Guided course 06:01General features of acid-catalyzed dehydration.Johnny Betancourt2629views24rank6comments
Guided course 05:20Dehydration of 1° alcohols:The E2 MechanismJohnny Betancourt2230views21rank17comments
Guided course 05:21Dehydration of 2° and 3° alcohols:The E1 Mechanism.Johnny Betancourt2226views22rank11comments
Guided course 01:06An extra note of caution with 1° alcohols.Johnny Betancourt1570views15rank7comments
Textbook QuestionE1 eliminations of alkyl halides are rarely useful for synthetic purposes because they give mixtures of substitution and elimination products. Explain why the sulfuric acid-catalyzed dehydration of cyclohexanol gives a good yield of cyclohexene even though the reaction goes by an E1 mechanism. (Hint: What are the nucleophiles in the reaction mixture? What products are formed if these nucleophiles attack the carbocation? What further reactions can these substitution products undergo?)579views
Textbook QuestionPredict the products of the following reactions. When more than one product is expected, predict which will be the major product. (a) H2SO4, heat—> (b) . H3PO4, heat—> (c) H2SO4, heat—> 1215views
Textbook QuestionPredict the major products of acid-catalyzed dehydration of the following alcohols. (a) pentan-2-ol (b) 1-methylcylcopentanol 987views
Textbook QuestionPropose mechanisms for the following reactions. Additional products may be formed, but your mechanism only needs to explain the products shown. c. H2SO4, heat—> + 678views
Textbook QuestionShow the product(s) you expect from dehydration of the following alcohols when they are heated in sulfuric or phosphoric acid. In each case, use a mechanism to show how the products are formed. (a) 1078views
Textbook QuestionPropose mechanisms for the following reactions. (d) H2SO4/H2O, heat—> (an interesting minor product) 2012views
Textbook QuestionPropose mechanisms for the following reactions. (c) 2-methylclyclohexanol H2SO4, heat—> 1-methylcyclohexene + 3-methylcyclohexene + methylenecyclohexane 1319views
Textbook QuestionPropose mechanisms for the following reactions. (b) pentan-2-ol H2SO4, heat—> pent-1-ene + pent-2-ene (cis + trans) 1721views
Textbook QuestionPropose mechanisms for the following reactions. (a) cyclopentanol H2SO4, heat—> cyclopentene 2720views2rank
Textbook QuestionShow the product(s) you expect from dehydration of the following alcohols when they are heated in sulfuric or phosphoric acid. In each case, use a mechanism to show how the products are formed.(b) <IMAGE> 247views
Textbook Question(•••) THINKING AHEAD The acid-catalyzed hydration we learned here in Chapter 8 is reversible [we introduce this reaction in Chapter 13]: (a) Propose a mechanism for the formation of an alkene from an alcohol.445views
Textbook Question(•••) THINKING AHEAD The acid-catalyzed hydration we learned here in Chapter 8 is reversible [we introduce this reaction in Chapter 13]: (d) How might you shift the equilibrium to the right?445views
Textbook Question(•••) THINKING AHEAD The acid-catalyzed hydration we learned here in Chapter 8 is reversible [we introduce this reaction in Chapter 13]: (e) How might you shift the equilibrium to the left?382views
Textbook QuestionIf the compound shown in the margin is heated in the presence of H2SO4, a. what constitutional isomer would be formed in greatest yield? b. what stereoisomer would be formed in greater yield?526views
Textbook QuestionStarting from bromobenzene and any other reagents and solvents you need, show how you would synthesize the following compounds. Any of these products may be used as starting materials in subsequent parts of this problem. (c) 1-phenylpropan-2-ol828views
Textbook QuestionExplain why the acid-catalyzed dehydration of an alcohol is a reversible reaction, whereas the base-promoted dehydrohalogenation of an alkyl halide is an irreversible reaction.874views
Textbook QuestionWhat stereoisomers are formed in the following reactions? Which stereoisomer is the major product? a. the acid-catalyzed dehydration of 1-pentanol to 2-pentene613views
Textbook QuestionExplain why the following alcohols, when heated with acid, form the same alkene. 482views
Textbook QuestionWhen the following seven-membered ring alcohol is dehydrated, three alkenes are formed. Propose a mechanism for their formation. 611views
Textbook QuestionWhen heated with H2SO4, both 3,3-dimethyl-2-butanol and 2,3-dimethyl-2-butanol are dehydrated to form 2,3-dimethyl-2-butene. Which alcohol dehydrates more rapidly?1143views
Textbook QuestionWhat is the major product obtained when each of the following alcohols is heated in the presence of H2SO4? b. 429views
Textbook QuestionWhat is the major product obtained when each of the following alcohols is heated in the presence of H2SO4? a. 512views
Textbook QuestionPredict the major products of dehydration catalyzed by sulfuric acid. (a) hexan-1-ol (b) hexan-2-ol (c) pentan-3-ol1468views
Textbook QuestionIdentify the alcohol(s) that would produce the following alkenes under the given conditions. (a)636views
Textbook QuestionWhen HCl was used for the attempted dehydration reaction shown, a reaction occurred, but none of the desired product was formed. Suggest the identity of the actual product obtained.371views
Textbook QuestionIdentify two different alcohols that can be dehydrated (one with rearrangement) to form the alkene shown.506views
Textbook QuestionIdentify two different alcohols that can be dehydrated (one without rearrangement) to form the alkene shown.438views
Textbook QuestionIdentify the alcohol(s) that would produce the following alkenes under the given conditions.(b) <IMAGE>298views
Textbook QuestionIdentify the alcohol(s) that would produce the following alkenes under the given conditions.(c) <IMAGE>304views
Textbook Question(•••) When using sulfuric acid, but in the absence of other nucleophiles like water or bromide ion, less stable alkenes can be isomerized to their more stable isomer. Provide a mechanism for these acid-catalyzed isomerization reactions. [This is one illustration of the principle of microscopic reversibility.](a) <IMAGE>334views
Textbook Question(••••) Suggest a mechanism for the following reactions.(c) Elimination : <IMAGE> 327views
Textbook Question(•••) Suggest a mechanism for the following substitution reaction. [We studied a similar reaction of radicals in Assessment 11.53.]<IMAGE>297views
Textbook Question(••) Predict the product(s) that would result when molecules (a)–(p) are allowed to react under the following conditions: (vi) H₂SO₄. If no reaction occurs, write 'no reaction.' (a) <IMAGE>277views
Textbook Question(•••) THINKING AHEAD The acid-catalyzed hydration we learned here in Chapter 8 is reversible [we introduce this reaction in Chapter 13]:<IMAGE>(c) Which side of the reaction would be favored by running the reaction at high temperatures?340views
Textbook QuestionWhat product is obtained when the following vicinal diol is heated in an acidic solution?<IMAGE>285views
Textbook QuestionWhat stereoisomers are formed in the following reactions? Which stereoisomer is the major product?b. the acid-catalyzed dehydration of 3,4-dimethyl-3-hexanol to 3,4-dimethyl-3-hexene282views
Textbook QuestionIndicate which alcohol in each pair undergoes an elimination reaction more rapidly when heated with H2SO4.a. <IMAGE>b. <IMAGE>291views
Textbook QuestionExplain why (S)-2-butanol forms a racemic mixture when it is heated in sulfuric acid.291views
Textbook QuestionWhat alkenes would you expect to be obtained from the acid-catalyzed dehydration of 1-hexanol?280views
Textbook QuestionIndicate which alcohol in each pair undergoes an elimination reaction more rapidly when heated with H2SO4.e. <IMAGE>321views
Textbook QuestionIndicate which alcohol in each pair undergoes an elimination reaction more rapidly when heated with H2SO4.d. <IMAGE>223views
Textbook QuestionIndicate which alcohol in each pair undergoes an elimination reaction more rapidly when heated with H2SO4.c. <IMAGE>293views
Textbook QuestionPropose mechanisms for the following reactions.HINT: Alcohol dehydrations usually go through E1 elimination of the protonated alcohol, with a carbocation intermediate. Rearrangements are common.(b) <IMAGE> H2SO4, heat—> <IMAGE> + <IMAGE> + <IMAGE> 255views
Textbook QuestionPropose mechanisms for the following reactions.HINT: Alcohol dehydrations usually go through E1 elimination of the protonated alcohol, with a carbocation intermediate. Rearrangements are common.d. <IMAGE>. H2SO4, heat—> <IMAGE> + <IMAGE> + <IMAGE> 209views
Textbook QuestionUnder acid catalysis, tetrahydrofurfuryl alcohol reacts to givesurprisingly good yields of dihydropyran.Propose a mechanism to explain this useful synthesis.<IMAGE of reaction>3views
Textbook QuestionWhen the following substituted cycloheptanol undergoesdehydration, one of the minor products has undergonea ring contraction.Propose a mechanism to show how this ring contraction occurs.<IMAGE of a reaction>264views
Textbook QuestionPropose mechanisms for the following reactions. In most cases,more products are formed than are shown here. You onlyneed to explain the formation of the products shown, however.(b) <IMAGE of reaction>246views
Textbook QuestionWrite a balanced equation for each reaction, showing the major product you expect.(a) CH3-CH2-CH(CH3)OH H2SO4, heat—> 246views
Textbook QuestionWrite a balanced equation for each reaction, showing the major product you expect.(c) <IMAGE> H2SO4, heat—> 231views
Textbook QuestionShow the product(s) you expect from dehydration of the following alcohols when they are heated in sulfuric or phosphoric acid. In each case, use a mechanism to show how the products are formed.(c) <IMAGE> 244views
Textbook QuestionWrite a mechanism that explains the formation of the following product. In your mechanism, explain the cause of the rearrangement, and explain the failure to form the Zaitsev product.<IMAGE> H2SO4, heat—> <IMAGE> 214views
Textbook QuestionPredict the products of the sulfuric acid-catalyzed dehydration of the following alcohols. When more than one product is expected, label the major and minor products.(d)1-isopropylcyclohexanol(e) 2-methylcyclohexanol268views
Textbook QuestionPropose mechanisms for the following reactions. Additional products may be formed, but your mechanism only needs to explain the products shown.(b) <IMAGE> H2SO4, heat—> <IMAGE> + <IMAGE> + <IMAGE>173views
Textbook QuestionFour pairs of compounds are shown. In each pair, one ofthe compounds reacts more quickly, or with a more favorableequilibrium constant, than the less conjugated system.In each case, explain the enhanced reactivity.(c) <IMAGE>229views
Textbook QuestionPropose a mechanism for each reaction. (a) < of reaction> (b) < of reaction>489views
Textbook QuestionSuggest an alkene that, in two steps, could be converted into each of the following ketones. Each sequence should involve a pinacol rearrangement.(c) <IMAGE>188views
Textbook QuestionThe following reaction is called the pinacol rearrangement. The reaction begins with an acid-promoted ionization to give a carbocation. This carbocation undergoes a methyl shift to give a more stable, resonance-stabilized cation. Loss of a proton gives the observed product. Propose a mechanism for the pinacol rearrangement. (CH3)2C(OH)C(CH3)2OH pinacol H2SO4, heat—> pinacolone H3CC(=O)C(CH3)3 738views
Textbook QuestionTreatment of the following alcohol was expected to give alkene A. Instead, B was produced as the major product. Suggest a mechanism by which B formed.<IMAGE>425views
Textbook QuestionAlthough 2-methyl-1,2-propanediol is an unsymmetrical vicinal diol, only one product is obtained when it is dehydrated in an acidic solution. a. What is this product?515views
Textbook QuestionA student was studying terpene synthesis, and she wanted to make the compound shown here. First she converted 3-bromo-6-methylcyclohexene to alcohol A. She heated alcohol A with sulfuric acid and purified one of the components (compound B) from the resulting mixture. Compound B has the correct molecular formula for the desired product. (c) Propose a mechanism for the dehydration of alcohol A to compound B. 605views
Textbook QuestionWhich of the following alcohols dehydrates the fastest when heated with acid? 547views
Textbook QuestionPropose mechanisms for the following reactions. Additional products may be formed, but your mechanism only needs to explain the products shown.a. CH3-CH2-CH2-CH2-OHCH2=CH-CH2CH3 (Hint: Hydride shift)272views
Textbook QuestionPredict the major products of acid-catalyzed dehydration of the following alcohols.(c) 2-methylcyclohexanol(d) 2,2-dimethylpropan-1-ol287views
Textbook QuestionA vicinal diol has OH groups on adjacent carbons. The dehydration of a vicinal diol is accompanied by a rearrangement called the pinacol rearrangement. Propose a mechanism for this reaction.<IMAGE>475views
Textbook QuestionPropose mechanisms for the following reactions. In most cases,more products are formed than are shown here. You onlyneed to explain the formation of the products shown, however.(c) <IMAGE of reaction>188views