Question

Which extraction procedure will completely separate an amide from the by-product of the reaction between an amine and excess carboxylic acid anhydride?

Answer 1

Answer: A. Add 0.1M NaOH to quench unreacted anhydride. Then add diethyl ether to separate the layers. The amide can be obtained from the ether layer by evaporating the solvent.

The options are

A) Add 0.1 M NaOH to quench unreacted anhydride. Then add diethyl ether and separate the layers. The amid e can be obtained from the ether layer by evaporating the solvent

B) Add 0.1M Hal to quench unreacted anhydride. Then add diethyl ether and separate the layers. The amide can be obtained from the ether layer by evaporating the solvent.

C) Add 0.1M NaOH to quench unreacted anyhyride. Then add diethyl ether and separate the layers. The amide can be obtained from the aqueous layer by neutralizing with HCl.

Explanation:

Extraction with aqueous base will hydrolyze and extract both the acidic carboxylic acid and the excess unreacted starting material to the aqueous layer, leaving the neutral amide in the ether layer.

Answer 2

Answer: You question seems not to be complete.

Complete Question:

Which extraction procedure will completely separate an amide from the by-product of the reaction between an amine and excess carboxylic acid anhydride?

A) Add 0.1 M NaOH to quench unreacted anhydride. Then add diethyl ether and separate the layers. The amid e can be obtained from the ether layer by evaporating the solvent

B) Add 0.1M Hal to quench unreacted anhydride. Then add diethyl ether and separate the layers. The amide can be obtained from the ether layer by evaporating the solvent.

C)Add 0.1M NaOH to quench unreacted anyhyride. Then add diethyl ether and separate the layers. The amide can be obtained from the aqueous layer by neutralizing with HCl.

Explanation:The extraction procedure to use is A.

Add 0.1 M NaOH to quench unreacted anhydride. Then add diethyl ether and separate the layers. The amide can be obtained from the ether layer by evaporating the solvent

This is because the byproduct of the reaction would give an acidic carboxylic acid and unreacted starting material would also be acidic. Therefore, Extraction with aqueous base is necessary which will hydrolyze and extract both of these into the aqueous layer, leaving the neutral amide in the ether layer.