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Concept explainers
(a)
Interpretation:
An
Concept introduction:
E2 stands for bimolecular elimination. This reaction is a one-step concerted mechanism. In this step, the C-X and C-H bond breaks to form a double bond. The leaving group and the adjacent hydrogen atom must be anticoplanar in the precursor for the E2 step to be favored. To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion.
Since the alkyl halide and base influence the
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Answer to Problem 13.35P
An alkyl halide that could have been used to synthesize the known alkene exclusively via an E2 reaction paying attention to stereochemistry is:
Explanation of Solution
The structure of the desired alkene is:
The given alkene has both the higher priority groups attached on the opposite side of the double bond. Hence, the stereochemistry is E. Alkenes can be prepared from corresponding alkyl halides via E2 reactions. This reaction is a one-step concerted mechanism. In this step, the C-X and C-H bond breaks to form a double bond. The leaving group and the adjacent hydrogen atom must be anticoplanar in the precursor for the E2 step to be favored. To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion. Thus, the original alkyl halide that could have been used to prepare the given alkene must be:
To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion.
(b)
Interpretation:
An alkyl halide, that can be used to synthesize the given alkene exclusively via an E2 reaction paying attention to stereochemistry, is to be provided.
Concept introduction:
The name E2 represents bimolecular elimination. This reaction is a one-step concerted mechanism. In this step, the C-X and C-H bond breaks to form a double bond. The leaving group and the adjacent hydrogen atom must be anticoplanar in the precursor for the E2 step to be favored. To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion.
Since the alkyl halide and base influence the rate of reaction, this is a bimolecular reaction. A strong base is used to form the most substituted alkene as the major product.
![Check Mark](/static/check-mark.png)
Answer to Problem 13.35P
An alkyl halide that could have been used to prepare the given alkene exclusively via an E2 reaction paying attention to stereochemistry is:
Explanation of Solution
The structure of the required alkene is:
The given alkene has both the most priority groups attached on the same side of the double bond. Therefore, the stereochemistry about the double bond is Z. Alkenes can be prepared from corresponding alkyl halides via E2 reactions. This reaction is a one-step concerted mechanism. In this step, the C-X and C-H bond breaks to form a double bond. The leaving group and the adjacent hydrogen atom must be anticoplanar in the precursor for the E2 step to be favored. To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion. Thus, the original alkyl halide that could have been used to prepare the given alkene must be:
To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion.
(c)
Interpretation:
An alkyl halide, that can be used to synthesize the given alkene exclusively via an E2 reaction paying attention to stereochemistry, is to be provided.
Concept introduction:
The name E2 represents bimolecular elimination. This reaction is a one-step concerted mechanism. In this step, the C-X and C-H bond breaks to form a double bond. The leaving group and the adjacent hydrogen atom must be anticoplanar in the precursor for the E2 step to be favored. To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion.
Since the alkyl halide and base influence the rate of reaction, this is a bimolecular reaction. A strong base is used to form the most substituted alkene as the major product.
![Check Mark](/static/check-mark.png)
Answer to Problem 13.35P
An alkyl halide that could have been used to prepare the given alkene exclusively via an E2 reaction paying attention to stereochemistry is:
Explanation of Solution
The structure of the desired alkene is:
The alkene is a cycloalkene having two methyl groups attached to the double-bonded carbon atoms. As the carbon atoms in alkenes are
To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion.
(d)
Interpretation:
An alkyl halide, that can be used to synthesize the given alkene exclusively via an E2 reaction paying attention to stereochemistry, is to be provided.
Concept introduction:
The name E2 represents bimolecular elimination. This reaction is a one-step concerted mechanism. In this step, the C-X and C-H bond breaks to form a double bond. The leaving group and the adjacent hydrogen atom must be anticoplanar in the precursor for the E2 step to be favored. To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion.
Since the alkyl halide and base influence the rate of reaction, this is a bimolecular reaction. A strong base is used to form the most substituted alkene as the major product.
![Check Mark](/static/check-mark.png)
Answer to Problem 13.35P
An alkyl halide that could have been used to prepare the given alkene exclusively via an E2 reaction paying attention to stereochemistry is:
Explanation of Solution
The structure of the desired alkene is:
The alkene is cyclohexene having three methyl groups as substituents.
As the carbon atoms in alkenes are sp2 hybridized, all the atoms that are directly attached to the double-bonded carbon atoms must be in the plane. There are two chiral centers in the molecule at C3 and C6 carbon atoms. The stereochemistry for those two chiral centers will not change and will be retained as the reaction does not occur at those two chiral centers. Alkenes can be prepared from corresponding alkyl halides via E2 reactions.
This reaction is a one-step concerted mechanism. In this step, the C-X and C-H bond breaks to form a double bond. The leaving group and the adjacent hydrogen atom must be anticoplanar in the precursor for the E2 step to be favored. To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion. Thus, the original alkyl halide that could have been used to prepare the given alkene must be:
To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion.
(e)
Interpretation:
An alkyl halide, that can be used to synthesize the given alkene exclusively via an E2 reaction paying attention to stereochemistry, is to be provided.
Concept introduction:
The name E2 represents bimolecular elimination. This reaction is a one-step concerted mechanism. In this step, the C-X and C-H bond breaks to form a double bond. The leaving group and the adjacent hydrogen atom must be anticoplanar in the precursor for the E2 step to be favored. To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion.
Since the alkyl halide and base influence the rate of reaction, this is a bimolecular reaction. A strong base is used to form the most substituted alkene as the major product.
![Check Mark](/static/check-mark.png)
Answer to Problem 13.35P
An alkyl halide that could have been used to prepare the given alkene exclusively via an E2 reaction paying attention to stereochemistry is:
Explanation of Solution
The structure of the desired alkene is:
The alkene is cyclohexene having three methyl groups as substituents.
As the carbon atoms in alkenes are sp2 hybridized, all the atoms that are directly attached to the double-bonded carbon atoms must be in the plane. There are two chiral centers in the molecule at C3 and C6 carbon atoms. The stereochemistry for those two chiral centers will not change and will be retained as the reaction does not occur at those two chiral centers. Alkenes can be prepared from corresponding alkyl halides via E2 reactions.
This reaction involves a one-step mechanism (concerted) in which carbon-halogen bond and carbon-hydrogen bond breaks to form a double bond. The leaving group and the adjacent hydrogen atom must be anticoplanar in the precursor for the E2 step to be favored. To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion. Thus, the original alkyl halide that could have been used to synthesize the given alkene must be:
To arrive back at the alkyl halide, one must add hydrogen and a halogen on the alkene carbons in an anti-fashion.
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Chapter 13 Solutions
Organic Chemistry: Principles and Mechanisms (Second Edition)
- A student found that heating any one of the isomers shown here resulted in scrambling of the deuterium to all three positions on the five-membered ring. Propose a mechanism to account for this observation.arrow_forwardprovide the major product(s) and full mechanism for the following reactionsarrow_forwardDraw a mechanism to account for the formation of the NaOH product in the reaction shown here. Hint: Under these A conditions, deprotonation of a propargylic (C=C-CH) carbon is reversible.arrow_forward
- For each of the following reactions draw the structure of the major organic product in the box provided.Each numbered set of reagents above or below the arrow represents a complete separate reaction.For multi-step reactions give only the structure of the final product.arrow_forwardPredict the major reaction product for each of the following reactions. Pay attention to stereochemistry where appropriates.arrow_forwardCan someone explain to me the mechanism for the reaction? I don't know what type of reaction this is and how they add together to create the product. I do understand the actual product is correct because having all substituents equitorial is favorable.arrow_forward
- Predict the major products of each of the following reactions. Draw the complete detailed mechanism that leads to the formation of these products. Letters D and Earrow_forwardIn the given condensed formula, I understand that there will be a carbocation rearrangement due to excess hydrogen and an E1 mechanism, however, I have trouble in understanding where this bond between the nucleophile and electrophile is formed.arrow_forwardFor each of the following reactions, provide the structure of the major product and circle the predominant mechanism. Indicate the stereochemistry where necessary.arrow_forward
- Which reaction in each of the following pairs would you expect to be faster? (i) Write both reactions using bond-line presentation and, using arrows providing a mechanistic explanation of the course of the reaction, draw either a transition state or an intermediate product of the reaction; (ii) Shortly (one sentence) explain your reasoning why one of the two reactions will be faster.arrow_forward(SYN) 1,4-Cyclohexanedione monoethylene acetal is commercially available. (a) Show how you would use it to synthesize 4-ethylidenecyclohexanone. (b) What problems would arise if you tried to synthesize the same target from 1,4-cyclohexanedione? ? 1,4-Cyclohexanedione monoethylene acetal 4-Ethylidenecyclohexanonearrow_forwardProvide a complete, detailed mechanism for the reaction shown below. Use arrows to indicate the flow of electrons and draw the structure of all intermediates. Draw the structures of two other alkenes that could have produced the product shown above.arrow_forward
- Organic Chemistry: A Guided InquiryChemistryISBN:9780618974122Author:Andrei StraumanisPublisher:Cengage Learning
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