When 3-pentanone and ethanol are reacted in an acetal formation reaction in the presence of acid catalyst, the resulting FINAL acetal product has _____ bonded to the four different sides of the central carbon. [NOTE: The numbers in the responses should be subscripted.] [Exam question & (if applicable) response options © 2021 James Y. Chen. All rights reserved.] O -CH2CH3, -CH2CH3, -OCH2CH3, and -OCH2CH3 O -CH2CH3, -CH2CH3, -OCH2CH3, and -OH O -H, -CH2CH3, -OCH2CH3, and -OCH2CH3 O -(CH2)4CH3, -(CH2)4CH3, -OCH2CH3, and -OCH2CH3 O -CH2CH3, -CH2CH3, -OCH2CH2CH3, and -OCH2CH2CH3
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.
![### Chemical Reactions and Product Formation
**Question:**
When 3-pentanone and ethanol are reacted in an acetal formation reaction in the presence of an acid catalyst, the resulting FINAL acetal product has ______ bonded to the four different sides of the central carbon.
*[NOTE: The numbers in the responses should be subscripted.]*
**Options:**
- ○ –CH₂CH₃, –CH₂CH₃, -OCH₂CH₃, and -OCH₂CH₃
- ○ –CH₂CH₃, –CH₂CH₃, -OCH₂CH₃, and -OH
- ○ -H, –CH₂CH₃, -OCH₂CH₃, and -OCH₂CH₃
- ○ -(CH₂)₄CH₃, -(CH₂)₄CH₃, -OCH₂CH₃, and -OCH₂CH₃
- ○ –CH₂CH₃, –CH₂CH₃, -OCH₂CH₃, and -OCH₂CH₂CH₃
*[Exam question & (if applicable) response options © 2021 James Y. Chen. All rights reserved.]*
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In this question, we are examining the product of an acetal formation reaction involving 3-pentanone and ethanol under acidic conditions. Understanding acetal formation is essential in organic chemistry, as acetals are commonly used as protecting groups for carbonyl compounds.
### Detailed Explanation:
**Acetal Formation:**
1. **Start with the carbonyl compound (3-pentanone in this case) and an alcohol (ethanol).**
2. **Under acidic conditions, the carbonyl oxygen gets protonated, making it more electrophilic.**
3. **The alcohol attacks the carbonyl carbon, forming a hemiacetal intermediate.**
4. **Further reaction with another molecule of alcohol transforms the hemiacetal into an acetal.**
**Intermediates:**
- *Hemiacetal:* An intermediate compound having one -OR and one -OH group attached to the same carbon.
- *Acetal:* A compound with two -OR groups attached to the same carbon.
Thus, the formation of the acetal product involves replacing both carbonyl hydrogens with alkoxy groups (-OR) that came from the alcohol.
By understanding these steps, students](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fe92374fc-1b30-4ce3-81a2-318e4d6b8e2a%2F986e08f8-972c-44dd-bc67-ec3941bf6b98%2Frkbwofl_processed.png&w=3840&q=75)
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