Consider the resonance scheme shown below. Select the correct answer from the list below. , an arrow incorrectly starts at the positive charge the charge on the carbons needs to be negative This mechanism is free of errors. the charge on the carbons is not positive
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.
#### Description of the Diagram:
The given diagram shows two resonance structures of an organic molecule. The first structure has a positive charge on a carbon atom with an arrow indicating the electron movement. The arrow starts from a lone pair on a nearby carbon atom and points towards an adjacent double bond, indicating the shift of electrons to form the second resonance structure.
#### Answer Options:
1. ○ an arrow incorrectly starts at the positive charge
2. ○ the charge on the carbons needs to be negative
3. ○ This mechanism is free of errors.
4. ○ the charge on the carbons is not positive
#### Explanation of the Diagram:
- The first resonance structure has a positive charge on a carbon atom.
- The arrow indicates electron movement but incorrectly starts at the positive charge; this should originate from a lone pair or a bond.
- The arrow movement suggests that electrons are moving, transforming the structure into another valid resonance form.
- The second resonance structure shows the electron movement resulting in a double-bonded structure with a positive charge on a different carbon atom.
#### Which option is correct?
The correct interpretation of the resonance structure mechanism can help identify the accurate option from the list.
The mechanism presented shows a common error where the arrow starts from a positive charge, which is incorrect. The arrow should start from the lone pair or bonded electrons and not from the positive charge. Therefore, the correct answer is:
- ○ an arrow incorrectly starts at the positive charge](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F3991c7bd-acfb-40ed-bb56-29190279c7cb%2Fba784bcb-dceb-4e66-ba44-56a2e620b353%2Fp84n0l0n_processed.jpeg&w=3840&q=75)
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