3. The following reaction is discussed in a later chapter of the textbook. It consists of four mechanistic steps. For each step (A-D), a. Draw in all implied lone pairs. b. Draw the appropriate curved arrows to show the bonds formation and bond breaking that occur. A B C D HH HH ΘΗ H ΘῊ HH + CH3 нон -CH3 H - t. ΘΗ + CH3 + H = CH3 O H HH = H-O-H HH H CH3 HH + CH3 CH3 O-H CH3 HOH
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.
![**Mechanistic Steps in a Reaction**
**Introduction:**
The following reaction is discussed in a later chapter of the textbook. It consists of four mechanistic steps (A–D). For each step, students need to:
a. Draw in all implied lone pairs.
b. Draw the appropriate curved arrows to show the bonds formation and bond breaking that occur.
**Step A:**
- **Reactants:** A compound with a benzene ring and an attached carbonyl group is reacting with methanol (CH₃OH) and a proton (H⁺).
- **Product:** Formation of an intermediate with a positive charge on the oxygen of the carbonyl group, and a separate methanol molecule with a positive charge on the oxygen.
**Step B:**
- The intermediate with the positively charged oxygen loses an alcohol group (in the form of water), leaving behind a structure with a positive charge on the carbon atom next to the benzene ring.
**Step C:**
- **Reactants:** A different structure with a benzene ring, a carbonyl group, and a protonated oxygen is reacting with methanol.
- **Product:** Formation of an intermediate with the original structure, but with an additional methyl group (CH₃) attached to the oxygen from methanol, leaving a positive charge on the oxygen.
**Step D:**
- The structure with the newly attached methyl group loses a proton, resulting in the final product with the oxygen no longer carrying a positive charge. Methanol, with a positive charge on the oxygen, is formed as a byproduct.
**Notes on Curved Arrows and Lone Pairs:**
- In each mechanistic step, appropriate curved arrows should be drawn to indicate the movement of electrons during bond formation and bond breaking.
- Lone pairs should be added to the structures where necessary to indicate potential sites of nucleophilic attack or charge stabilization.
This sequence illustrates a typical reaction mechanism involving proton transfers, formation of intermediates, and rearrangements leading to the final product.](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F49f9d394-65f9-403f-909c-32dbefeb4065%2Fcc5a4152-3ce3-4624-b4ac-92a584d05470%2Fma60ic9_processed.jpeg&w=3840&q=75)
![](/static/compass_v2/shared-icons/check-mark.png)
In the given reaction mechanism showing curved arrows from nucleophile electrophile.
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