(a)
Interpretation:
The given reaction has to be identified as electro cyclic reaction, a cycloaddition reaction or a sigma tropic reaction.
Concept introduction:
Pericyclic reactions are “ any concerted reaction in which bonds are formed or broken in a cyclic transition state”. There is a single transition state from start to finish, in contrast to a stepwise reaction.
There are mainly three types of pericyclic reactions,
- 1) Electrocyclic reactions
- 2) Cycloaddition reactions
- 3) Sigmatropic reactions
In an electrocyclic reaction “one new sigma- bond is formed or broken.”
In a cycloaddition reaction “ two new sigma-bonds are formed or broken”
In a sigmatropic rearrangement reaction “ one new sigma-bond is formed as another breaks.”
(b)
Interpretation: The given reaction has to be identified as electro cyclic reaction, a cycloaddition reaction or a sigma tropic reaction.
Concept introduction:
Pericyclic reactions are “ any concerted reaction in which bonds are formed or broken in a cyclic transition state”. There is a single transition state from start to finish, in contrast to a stepwise reaction.
There are mainly three types of pericyclic reactions,
- 1) Electrocyclic reactions
- 2) Cycloaddition reactions
- 3) Sigmatropic reactions
In an electrocyclic reaction “one new sigma- bond is formed or broken.”
In a cycloaddition reaction “ two new sigma-bonds are formed or broken”
In a sigmatropic rearrangement reaction “ one new sigma-bond is formed as another breaks.”
(c)
Interpretation: The given reaction has to be identified as electro cyclic reaction, a cycloaddition reaction or a sigma tropic reaction.
Concept introduction:
Pericyclic reactions are “ any concerted reaction in which bonds are formed or broken in a cyclic transition state”. There is a single transition state from start to finish, in contrast to a stepwise reaction.
There are mainly three types of pericyclic reactions,
- 1) Electrocyclic reactions
- 2) Cycloaddition reactions
- 3) Sigmatropic reactions
In an electrocyclic reaction “one new sigma- bond is formed or broken.”
In a cycloaddition reaction “ two new sigma-bonds are formed or broken”
In a sigmatropic rearrangement reaction “ one new sigma-bond is formed as another breaks.”
(d)
Interpretation: The given reaction has to be identified as electro cyclic reaction, a cycloaddition reaction or a sigma tropic reaction.
Concept introduction:
Pericyclic reactions are “ any concerted reaction in which bonds are formed or broken in a cyclic transition state”. There is a single transition state from start to finish, in contrast to a stepwise reaction.
There are mainly three types of pericyclic reactions,
- 1) Electrocyclic reactions
- 2) Cycloaddition reactions
- 3) Sigmatropic reactions
In an electrocyclic reaction “one new sigma- bond is formed or broken.”
In a cycloaddition reaction “ two new sigma-bonds are formed or broken”
In a sigmatropic rearrangement reaction “ one new sigma-bond is formed as another breaks.”
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CHEM 262 ORG CHEM EBOOK DIGITAL DELIVERY
- Classify each reaction as an electrocyclic reaction, a cycloaddition, or a sigmatropic rearrangement. Label the σ bonds that are broken or formed in each reactionarrow_forwardWhich of the following statements is FALSE about pericyclic reactions? * Pericyclic reactions occur in a single step. The transition state of pericyclic reactions is cyclic. The outcome of pericyclic reactions vary depending on the identity of the solvent used. O There are no intermediates in a pericyclic reaction.arrow_forwardClassify each pericyclic reaction as an electrocyclic reaction, cycloaddition, or sigmatropic rearrangement. Indicate whether the stereochemistry is conrotatory, disrotatory, suprafacial, or antarafacial.arrow_forward
- Classify each pericyclic reaction as an electrocyclic reaction,cycloaddition, or sigmatropic rearrangement. Indicate whether thestereochemistry is conrotatory, disrotatory, suprafacial, or antarafacial.arrow_forwardWhich of the following statements about cycloaddition reactions is not true? Cycloaddition reactions form a cyclic product with two new bonds. The course of the reaction is determined by the symmetry of the molecular orbitals of the products. Cycloaddition reactions are concerted. Cycloaddition reactions are stereospecific.arrow_forwardAddition of HCl to alkene X forms two alkyl halides Y and Z. Explain why addition of HCl occurs at the indicated C=C (called anexocyclic double bond), rather than the other C=C (called anendocyclic double bond).arrow_forward
- To make Halocyclopentane, what reagents and substartes are needed? Which one(below) is related with the Halocyclopentane? Esterification, Alcohol Halogenation ,Alkyl Halide Solvolysis, Alkene Hydration, Hydroboration, Alkene Bromination, Alkene Dihydroxylation, Epoxidation, Diels Alder, Aldol, Grignard Addition, Benzene Nitration, Friedel-Crafts, Carbonyl Reduction, Claisen Condensation, Alcohol Oxidationarrow_forwardAddition of HCl to alkene X forms two alkyl halides Y and Z. (A) Label Y and Z as a kinetic or thermodynamic product and explain why. (B) Explain why the addition of HCl occurs at the exocyclic C=C, rather than the other C=Carrow_forwardElectrophilic addition to an alkene proceeds via Markovnikov regiochemistry due to the formation of the more stable carbocation intermediate. In the case of conjugated dienes, that is dienes that are separated by one sigma bond, the carbocation that is formed is stabilized additionally by resonance. Addition of the nucleophile to the carbocation intermediate can therefore give two types of products: direct addition to the double bond, also called 1,2-addition, and conjugate addition to the resonance stabilized carbocation, also called 1,4-addition.Allylic carbocation stability is affected by both the nature of the carbocation (primary allylic, secondary allylic, or tertiary allylic) and by the degree of substitution of the double bond. The latter is typically the dominant effect and so a primary allylic carbocation with a trisubstituted double bond is more stable than a tertiary allylic carbocation with a monosubstituted double bond.Electrophilic addition to a conjugated diene is…arrow_forward
- The 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_forwardaddition of hbr to a double bond with an ether (-or) substituent occurs regiospecifically to give a product in which the Br OR are bonded to the same carbon. Draw the two possible carbocation intermediates in this electrophilic addition reaction,and explain using resonance why the observed product is formed.arrow_forwardZaitsev's Rule refers to: which alkene is favored in a product mixture O how resonance contributors stabilize cations/anions/radicals O the stereochemistry of reaction intermediates/transition states O the stability of carbocation intermediatesarrow_forward