two products. Determine the structure of the starting alkene. 8. (9 pts) Consider the hydroboration of following alkene: H CH3 OH 1. BH3, THF 2. H2O2, NaOH, H2O CH3 H Hydroboration of alkenes is an example of: a. b. c. d. a rearrangement reaction. a substitution reaction. an elimination reaction. an addition reaction. Hydroboration/oxidation of alkenes occurs with: a. b. c. d. anti stereochemistry. trans stereochemistry. syn stereochemistry. unpredictable stereochemistry. The regiochemistry of hydroboration/oxidation of alkenes is: a. b. c. d. Markovnikov. anti-Markovnikov subject to solvent effects. unrelated to alkene structure. 9. (16 pts) Provide the major product, reagent or starting compound in the following reactions: HCl ether 10. (8 pts) Using the following alkyne and a suitable alkyl halide as starting materials, synthesize the following ketone shown on the right. More than one step may be required. Show all reagents and all intermediate compounds in your synthetic scheme. OH CH3CH2C C H CH3CH2CHCH2CH2CH3 11. (6 pts) Select the best reagent or sequence of reagents from the list provided which would best accomplish each transformation below. Place the letter corresponding to the reagent(s) in the blank to the left of each reaction. Each transformation requires only one answer. a. H2SO4, H2O, HgSO4 e. 1. Br2, CCl4 b. H2, Lindlar‘s catalyst 2. 2 NaNH2, NH3 c. 1. BH3, THF f. 1. HCl 2. H2O2 2. NaNH2, NH3 d. 1. NaNH2, NH3 g. Li/NH3 2. CH3CH2I h. 1. NaNH2, NH3 2. CH3CH2CH2I H3C CH3C H C CCH3 H C CH3 O H C CH2 C C H CH CH2 CH3CH2CH2C C CH3 C H 12. (10 pts) Draw the keto form of the following enol and then show the mechanism of ketoenol conversion under acidic conditions. Show all intermediate structures and all electron flow with arrows. 13. (10 pts) Draw all likely products of the following reaction and circle the product you expect to predominate. Propose a stepwise mechanism for the major product formed only. From Exam 2: (10 pts) Consider the reaction below to answer the following questions 40% H3C OH H2O ethanol H3C + Cl 60% HO CH3 Write the complete stepwise mechanism for this reaction. Clearly show the formation of both products. Show all electron flow with arrows AND draw all intermediate structures. ...
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