(a)
Interpretation: The product formed from the
Concept introduction: Sigmatropic rearrangements are pericyclic reactions which involve the migration of sigma bonds. In these reactions, old sigma bonds are broken and new sigma bonds are formed.
Curved arrows aid in determining the movement and flow of electrons in the reaction. The electrons that take part in the
(b)
Interpretation: If the given reaction proceeds in a suprafacial or antarafacial manner under thermal conditions is to be predicted.
Concept introduction: Sigmatropic rearrangements are pericyclic reactions which involve the migration of sigma bonds. In these reactions, old sigma bonds are broken and new sigma bonds are formed.
Curved arrows aid in determining the movement and flow of electrons in the reaction. The electrons that take part in the chemical reactions are shown by the curved arrows.
(c)
Interpretation: If the given reaction proceeds in a suprafacial or antarafacial manner under photochemical conditions is to be predicted.
Concept introduction: Sigmatropic rearrangements are pericyclic reactions which involve the migration of sigma bonds. In these reactions, old sigma bonds are broken and new sigma bonds are formed.
Curved arrows aid in determining the movement and flow of electrons in the reaction. The electrons that take part in the chemical reactions are shown by the curved arrows.
Trending nowThis is a popular solution!
Chapter 27 Solutions
ORGANIC CHEMISTRY
- The bicyclic alkene P can be prepared by thermal electrocyclic ring closure from cyclodecadiene Q or by photochemical electrocyclic ring closure from cyclodecadiene R. Draw the structures of Q and R, and indicate the stereochemistry of the process by which each reaction occurs.arrow_forward(a) When cis-1-bromo-2-methylcyclohexane undergoes an E2 reaction, two products (cycloalkenes) are formed. What are these two cycloalkenes, and which would you expect to be the major product? Write conformational structures showing how each is formed. (b) When rans-1-bromo-2-methylcyclohexane reacts in an E2 reaction, only one cyclo- alkene is formed. What is this product? Write conformational structures showing why it is the only product.arrow_forwardGive the structure, exclusive of stereochemistry, of the principal organic product formed on reaction of 2,3-dimethyl-1,3-butadiene with each of the following:(a) 2 mol H2, platinum catalyst(b) 1 mol HCl (product of 1,2-addition)(c) 1 mol HCl (product of 1,4-addition)(d) 1 mol Br2 (product of 1,2-addition)(e) 1 mol Br2 (product of 1,4-addition)(f) 2 mol Br2arrow_forward
- Reaction of this bicycloalkene with bromine in carbon tetrachloride gives a trans dibro- mide. In both (a) and (b), the bromine atoms are trans to each other. However, only one of these products is formed. CH3 CH3 CH3 Br Br CH,Cl, + Br2 or Br Br (a) (b) Which trans dibromide is formed? How do you account for the fact that it is formed to the exclusion of the other trans dibromide?arrow_forward4.35 Formulate the reaction of cyclohexene with (i) Br2 and (ii) meta-chloro- peroxybenzoic acid followed by H30+. Show the reaction intermediates and the final products with correct cis or trans stereochemistry. 4.36 What products would you expect to obtain from reaction of cyclohexa- 1,3-diene with each of the following? (a) 1 mol Br2 in CH2C12 (c) 1 mol DCl (D = deuterium, ²H) (b) 1 mol HCl (d) 2 mol H2 over a Pd catalyst 4.37 Predict the products of the following reactions on hex-1-yne: (a) 1 equiv HBr ? (b) 1 equiv Cl2 ? (c) H2, Lindlar catalystarrow_forwardDraw the organic product obtained on treatment of each of the following two alkenes with bromine: (a) trans-2-pentene and (b) 1- methylcyclohexene. Having done this, draw the product of the reaction of these same alkenes with bromine in aqueous solution.arrow_forward
- 1.What is the product of the reaction between 1,3-dibutene and bromoethene? (A) No reaction occurs (B) 4-bromocyclohexene (C) 3-bromocyclohexene (D) 3-bromocyclopentene 2. Cyclohexene undergoes hydrobromination. Which of these is a possible product? (A) Bromocyclohexane (B) All of these (C) Trans 1,2-dibromocyclohexane (D) Cis 1,2-dibromocyclohexane 3. A hydrocarbon molecule is saturated if the molecule contains (A) Single covalent bonds, only (B) A double covalent bond, only (C) A triple covalent bond (D) Single and double covalent bondsarrow_forwardPara-substituted product was produced when phenol reacts with cyclohexanecarbonyl bromide in the presence of AIB13. -Br Cyclohexanecarbonyl bromide (i) Outline the mechanism for this reaction. (ii) Draw the alternative substituted product formed.arrow_forward(a) Explain how pyrrole is isoelectronic with the cyclopentadienyl anion.(b) Specifically, what is the difference between the cyclopentadienyl anion and pyrrole?(c) Draw resonance forms to show the charge distribution on the pyrrole structure.arrow_forward
- 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_forwardThe bicyclic alkene P can be prepared by thermal electrocyclic ringclosure from cyclodecadiene Q or by photochemical electrocyclic ringclosure from cyclodecadiene R. Draw the structures of Q and R, andindicate the stereochemistry of the process by which each reactionoccurs.arrow_forwardQ4 Which statement below about Snl reactions is incorrect? (A) SNl reactions are stepwise and have intermediates. (B) The slow step in a Snl reaction is formation of the carbocation intermediate. (C) SNl reactions have first order kinetics which means only the alkyl halide is involved in the rate limiting step. (D) The products of a Syl reaction will be a pair of enantiomers. (E) An aprotic solvent is best for Snl reactions as they tend to help stabilize carbocation intermediates.arrow_forward
- ChemistryChemistryISBN:9781305957404Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCostePublisher:Cengage LearningChemistryChemistryISBN:9781259911156Author:Raymond Chang Dr., Jason Overby ProfessorPublisher:McGraw-Hill EducationPrinciples of Instrumental AnalysisChemistryISBN:9781305577213Author:Douglas A. Skoog, F. James Holler, Stanley R. CrouchPublisher:Cengage Learning
- Organic ChemistryChemistryISBN:9780078021558Author:Janice Gorzynski Smith Dr.Publisher:McGraw-Hill EducationChemistry: Principles and ReactionsChemistryISBN:9781305079373Author:William L. Masterton, Cecile N. HurleyPublisher:Cengage LearningElementary Principles of Chemical Processes, Bind...ChemistryISBN:9781118431221Author:Richard M. Felder, Ronald W. Rousseau, Lisa G. BullardPublisher:WILEY