Reactive Intermediates
In chemistry, reactive intermediates are termed as short-lived, highly reactive atoms with high energy. They rapidly transform into stable particles during a chemical reaction. In specific cases, by means of matrix isolation and at low-temperature reactive intermediates can be isolated.
Hydride Shift
A hydride shift is a rearrangement of a hydrogen atom in a carbocation that occurs to make the molecule more stable. In organic chemistry, rearrangement of the carbocation is very easily seen. This rearrangement can be because of the movement of a carbocation to attain stability in the compound. Such structural reorganization movement is called a shift within molecules. After the shifting of carbocation over the different carbon then they form structural isomers of the previous existing molecule.
Vinylic Carbocation
A carbocation where the positive charge is on the alkene carbon is known as the vinyl carbocation or vinyl cation. The empirical formula for vinyl cation is C2H3+. In the vinyl carbocation, the positive charge is on the carbon atom with the double bond therefore it is sp hybridized. It is known to be a part of various reactions, for example, electrophilic addition of alkynes and solvolysis as well. It plays the role of a reactive intermediate in these reactions.
Cycloheptatrienyl Cation
It is an aromatic carbocation having a general formula, [C7 H7]+. It is also known as the aromatic tropylium ion. Its name is derived from the molecule tropine, which is a seven membered carbon atom ring. Cycloheptatriene or tropylidene was first synthesized from tropine.
Stability of Vinyl Carbocation
Carbocations are positively charged carbon atoms. It is also known as a carbonium ion.
![### Designation of Absolute Configuration in a Chemical Reaction
**Problem 13:**
Designate the absolute configuration of the major product of this reaction:
**Reaction Details:**
- The starting material is represented with the chiral center having an (R) absolute configuration.
- The structure of the starting material includes a hydrogen (H) atom, a bromine (Br) atom, and an ethyl group, with the configuration around the chiral center depicted using wedge-and-dash bonds.
- The chemical reagent used in the reaction is sodium methoxide (CH₃ONa).
**Diagram Explanation:**
The starting material has a chiral center marked (R), with the following groups attached:
- Bromine (Br) on a wedge bond (indicating it is coming out of the plane towards the observer).
- Hydrogen (H) on a dash bond (indicating it is going behind the plane away from the observer).
- An ethyl group is also attached but not specifically depicted in terms of spatial orientation in the image.
The reaction arrow indicates that the compound is treated with sodium methoxide (CH₃ONa), a common nucleophile in organic chemistry.
**Task:**
Determine the absolute configuration of the major product after the reaction.
### Analysis and Solution:
When sodium methoxide reacts with the given compound, a nucleophilic substitution reaction occurs. Sodium methoxide will typically attack the carbon atom bonded to bromine, leading to the departure of the bromine atom and the formation of a new bond with the methoxide ion (CH₃O⁻).
**Steps to determine the configuration:**
1. Recognize the type of reaction (likely SN2) which involves inversion of configuration at the chiral center.
2. Apply the Cahn-Ingold-Prelog priority rules to assign the configuration of the product.
By recognizing that the configuration at the chiral center inverts during an SN2 reaction, the absolute configuration of the product will switch from (R) to (S).
### Conclusion:
The absolute configuration of the major product of the given reaction, where a chiral center with initial (R) configuration undergoes nucleophilic substitution with sodium methoxide, is (S).
These details and step-by-step analysis provide a clear understanding of how to designate the absolute configuration of the reaction's major product.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F1c9ec205-c724-4ca2-b5f2-e7d121be95e9%2Ffb782831-b47c-4408-8bb4-037eefff9489%2Fmjqnpb_processed.jpeg&w=3840&q=75)
![](/static/compass_v2/shared-icons/check-mark.png)
Trending now
This is a popular solution!
Step by step
Solved in 3 steps with 1 images
![Blurred answer](/static/compass_v2/solution-images/blurred-answer.jpg)
![Chemistry](https://www.bartleby.com/isbn_cover_images/9781305957404/9781305957404_smallCoverImage.gif)
![Chemistry](https://www.bartleby.com/isbn_cover_images/9781259911156/9781259911156_smallCoverImage.gif)
![Principles of Instrumental Analysis](https://www.bartleby.com/isbn_cover_images/9781305577213/9781305577213_smallCoverImage.gif)
![Chemistry](https://www.bartleby.com/isbn_cover_images/9781305957404/9781305957404_smallCoverImage.gif)
![Chemistry](https://www.bartleby.com/isbn_cover_images/9781259911156/9781259911156_smallCoverImage.gif)
![Principles of Instrumental Analysis](https://www.bartleby.com/isbn_cover_images/9781305577213/9781305577213_smallCoverImage.gif)
![Organic Chemistry](https://www.bartleby.com/isbn_cover_images/9780078021558/9780078021558_smallCoverImage.gif)
![Chemistry: Principles and Reactions](https://www.bartleby.com/isbn_cover_images/9781305079373/9781305079373_smallCoverImage.gif)
![Elementary Principles of Chemical Processes, Bind…](https://www.bartleby.com/isbn_cover_images/9781118431221/9781118431221_smallCoverImage.gif)