A chemist allows some pure (2S,3R)-3-bromo-2,3-diphenylpentane to react with a solution of sodium ethoxide(NaOCH2 CH3) in ethanol. The products are two alkenes: A (cis-trans mixture) and B, a single pure isomer. Under the same conditions, the reaction of (2S,3S)-3-bromo-2,3-diphenylpentane gives two alkenes, A (cis-trans mixture) and C. Upon catalytic hydrogenation, all three of these alkenes (A, B, and C) give 2,3-diphenylpentane. Determine the structures of A, B, and C; give equations for their formation; and explain the stereospecificity of these reactions.

A chemist allows some pure (2S,3R)-3-bromo-2,3-diphenylpentane to react with a solution of sodium ethoxide(NaOCH2 CH3) in ethanol. The products are two alkenes: A (cis-trans mixture) and B, a single pure isomer. Under the same conditions, the reaction of (2S,3S)-3-bromo-2,3-diphenylpentane gives two alkenes, A (cis-trans mixture) and C. Upon catalytic hydrogenation, all three of these alkenes (A, B, and C) give 2,3-diphenylpentane. Determine the structures of A, B, and C; give equations for their formation; and explain the stereospecificity of these reactions.

Organic Chemistry

8th Edition

ISBN:9781305580350

Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Publisher:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. Foote

Chapter9: Nucleophilic Substitution And Β-elimination

Section9.7: Experimental Evidence For E1 And E2 Mechanisms

Problem 9.7P

See similar textbooks

Similar questions

Following are diastereomers (A) and (B) of 3-bromo-3,4-dimethylhexane. On treatment with sodium ethoxide in ethanol, each gives 3,4-dimethyl-3-hexene as the major product. One diastereomer gives the E alkene, and the other gives the Z alkene. Which diastereomer gives which alkene? Account for the stereoselectivity of each -elimination.
OChem HELP... Draw the conformational structures (chair or boat conformations) for the MAJOR product formed when 1-tert-butylcyclohexene reacts with each of the following reagents. Also, indicate if the product obtained is racemic form. a) Br2, CCl4 b) Br2, H2O c) OsO4, then aqueous NaHSO3 d) ICl e) mCPBA, then H3O+, H20 f) O3, then Me2S (conformational structure not required) g) BH3:THF, then H2O2, HO- h) D2, Pt i) Hg(OAc)2 in THF-H2O, then NaBH4, HO- j) BD3 :THF, then CH3CO2T
Which stereoisomer of 3-hexene forms (3S,4S)-4-bromo-3-hexanol and (3R,4R)-4-bromo-3-hexanol when it reacts with Br2 and H2O?
Predict the major products of the following reactions. Include stereochemistry whereapplicable.(a) 1@methylcycloheptene + BH3 # THF, then H2O2, OH-(b) trans@4,4@dimethylpent@2@ene + BH3 # THF, then H2O2, OH
The compound 3,4-dimethyl-hexan-3-ol of 3R, 4S configuration is treated with a concentrated HBr solution at room temperature. A mixture of two stereoisomers is obtained.If the reaction mixture above is heated, the appearance of several other compounds is observed. 1) Draw the different compounds obtained using the wedge-flywheel representation. 2) What is the majority product? Explain 3) Propose a modification of the experimental conditions in order to obtain the exclusive formation of these compounds obtained after heating
Ozonolysis (O3 in CH2Cl2) of compound A under reducing conditions (Zn /acetic acid) gives formaldehyde, 2-butanone, and compound B. Catalytic hydrogenation (H2/Pd) of A gives 2,7-dimethylnonane. What is a possible structure for compound A? a. 2,7-Dimethyl-2,8-nonadieneb. 2,7-Dimethyl-1,8-nonadienec. 2,7-Dimethyl-1,6-nonadiened. 2,7-Dimethyl-1,7-nonadiene
Benzene is one of the compounds used as octane enhancers in unleaded gasoline. It is manufactured by thecatalytic conversion of acetylene to benzene: 3C2 H2(g) ⇌ C6 H6(g). Which value of Kc would make this reactionmost useful commercially? Kc ≈ 0.01, Kc ≈ 1, or Kc ≈ 10. Explain your answer
When buta-1,3-diene (CH2 = CH – CH = CH2) is treated with HBr, two constitutional isomers are formed, CH3CHBrCH = CH2 and BrCH2CH = CHCH3. Draw a stepwise mechanism that accounts for the formation of both products.
cis-1-Bromo-4-tert-butylcyclohexane and trans-1-bromo-4-tert-butylcyclohexane both react with sodium ethoxide in ethanol to form 4-tert-butylcyclohexene. Explain why the cis isomer reacts much more rapidly than the trans isomer.
Compounds A and B are isomers having molecular formula C5H12. Heating A with Cl2 gives a single product of monohalogenation, whereas heating B under the same conditions forms three constitutional isomers. What are thestructures of A and B?
(1) Predict the outcome of the addition of HBr to (a) trans-2-pentene, (b) 2-methyl-2-butene, and (c) 4-methylcyclohexene. How many isomers can be formed in each case? (2) Addition of HBr to 3,3-dimethyl-1-butene gives a mixture of two isomeric alkyl bromide products. Draw structures for the two products, and give a mechanistic explanation for their formation.
There are three constitutional isomers with the molecular formula C5H12. Chlorination of one of these isomers yields only one product. Identify the isomer: