(a) Mechanism (circle one): SN2 or SN1 CH3 (b) Mechanism (circle one): SN2 or SN1 CH3 CH3 (c) Mechanism (circle one): E2 or E1 CH3 NaOH CH3 H₂O CH3 (d) Mechanism (circle one): E2 or E1 NaOH H₂O
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.
For each section, circle the mechanism from the two options given and draw the main organic product resulting from that mechanism. Indicate the stereochemistry and if two configurational isomers form, draw both.
![### Reaction Mechanisms with Substitution and Elimination
**(a) Mechanism (circle one): SN2 or SN1**
- **Reaction:** The substrate is a benzyl iodide derivative with a methyl group attached to the benzene ring. It reacts with NaOH.
- **Process:** Determine if the reaction proceeds via an SN2 (bimolecular nucleophilic substitution) or SN1 (unimolecular nucleophilic substitution) mechanism.
**(b) Mechanism (circle one): SN2 or SN1**
- **Reaction:** The same benzyl iodide substrate with a methyl group undergoes reaction with water (H₂O).
- **Process:** Decide if this reaction follows an SN2 or SN1 pathway.
**(c) Mechanism (circle one): E2 or E1**
- **Reaction:** The substrate is a secondary alkyl iodide with an additional methyl group next to the iodine. It reacts with NaOH.
- **Process:** Determine if the reaction occurs via an E2 (bimolecular elimination) or E1 (unimolecular elimination) mechanism.
**(d) Mechanism (circle one): E2 or E1**
- **Reaction:** The same secondary alkyl iodide with an additional methyl group reacts with water (H₂O).
- **Process:** Identify if the elimination follows an E2 or E1 mechanism.
### Explanation:
- **SN2:** Typically involves a one-step mechanism with the nucleophile attacking from the opposite side, leading to inversion of configuration.
- **SN1:** Involves a two-step mechanism starting with the formation of a carbocation, followed by nucleophilic attack.
- **E2:** A bimolecular reaction where a base removes a proton, leading to the formation of a double bond in one concerted step.
- **E1:** A two-step mechanism where the leaving group departs first to form a carbocation, followed by deprotonation leading to the formation of a double bond.
Understanding these mechanisms aids in predicting the products and conditions favorable for each pathway.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Ff26a788a-d14e-42e7-a1ad-e7a1405ef83f%2Ffb58bd4f-ab92-45a8-9978-d45cc1957601%2F33vj7op_processed.png&w=3840&q=75)
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