Organic Reaction: CrO3/HOAc Breakdown of R-CH=CH-C=_CH

In summary, the purpose of using CrO3/HOAc in the breakdown of R-CH=CH-C=_CH is to oxidize the carbon-carbon double bond (C=C) and triple bond (C≡C) in the molecule. This occurs through a process called oxidative cleavage, where the bonds are broken down into two carbonyl (C=O) groups. The reaction mechanism involves the initial attack of CrO3 on the double or triple bond, followed by hydrolysis to form the carbonyl groups. The products of the reaction are two separate carbonyl groups, which may vary depending on the starting molecule. Precautions should be taken when handling CrO3, as it is a
  • #1

Homework Statement



R-CH=CH-C=_CH in presense of CrO3 and HOAc gives R-COOH+ CH=_C-COOH



The Attempt at a Solution



Can someone please explain this reaction to me? Seems like the double bond was broken and replaced with a =O. Almost like ozonolysis except the triple bond wasnt touched.
 
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  • #3


The reaction you have described is known as the Jones oxidation, which is a common organic reaction used to convert alkenes (R-CH=CH-R) to carboxylic acids (R-COOH). In this reaction, the chromium trioxide (CrO3) acts as an oxidizing agent, while the acetic acid (HOAc) serves as a solvent and proton source.

The first step of the reaction involves the formation of a chromate ester intermediate, where the chromium atom is attached to one of the carbon atoms in the double bond. This intermediate is then attacked by a water molecule, leading to the formation of a chromate ester with a hydroxyl group attached to the chromium atom. This hydroxyl group is then protonated by acetic acid, forming a chromic acid (H2CrO4) intermediate.

The chromic acid intermediate then reacts with the other carbon atom in the double bond, leading to the formation of a carboxylic acid functional group. This reaction involves the cleavage of the double bond and the formation of a carbonyl group (C=O). The final product is a carboxylic acid with the same carbon chain as the original alkene.

Overall, the Jones oxidation is a useful reaction for converting alkenes to carboxylic acids, which are important functional groups in organic chemistry. It is important to note that this reaction only works for alkenes with at least one hydrogen atom attached to the carbon atoms in the double bond. Alkenes with no hydrogen atoms (such as alkynes) will not undergo this reaction.
 

1. What is the purpose of using CrO3/HOAc in the breakdown of R-CH=CH-C=_CH?

The purpose of using CrO3/HOAc is to oxidize the carbon-carbon double bond (C=C) and the carbon-carbon triple bond (C≡C) in the R-CH=CH-C=_CH molecule.

2. How does the CrO3/HOAc reaction occur?

The CrO3/HOAc reaction occurs through a process called oxidative cleavage, where the carbon-carbon double bond (C=C) and the carbon-carbon triple bond (C≡C) are broken down into two separate carbonyl (C=O) groups. This is achieved by the CrO3 oxidizing the double or triple bond, while the HOAc acts as a solvent and proton source.

3. What is the mechanism of the CrO3/HOAc reaction?

The mechanism of the CrO3/HOAc reaction involves the initial attack of the CrO3 on the carbon-carbon double or triple bond, forming a cyclic intermediate with the oxygen atom of the CrO3. The intermediate then undergoes hydrolysis, breaking the bond between the two carbons and forming two separate carbonyl groups.

4. What are the products of the CrO3/HOAc reaction?

The products of the CrO3/HOAc reaction are two separate carbonyl (C=O) groups. The specific products will depend on the starting molecule and the position of the double or triple bond within the molecule.

5. Are there any precautions to take when performing the CrO3/HOAc reaction?

Yes, it is important to handle CrO3 with caution as it is a strong oxidizing agent and can cause skin and eye irritation. It should also be handled in a well-ventilated area as it can release toxic fumes. Proper protective gear, such as gloves and goggles, should be worn when handling CrO3. Additionally, the reaction should be performed in a fume hood to minimize exposure to the fumes.

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