(a)
To determine: The mechanism of the given reaction that accounts for racemisation with excess inversion.
Interpretation: The mechanism of the given reaction that accounts for racemisation with excess inversion is to be stated.
Concept introduction: The reaction between
(b)
To determine: The mechanism of the given reaction that accounts for complete retention of configuration.
Interpretation: The mechanism of the given reaction that accounts for complete retention of configuration is to be stated.
Concept introduction: The reaction between
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Organic Chemistry (9th Edition)
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- The reaction of butan-2-ol with concentrated aqueous HBr goes with partial racemization, giving more inversion thanretention of configuration. Propose a mechanism that accounts for racemization with excess inversion.(b) Under the same conditions, an optically active sample of trans-2-bromocyclopentanol reacts with concentrated aqueous HBr to give an optically inactive product, (racemic) trans-1,2-dibromocyclopentane. Proposea mechanism to show how this reaction goes with apparently complete retention of configuration, yet withracemization. (Hint: Draw out the mechanism of the reaction of cyclopentene with Br2 in water to give thestarting material, trans-2- bromocyclopentanol. Consider how parts of this mechanism might be involved in thereaction with HBr.)arrow_forward1) a. Propose a mechanism to account for the following reaction: 1-methylcyclohex-2-enol reacts with HI to give 3-iodo-3-methylcyclohex-1-ene and 3-iodo-1-methylcyclohex-1-ene. b. When 1-(1-methylethyl)cyclohexene (1-isopropylcyclohexene) is treated with a solution of HBr in Et₂0 2-bromo-2-cyclohexylpropane is the resulting product. Write the reaction and propose a mechanism using curved arrows to indicate the electron flow in each step c. Draw a mechanism that accounts for the following transformation. HO. LOCH3 com OCH3 CF3CO₂Harrow_forward1) a. Propose a mechanism to account for the following reaction: 1-methylcyclohex-2-enol reacts with HI to give 3-iodo-3-methylcyclohex-1-ene and 3-iodo-1-methylcyclohex-1-ene. b. When 1-(1-methylethyl)cyclohexene (1-isopropylcyclohexene) is treated with a solution of HBr in Et₂O 2-bromo-2-cyclohexylpropane is the resulting product. Write the reaction and propose a mechanism using curved arrows to indicate the electron flow in each step. c. Draw a mechanism that accounts for the following transformation. НО. LOCH3 OCH 3 CF3CO₂Harrow_forward
- Elimination of HBr from 2-bromobutane affords a mixture of 1-butene and 2-butene. With sodium ethoxide as base, 2-butene constitutes 81% of the alkene products, but with potassium tert-butoxide, 2-butene constitutes only 67% of the alkene products. Offer an explanation for this difference.arrow_forwardai. Reaction of the same 1-butene with cold KMnO4/ -OH gives compound ‘C’. Identify compound C. ii. Reaction of 1- butene with Hot KMnO4/-OH gives compound ‘D’ followed by acidification of the mixture to give compound ‘E’. Identify compounds D and E. iii. When 1- butene is treated with HBr in the presence of a peroxide, give the name and structure of the product formed. b. Dehydrohalogenation of alkylhalides always gives more than one product. Using 3, methyl 2-butyl chloride, explain this observation.arrow_forward8. Suggest a detailed step-by-step reaction mechanism for the reactions shown in a-b (use arrows to show electron flow). CH3 H3C CH3 (a) HO. ОН H,SO4 CH3 CH3 CH3OH CH3 (b) CH-I + HI OCH3arrow_forward
- Treatment of cis-4-bromocyclohexanol with HO– affords compound A and cyclohex-3-en-1-ol. Treatment of trans-4- bromocyclohexanol under the same conditions forms compound B and cyclohex-3-en-1-ol. A and B contain different functional groups and are not isomers of each other. Propose structures for A and B and offer an explanation for their formation.arrow_forward7. For each pair of compounds, say which compound is the best SN2 substrate.(a) 2-methyl-1-iodopropane or tert-butyl iodide(b) cyclohexyl bromide or 1-bromo-1-methylcyclohexane(c) 2-bromobutane or isopropyl bromide(d) 1-chloro-2,2-dimethylbutane or 2-chlorobutane(e) 1-iodobutane or 2-iodopropanearrow_forward3. For each of the reactions below, redraw the alkyl halide with the correct stereochemistry as indicated and provide mechanisms with explanations to account for the products observed. OCH, a. CH,OH R-enantiomer Racemic mixture b. NaCN H3C-Ç-CH2CH3 H3C-C-CH2CH3 Acetone CN Br R-enantiomer S-enantiomcr HIC HICarrow_forward
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