Textbook Question
Predict the products of the following reactions.
(g)
22. Carboxylic Acid Derivatives: NAS
Transesterification
5:20 minutesProblem 58a,b
Textbook Question
What reagents would you use to convert methyl propanoate to the following compounds?
a. isopropyl propanoate
b. sodium propanoate
Verified step by step guidance1
Step 1: To convert methyl propanoate to isopropyl propanoate, perform a transesterification reaction. Use isopropanol (isopropyl alcohol) as the alcohol reagent and an acid catalyst such as sulfuric acid (H₂SO₄) to facilitate the exchange of the methyl group with the isopropyl group.
Step 2: Heat the reaction mixture to promote the transesterification process, ensuring the methyl group is replaced by the isopropyl group to form isopropyl propanoate.
Step 3: To convert methyl propanoate to sodium propanoate, perform a saponification reaction. Use a strong base such as sodium hydroxide (NaOH) to hydrolyze the ester bond in methyl propanoate.
Step 4: During saponification, the ester bond is broken, yielding propanoic acid and methanol. The propanoic acid reacts with the sodium hydroxide to form sodium propanoate.
Step 5: Isolate the sodium propanoate by neutralizing the reaction mixture and removing any excess water or byproducts.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Transesterification
Transesterification is a chemical reaction where an ester reacts with an alcohol to form a different ester and a new alcohol. This process involves the exchange of the alkoxy group of the ester with the alcohol, which is crucial for converting methyl propanoate to isopropyl propanoate. The reaction typically requires an acid or base catalyst to proceed efficiently.
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Saponification
Saponification is the process of converting an ester into a carboxylic acid and an alcohol through hydrolysis, usually in the presence of a strong base like sodium hydroxide. In the context of the question, it is relevant for converting methyl propanoate to sodium propanoate, where the ester is hydrolyzed to yield the sodium salt of the corresponding acid.
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Reagents for Ester Reactions
The choice of reagents is critical in ester reactions. For transesterification, an alcohol (like isopropanol) is needed, while for saponification, a strong base (such as sodium hydroxide or sodium carbonate) is required. Understanding the role of these reagents helps in determining the correct pathway for the desired product transformations.
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