Question

Toaccomplish the conversion which of the following reagent is most appropriate: $$ \mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCHO} \longrightarrow \mathrm{CH}_{3} \mathrm{CH}=\mathrm{CHCOOH} $$ (A) \(\mathrm{K}_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}, \mathrm{H}_{2} \mathrm{SO}_{4}\) (B) \(\mathrm{KMnO}_{4}, \mathrm{H}_{2} \mathrm{SO}_{4}\) (C) O=C([O-])c1ccccc1 (D) \(\mathrm{AgNO}_{3}, \mathrm{NaOH} ;\) subsequently \(\mathrm{H}_{3} \mathrm{O}^{+}\)

Short answer

The most appropriate reagent for the conversion of the alkene with an aldehyde group into a carboxylic acid is Option B (\(\mathrm{KMnO}_{4}\) and \(\mathrm{H}_{2}\mathrm{SO}_{4}\)).

Step-by-step solution

Write down the given reaction

The reaction involves the conversion of an alkene with an aldehyde group into a carboxylic acid: \[ \mathrm{CH}_{3}\mathrm{CH}=\mathrm{CHCHO} \longrightarrow \mathrm{CH}_{3}\mathrm{CH}=\mathrm{CHCOOH} \]

Analyze Option A

Option A suggests using \(\mathrm{K}_{2}\mathrm{Cr}_{2}\mathrm{O}_{7}\) and \(\mathrm{H}_{2}\mathrm{SO}_{4}\) as reagents. This combination is used for strong oxidation reactions, such as the conversion of primary alcohols to carboxylic acids and aldehydes to carboxylic acids. However, this reagent is not suitable for converting an alkene to a carboxylic acid directly. Therefore, Option A is not the most appropriate choice for this conversion.

Analyze Option B

Option B suggests using \(\mathrm{KMnO}_{4}\) and \(\mathrm{H}_{2}\mathrm{SO}_{4}\) as reagents. This combination is used for oxidative cleavage of alkenes to form carboxylic acids. Since our target compound is a carboxylic acid formed from an alkene, Option B seems to be the most appropriate choice for this conversion.

Analyze Option C

Option C suggests using a molecule with SMILES notation "O=C([O-])c1ccccc1" as a reagent. This molecule is benzoate anion and is not an oxidative reagent for the conversion we are seeking. Therefore, Option C is not the most appropriate choice for this conversion.

Analyze Option D

Option D suggests using \(\mathrm{AgNO}_{3}\), \(\mathrm{NaOH}\), and subsequently, \(\mathrm{H}_{3}\mathrm{O}^{+}\) as reagents. This combination is used for oxidative transformations involving halogens in organic compounds, such as the conversion of alkyl halides to alcohols or aldehydes. However, this reagent is not suitable for converting an alkene to a carboxylic acid directly. Therefore, Option D is not the most appropriate choice for this conversion.

Choose the best option

Based on the analysis of the given options, Option B (\(\mathrm{KMnO}_{4}\) and \(\mathrm{H}_{2}\mathrm{SO}_{4}\)) is the most appropriate reagent for the conversion of the alkene with an aldehyde group into a carboxylic acid.

Key concepts

Alkene Oxidation

Alkene oxidation involves the addition of oxygen to an alkene, transforming it into other types of chemical compounds such as alcohols, diols, or even acids. In organic chemistry, oxidation reactions are crucial for modifying molecules in order to enhance or change their function.
Alkenes are unsaturated hydrocarbons characterized by the presence of carbon-carbon double bonds. These double bonds are reactive sites where oxidation can occur.

• When oxidizing an alkene, different types of products can be formed depending on the reagents and conditions used.
• Oxidation can be mild or vigorous and can specifically lead to the creation of valuable compounds such as epoxides or alcoholic compounds.

Understanding alkene oxidation provides insight into the utility of alkenes as precursors to more complex organic products, invaluable in synthesis.

Oxidative Cleavage

Oxidative cleavage is a specific type of oxidation reaction and plays a crucial role in transforming alkenes by breaking carbon-carbon double bonds and replacing those bonds with double bonds to oxygen.
This process leads to the formation of oxygen-containing products like ketones, aldehydes, or carboxylic acids.
Commonly used reagents for oxidative cleavage include potassium permanganate (\(\mathrm{KMnO}_4\))in acidic or basic conditions, and ozone (\(\mathrm{O}_3\)).

• Oxidative cleavage is highly valuable because it allows for the direct transformation of hydrocarbons into more reactive and functionalized molecules.
• For example, when KMnO₄ is used under acidic conditions, alkenes can be cleaved into carboxylic acids.

This reaction mechanism is particularly useful in identifying structural elements of organic molecules and is fundamental for many synthetic pathways in chemistry.

Organic Chemistry Reagent Selection

Choosing the right reagent is a cornerstone of organic synthesis. Each reagent has specific properties and functionalities, making it more suitable for certain reactions over others.
In the conversion of the given alkene with an aldehyde functional group to a carboxylic acid, the ability of a reagent to promote oxidative cleavage is critical.

• The selection involves examining the capabilities of each reagent, like KMnO₄ for oxidative cleavages, ensuring it matches the target reaction and substrate.
• Reagent selection is not just about choosing the right reagent, but also considering reaction conditions like temperature, solvent, and time, to optimize the conversion.

Understanding the properties of reagents and how they interact with specific functional groups allows chemists to efficiently plan and execute synthetic routes, making reagent selection both an art and a science in organic chemistry.