A) I B) II C) III D) IV E) V

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1 Exam Name SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 1) Complete the following reaction and provide a detailed, step-by-step mechanism for the process. 1) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 2) Which of the following is the most stable carbocation? 2) A) I B) II C) III D) IV E) V D 1

2 3) Which of the following alkenes reacts with HCl at the slowest rate? 3) A) B) C) D) E) D SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 4) What is hyperconjugation, and how does it affect carbocation stability? 4) Delocalization of electrons by the overlap of a bond with an empty p orbital is hyperconjugation. This effect occurs only when the interacting orbitals are properly aligned. The more alkyl groups which are substituents of a cationic carbon, the more the cation can be stabilized by the delocalizing hyperconjugation effects. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 5) According to the Hammond Postulate, which of the following is correct? 5) A) The transition state of an exothermic reaction step will be more reactant-like than product-like. B) All transition states are more reactant-like than product-like. C) The transition state of an endothermic reaction step will be more reactant-like than product-like. D) All transition states are more product-like than reactant-like. E) The intermediate of an endothermic reaction step will be more reactant-like than product-like. A 2

3 6) Which of the following compounds will react most rapidly with HCl? 6) A) (E)-5-methyl-2-hexene B) 5-methyl-1-hexene C) 2-methyl-2-hexene D) 4-methyl-1-hexene E) (E)-2-methyl-3-hexene C 7) For an endergonic reaction step, the Hammond postulate allows one to say that. 7) A) the transition state of the step resembles the reactants of the step B) the transition state is precisely symmetric with bond-breaking and bond-forming occurring to the same extent C) the step is rate-determining since it has the smallest E a D) the transition state of the step resembles the products of the step E) the reaction containing this step is overall first order D SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 8) Based on the relative stabilities of the intermediates involved, explain the basis for Markovnikov's rule in the addition of hydrogen halides to alkenes. 8) The rate-determining step in this reaction is the production of a carbocation intermediate. Since this step is endothermic, Hammond's postulate allows one to gauge the relative stabilities of the transition states by comparing the relative stabilities of the carbocation intermediates. The reaction pathway which produces the more substituted carbocation will thus occur more rapidly. 3

4 9) Propose a mechanism for the following reaction: 9) 10) Draw the major organic product generated in the reaction below. 10) 4

5 11) Draw the major organic product generated in the reaction below. 11) 12) Draw the major organic product generated in the reaction below. 12) 13) Draw the major organic product generated in the reaction below. 13) 14) Draw the major organic product generated in the reaction below. 14) 5

6 15) Draw the major organic product generated in the reaction below. 15) 16) Draw the structures of the two alkenes that react with HBr to yield 1-bromo-1-methylcyclopentane as the major organic product. 16) 17) Which is more highly regioselective the addition of HCl to methylenecyclohexane or to 1-methycyclohexene? Explain. 17) Addition to methylenecyclohexane is more highly regioselective. There is a greater difference in the activation energies leading to a primary and tertiary carbocation than in the activation energies leading to a secondary and tertiary carbocation. 18) Provide the major organic product(s) in the reaction below. 18) 6

7 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 19) What is the major product of the following reaction? 19) A) I B) II C) III D) IV E) V C 20) What is the major product from the acid-catalyzed hydration of 2-methyl-2-pentene? 20) A) 2-methyl-1-pentanol B) 2-methyl-2-pentanol C) 2-methylpentane D) 1-methoxypentane E) 2-methyl-3-pentanol B SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 21) Which of the following alkenes would have the smaller heat of hydrogenation? Explain. 21) CH2 CH2 or CH3CH CH2 CH 3 CH CH 2 would have the smaller heat of hydrogenation because the double bond is more stable than that of CH 2 CH 2. The greater stability is due to the fact that the double bond in propane is more alkyl substituted than that of ethene. 7

8 22) Draw the major organic product generated in the reaction below. 22) 23) Draw the major organic product generated in the reaction below. 23) 24) Draw the major organic product generated in the reaction below. 24) 25) Complete the following reaction and provide a detailed, step-by-step mechanism for the process. 25) 8

9 26) Provide the structure of the major organic product of the following reaction. 26) 27) Provide the structure of the major organic product of the following reaction. 27) 28) Provide the major organic product(s) in the reaction below. 28) 9

10 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 29) Which of the following alkenes yield(s) 3-bromo-3-methylpentane as the major product upon addition of HBr? 29) A) III only B) I and II only C) I, II, nad III only D) all of them E) none of them D 30) Which of the following carbocations is likely to rearrange? 30) A) I B) II C) III D) IV E) II and IV E 31) What is the name of the major organic product of the following reaction? 31) A) 2,3-dimethyl-1-butanol B) 3,3-dimethyl-1-butanol C) 2,3-dimethyl-2-butanol D) 3,3-dimethyl-2-butanol E) 4-methyl-2-pentanol C 10

11 SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 32) Provide the major organic product(s) in the reaction below. 32) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 33) What is the major product of the following reaction? 33) A) I B) II C) III D) IV E) V B 11

12 34) Which reaction intermediate is formed when Br2/CCl4 reacts with cyclohexene? 34) A) I B) II C) III D) IV E) V D SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 35) Draw the major organic product generated in the reaction below. 35) 36) Draw the major organic product generated in the reaction below. 36) 12

13 37) Complete the following reaction and provide a detailed, step-by-step mechanism for the process. 37) 38) Provide a detailed, step-by-step mechanism for the reaction shown below. 38) 39) Draw the structure of the major product of the reaction below. 39) 13

14 40) Provide the major organic product(s) in the reaction below. 40) 41) Provide the major organic product(s) in the reaction below. 41) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 42) Which of the following is the best reaction sequence to use if one wants to accomplish a Markovnikov addition of water to an alkene with minimal skeletal rearrangement? A) water + dilute acid B) oxymercuration-demercuration C) water + concentrated acid D) hydroboration-oxidation E) none of the above 42) B SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 43) Provide the major organic product(s) in the reaction below. 43) 14

15 44) Draw the major organic product generated in the reaction below. 44) 45) Draw the major organic product generated in the reaction below. 45) 46) Provide the structure of the major organic product of the following reaction. 46) 15

16 47) Provide the structure of the major organic product of the following reaction. 47) 48) Provide the major organic product(s) in the reaction below. 48) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 49) What reagents are needed to accomplish the following transformation? 49) A) H2O/Peroxide B) OH- C) BH3 D) 1. BH3/ 2. HO-, H2O2, H2O E) H2O/H+ D 16

17 50) What reagents can best be used to accomplish the following transformation? 50) A) 1. BH 3 THF 2. HO -, H 2 O 2 B) NaOH, H 2 O C) H +, H 2 O D) 1. Hg(O 2 CCF3) 2, CH3OH 2. NaBH 4 E) 1. Hg(OAc) 2, H 2 O/THF 2. NaBH 4 A SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 51) Draw the major organic product generated in the reaction below. 51) 52) Draw the major organic product generated in the reaction below. 52) 17

18 53) Provide the major organic product(s) in the reaction below. 53) MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 54) Which of the following reagents gives the reaction shown below? 54) CH3CH= CH2 +? CH3CH2CH3 A) H2/Ni B) H2O/Ni C) H2O/H2SO4 D) H2/H2SO4 E) H2/HCl A 18

19 55) Which of the following is the most stable alkene? 55) A) B) C) D) E) B 56) Upon hydrogenation, which of the following alkenes releases the least heat per mole? 56) A) (Z)-3,4-dimethyl-3-hexene B) (E)-3,4-dimethyl-2-hexene C) (Z)-3,4-dimethyl-2-hexene D) 3,4-dimethyl-1-hexene E) (E)-3,4-dimethyl-3-hexene E SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question. 57) Provide the major organic product(s) in the reaction below. 57) 19

20 58) Complete the following tree of reactions by giving the major products: 58) 20