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

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.

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.

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g

the answer is option a.