Organic Chemistry, 7e (Wade) Chapter 8 Reactions of Alkenes 1) HBr can be added to an alkene in the presence of peroxides (ROOR). What function does the peroxide serve in this reaction? A) nucleophile B) electrophile C) radical chain initiator D) acid catalyst E) solvent Answer: C Diff: 2 Section: 8.3 2) Predict the major product of the following reaction.
A) B) C) D) Answer: B Diff: 2 Section: 8.3
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3) Provide the structure of the major organic product of the reaction below.
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Diff: 1 Section: 8.3 4) Name the major product which results when HBr is added to 3-ethyl-3-hexene. Answer: 3-bromo-3-ethylhexane Diff: 2 Section: 8.3 5) Provide the structure of the major organic product of the reaction below.
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Diff: 2 Section: 8.3
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6) Provide the major organic product of the reaction below.
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Diff: 2 Section: 8.3 7) Provide the structure of the major organic product of the reaction below.
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Diff: 3 Section: 8.3 8) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.3 3
9) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.3 10) When 3,6-dimethylcyclohexene is reacted with dry gaseous HBr, one of the products is 1bromo-1,4-dimethylcyclohexane. Provide a detailed step-by-step mechanism to explain the formation of this product Answer:
Diff: 3 Section: 8.3 11) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 1 Section: 8.3
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12) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 1 Section: 8.3 13) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.3 14) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.3 15) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.3 5
16) Complete the following reaction and provide a detailed, step-by-step mechanism for the process.
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Diff: 2 Section: 8.3 17) Based on the relative stabilities of the intermediates involved, explain the basis for Markovinkov's rule in the addition of hydrogen halides to alkenes. Answer: 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 stabilites 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. Diff: 2 Section: 8.3 18) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.3 19) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.3
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20) The following reaction is known to proceed by a free radical chain mechanism. Suggest a reasonable, step-by-step mechanism for this reaction. CH3CH=CH2 + CHCl3 ROOR Answer: RO–OR → 2 RO∙
CH3CH2CH2CCl3
RO∙ + H–CCl3 → RO–H + ∙CCl3 Cl3C∙ + CH2=CHCH3 → Cl3C–CH2– C HCH3
Cl3C–CH2– C HCH3 + H–CCl3 → Cl3C–CH2–CH2CH3 + ∙CCl3 Diff: 3 Section: 8.3 21) Explain the regioselectivity observed in the radical addition of HBr to 2-methylpropene. Answer: The reaction proceeds via the addition of Br∙ to the alkene. Two competing pathways are possible, but the transition state leading to the more substituted alkyl radical is lower in energy. This process ultimately makes the addition anti-Markovnikov in nature. Diff: 3 Section: 8.3 22) Which of the following intermediates is thought to occur in the mechanism by which alkenes are hydrated in the presence of acid? A) carbanion B) carbocation C) free radical D) carbene E) alkyne Answer: B Diff: 2 Section: 8.4
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23) Acid catalyzed hydration (H2SO4/water/△) of an unknown compound (A)with a chemical formula C6H12, yielded a racemic mixture of product C6H13OH. Which, if any, of the following compounds is/are possible structures for the initial compound (A)?
A) compound 1 only B) compounds 2 and 3 C) compound 2 only D) compounds 1 and 3 E) none of the above Answer: E Diff: 2 Section: 8.4 24) The mechanism for the acid-catalyzed hydration of alkenes is simply the reverse of the mechanism by which alcohols are dehydrated using concentrated acid. This is an illustration of the principle of __________. Answer: microscopic reversibility Diff: 1 Section: 8.4 25) Name the major alcohol product which results when 3,3-dimethylbut-1-ene is treated with dilute acid. Answer: 2,3-dimethyl-2-butanol Diff: 2 Section: 8.4
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26) Provide the structure of the major organic product of the reaction below.
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Diff: 3 Section: 8.4 27) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.4
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28) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.4 29) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 1 Section: 8.4 30) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.4
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31) Complete the following reaction and provide a detailed, step-by-step mechanism for the process.
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Diff: 2 Section: 8.4 32) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
Answer: Diff: 3 Section: 8.4 33) Provide the reagents necessary to complete the following transformation.
Answer: 1. Br2, hν 2. H2O, Δ or 1. Br2, hν 2. NaOCH3, CH3OH 3. H3O+ or Hg(OAc)2, H2O; NaBH4 Diff: 3 Section: 8.4
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34) 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) water + concentrated acid C) oxymercuration-demercuration D) hydroboration-oxidation E) none of the above Answer: C Diff: 1 Section: 8.5 35) What synthetic goal is achieved by subjecting an alkene to an oxymercuration-demercuration sequence? A) Markovnikov addition of H2O wherein skeletal rearrangement is promoted B) Markovnikov addition of H2O wherein skeletal rearrangement is prevented C) anti-Markovnikov addition of H2O wherein skeletal rearrangement is promoted D) anti-Markovnikov addition of H2O wherein skeletal rearrangement is prevented E) syn-hydroxylation Answer: B Diff: 2 Section: 8.5 36) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.5
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37) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.5 38) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.5 39) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.5
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40) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.5 41) When an alkene is subjected to treatment with Hg(OAc)2 in alcohol followed by reaction with NaBH4, what new class of compound is formed? A) ether B) epoxide C) alkane D) syn diol E) alkyne Answer: A Diff: 2 Section: 8.6 42) Provide the structure of the major organic product of the reaction below.
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Diff: 2 Section: 8.6
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43) Provide the reagents necessary to convert 3-methyl-2-butanol to 2-methyl-2-butanol. Answer: 1. conc. H2SO4 2. H3O+ or Hg(OAc)2, H2O or 1. PBr3 2. NaOCH3, CH3OH 3. NaBH4 Diff: 2 Section: 8.6 44) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
Answer: Diff: 3 Section: 8.6 45) Treatment of 2-methylpropene with which of the following reaction conditions results in an anti-Markovnikov addition product? A) dry gaseous HBr with peroxides present B) BH3-THF, followed by alkaline H2O2 C) aqueous Hg(OAc)2, followed by alkaline NaBH4 D) dilute H2SO4 and heat E) both A and B Answer: E Diff: 1 Section: 8.7 46) Both (E)- and (Z)-hex-3-ene can be subjected to a hydroboration-oxidation sequence. How are the products from these two reactions related to each other? A) The (E)- and (Z)-isomers generate the same products but in differing amounts. B) The (E)- and (Z)-isomers generate the same products in exactly the same amounts. C) The products of the two isomers are related as constitutional isomers. D) The products of the two isomers are related as diastereomers. E) The products of the two isomers are not structurally related. Answer: B Diff: 2 Section: 8.7
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47) Complete the following reaction by filling in the appropriate reagents.
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Diff: 2 Section: 8.7 48) Provide the structure of the major organic product of the reaction below.
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Diff: 2 Section: 8.7 49) Provide the structure of the major organic product of the reaction below.
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Diff: 2 Section: 8.7
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50) Provide the structure of the major organic product of the reaction below.
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Diff: 3 Section: 8.7 51) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.7 52) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.7
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53) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.7 54) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail. ( Z )-3-hexene
1. BH3 THF 2. H 2O 2 , -OH
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Diff: 3 Section: 8.7 55) Which of the following additions to alkenes occur(s) specifically in an anti fashion? A) hydroboration-oxidation B) addition of Br2 C) addition of H2 D) addition of H2O in dilute acid E) both A and B Answer: B Diff: 1 Section: 8.8 56) Addition of Br2 to (E)-hex-3-ene produces __________. A) a meso dibromide B) a mixture of enantiomeric dibromides which is optically active C) a mixture of enantiomeric dibromides which is optically inactive D) (Z)-3,4-dibromo-3-hexene E) (E)-3,4-dibromo-3-hexene Answer: A Diff: 2 Section: 8.8
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57) Which of the following alkenes will yield a meso dihalide when reacted with Br2/CCl4 at room temperature? A)
B)
C)
D)
E) both Band D Answer: B Diff: 2 Section: 8.8 58) Provide the major organic product of the reaction below.
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Diff: 2 Section: 8.8
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59) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 1 Section: 8.8 60) Complete the following reaction and provide a detailed, step-by-step mechanism for the process.
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Diff: 1 Section: 8.8 61) Provide a detailed, step-by-step mechanism for the reaction shown below.
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Diff: 2 Section: 8.8
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62) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.8 63) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.8 64) Consider how the ICl bond is polarized and predict the product which results when this mixed halogen adds to 1-methylcyclohexene. Answer:
Diff: 3 Section: 8.8
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65) Provide the structure of the major organic product of the reaction below.
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Diff: 2 Section: 8.9 66) Predict the product of the following reaction. Include any relevant stereochemistry.
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Diff: 3 Section: 8.9 67) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.9
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68) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.9 69) Both (E)- and (Z)-hex-3-ene can be treated with D2 in the presence of a platinum catalyst. How are the products from these two reactions related to each other? A) The (E)- and (Z)-isomers generate the same products but in differing amounts. B) The (E)- and (Z)-isomers generate the same products in exactly the same amounts. C) The products of the two isomers are related as constitutional isomers. D) The products of the two isomers are related as diastereomers. E) The products of the two isomers are related as enantiomers. Answer: D Diff: 2 Section: 8.10 70) __________ is the use of an optically active reagent or catalyst to convert an optically inactive starting material into an optically active product. A) Asymmetric induction B) Racemization C) Optical reduction D) Meso effection E) Chiralization Answer: A Diff: 2 Section: 8.10 71) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
Answer: Diff: 1 Section: 8.10
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72) Humulene is a monocyclic terpene constituent of carnations. When 0.25 mol of humulene is hydrogenated in the presence of platinum catalyst, 0.75 mol of H2 reacts with the humulene to produce a monocyclic hydrocarbon of formula C15H30. What is the molecular formula of humulene? Answer: C15H24 Diff: 2 Section: 8.10 73) Complete the following reaction by filling in the necessary reagents.
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Diff: 3 Section: 8.11 74) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.11 75) Provide the reagents necessary to complete the following transformation.
Answer: 1. Br2, hν 2. NaOCH3, CH3OH 3. CH2I2, Zn(Cu) Diff: 3 Section: 8.11 24
76) Draw the Lewis structure of dibromocarbene. Answer: Diff: 3 Section: 8.11 77) Which of the following steps would successfully complete the following reaction?
A) I only B) II & III C) I & IV D) I, II, & IV Answer: A Diff: 3 Section: 8.12 78) Treatment of cyclopentene with peroxybenzoic acid __________. A) results in oxidative cleavage of the ring to produce an acyclic compound B) yields a meso epoxide C) yields an equimolar mixture of enantiomeric epoxides D) gives the same product as treatment of cyclopentene with OsO4 E) none of the above Answer: B Diff: 3 Section: 8.12
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79) Provide the major organic product of the reaction below.
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Diff: 2 Section: 8.12 80) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.12 81) Name the compound PhCO3H and give its most common use as a reagent. Answer: peroxybenzoic acid; an oxidizing agent which converts alkenes to epoxides Diff: 1 Section: 8.12 82) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.12
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83) A reaction of an unknown alkene with MCPBA in dichloromethane followed by work-up with H2O/H+ yielded, as the major product, a racemic mixture of (2S, 3S) and (2R, 3R)-3methylpentan-2,3-diol. What is the specific structure of the alkene used in the reaction? A) (Z)-3-methylpent-2-ene B) (E)-3-methylpent- 2-ene C) 2-methylpent-2-ene D) 2,3-dimethylbut-2-ene E) none of the above Answer: A Diff: 3 Section: 8.13 84) Provide the major organic product of the reaction below.
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Diff: 2 Section: 8.13 85) Provide the structure of the major organic product of the reaction below.
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Diff: 3 Section: 8.13
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86) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.13 87) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.13 88) Provide a detailed, step-by-step mechanism for the reaction shown below.
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Diff: 3 Section: 8.13
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89) Provide the reagents necessary to complete the following transformation.
Answer: 1. NaOCH3, CH3OH 2. MCPBA or CH3CO3H 3. H3O+ or -OH Diff: 3 Section: 8.13 90) Which of the following additions to alkenes occur(s) specifically in an syn fashion? A) dihydroxylation using OsO4, H2O2 B) addition of H2 C) hydroboration D) addition of HCl E) A, B, and C Answer: E Diff: 1 Section: 8.14 91) Provide the major organic product of the reaction below.
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Diff: 2 Section: 8.14
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92) Provide the major organic product of the following reaction.
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Diff: 2 Section: 8.14 93) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.14 94) Provide the reagents necessary to complete the following transformation.
Answer: 1. NaOCH3, CH3OH 2. OsO4, H2O2 or cold, dilute KMnO4, -OH Diff: 2 Section: 8.14
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95) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.14 96) An unknown compound with empirical formula C3H5 was treated with Br2/CCl4. The bromine solution went from orangish/red to clear immediately at room temperature. Upon treatment with O3 followed by work-up with dimethylsulfide the following products were identified. From the information provided what is/are the most likely structure(s) for this unknown compound.
A)
B)
C)
D)
E) both A and D Answer: A Diff: 2 Section: 8.15 31
97) How many moles of carbon dioxide are generated when one mole of the compound ahown is treated with warm, concentrated KMnO4?
A) 1 B) 2 C) 3 D) 4 E) 8 Answer: C Diff: 2 Section: 8.15 98) Give the structure of the alkene which would yield the following products upon ozonolysisreduction. CH3CH2CH2CH2CHO + CH2O Answer: CH3CH2CH2CH2CH=CH2 Diff: 1 Section: 8.15 99) Give the structure of the alkene which would yield the following products upon ozonolysisreduction. CH3COCH3 + CH3CH2CHO Answer: (CH3)2C=CHCH2CH3 Diff: 1 Section: 8.15 100) Provide the major organic product of the reaction below.
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Diff: 2 Section: 8.15
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101) Ozonolysis-reduction of an unknown alkene gives equal amounts of CH3CH2CHO and CH3CH2CH2CHO. Name the unknown alkene. Answer: Either (E)- or (Z)-3-heptene Diff: 2 Section: 8.15 102) Provide the major organic product of the following reaction.
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Diff: 2 Section: 8.15 103) Predict the structure of the products resulting from the reaction between limonene, a natural terpene found in citrus fruit, and ozone, followed by work up with dimethyl sulfide.
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Diff: 3 Section: 8.15
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104) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.15 105) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.15 106) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.15
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107) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 2 Section: 8.15 108) β-Ocimene is a natural product with a pleasant odor. Based on the information below, deduce the structure of β-ocimene.
Answer: Diff: 2 Section: 8.15 109) What alkene, which contains no oxygen atoms and a single C=C, will give CH3CO(CH2)4CHO upon treatment with OsO4 followed by cleavage with periodic acid? Answer: 1-methylcyclohexene Diff: 2 Section: 8.15 110) Draw the major organic product generated in the reaction below. Pay particular attention to regio- and stereochemical detail.
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Diff: 3 Section: 8.15
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111) Provide the structure of the product which results when the alkene below is treated with O3 followed by (CH3)2S.
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Diff: 3 Section: 8.15 112) Which of the following compounds is (are) appropriate to promote the cationic polymerization of isobutylene? A) H2SO4 B) BF3 C) ROOR D) NaOH E) both H2SO4 and BF3 Answer: E Diff: 2 Section: 8.16 113) When isobutylene [CH2=C(CH3)2] is treated with BF3, polyisobutylene is formed. Provide a step-by-step mechanism for this polymerization reaction. Answer:
Diff: 2 Section: 8.16
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114) Why can methyl acrylate (H2C=CHCO2CH3) be polymerized through anionic polymerization? Answer: The intermediate carbanion and the transition state leading to it are stabilized by the electron-withdrawing capacity of the carbonyl group. Diff: 2 Section: 8.16 115) What cyclic products results when 1,8-nonadiene is treated with Grubbs catalyst? Answer: cycloheptene Diff: 2 Section: 8.17 116) What olefin metathesis products result when 1-hexene is treated with Grubbs catalyst? What provides the thermodynamic driving force for this reaction? Answer: A mixture of (E)- and (Z)-5-decene products results. The thermodynamic driving force is the removal of the volatile ethylene by-product. Diff: 2 Section: 8.17
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