Extraction procedure and equations:
Thought I'd better post this on the current page. I need the reaction equations checked. I tried to put them in bold but can't. They should all be after Reaction:
Solid benzoic acid, p-nitroaniline and napthalene ->
Dissolve in CH2Cl2 ->
Organic layer: CHCl2 (l) + napthalene(aq)
Future aqueous layer: R-COOH(aq) + R-NH2
Add HCl. Reaction produces R-NH3+Cl- in aq. layer. Repeat extraction ->
Organic layer: CHCl2 (l) and napthalene(aq)
Aqueous layer: RNH3+Cl-(aq) and R-COOH(aq)
Reaction: R-NH2(aq) + HCl(aq) --> R-NH3(aq) + Cl-(aq)
Add NaOH to organic layer. Repeat extraction ->
Organic layer: CHCl2 and napthalene
Aqueous layer: R-COOH-Na+ and H2O
Reaction: R-COOH(aq) + NaOH(aq) --> R-COO-Na+ + H2O(l)
Recovery of each compound:
Napthalene: Wash organic layer twice. (H2O added.) ->
Organic layer: CH2Cl2 and H2O and napthalene
Add anhydrous sodium sulfate (Na2SO4) to organic layer (CH2Cl2) to dry it. ->
Reaction: Na2SO4((aq) + H2O(l) --> 2NaOH(s) + H2SO4(s)
Let CHCl2 evaporate after filtering solids to retrieve napthalene.
Add NaOH to the nitroaniline solution to neutralize. Filter and let dry. ->
Aqueous solution: NaOH and R-NH3+Cl-
Reaction: R-NH3+Cl-(aq) + NaOH(aq) -> R-NH2(s) + NaCl(aq) + H2O(l)
Add HCl to R-COO-Na+ to neutralize. Filter, wash with cold water, and let air dry.
Aqueous layer: R-COO-Na+ and HCl and H2O?
Reaction: R-COO-Na+(aq) + HCl(aq) -> R-COOH(s) + NaCl(aq)
Thanks for the help.
Sheryl
I just wrote a LONG answer to your post, which is now on page 2. You can make your comments on this page but I think I have anwered all of your questions. I hope so.
Very helpful. I have it narrowed down to a few small questions that I need to ask the lab guy. Thanks for that large effort.
Sheryl
The extraction procedure you provided involves several steps to separate and recover three compounds: solid benzoic acid, p-nitroaniline, and naphthalene. Here's a breakdown of each step and the corresponding reactions:
1. Dissolving the mixture in CH2Cl2:
- Solid benzoic acid, p-nitroaniline, and naphthalene are added to CH2Cl2 (dichloromethane).
- This step dissolves the compounds in the organic solvent CH2Cl2.
2. Organic and aqueous layer separation:
- After dissolving in CH2Cl2, the mixture forms two layers: the organic layer (CHCl2) and the aqueous layer (containing naphthalene).
- The organic layer contains CHCl2 and naphthalene.
- The aqueous layer contains benzoic acid and p-nitroaniline as ions: R-COOH (benzoic acid) and R-NH2 (p-nitroaniline).
3. Adding HCl and repeating extraction:
- HCl (hydrochloric acid) is added to the aqueous layer.
- The reaction between R-NH2 (p-nitroaniline) and HCl forms R-NH3+Cl- (p-nitroanilinium chloride) in the aqueous layer.
- Another extraction is performed, resulting in a new organic layer (CHCl2 and naphthalene) and a new aqueous layer (containing R-NH3+Cl- and R-COOH).
4. Adding NaOH and repeating extraction:
- NaOH (sodium hydroxide) is added to the organic layer.
- The reaction between R-COOH (benzoic acid) and NaOH forms R-COO-Na+ (sodium benzoate) and water (H2O).
- Another extraction is performed, resulting in a new organic layer (CHCl2 and naphthalene) and a new aqueous layer (containing R-COO-Na+ and H2O).
5. Recovery of each compound:
- Napthalene recovery:
- The organic layer (CHCl2, H2O, and napthalene) is washed twice by adding water (H2O).
- Anhydrous sodium sulfate (Na2SO4) is added to the organic layer to dry it.
- The reaction between Na2SO4 and H2O forms NaOH (sodium hydroxide) and H2SO4 (sulfuric acid).
- The CHCl2 is allowed to evaporate after filtering the solids to retrieve napthalene.
- p-nitroaniline (R-NH2) recovery:
- NaOH is added to the p-nitroaniline solution (aqueous layer) to neutralize it.
- The solution is filtered and allowed to dry.
- The reaction between R-NH3+Cl- and NaOH forms R-NH2 (p-nitroaniline), NaCl (sodium chloride), and water (H2O).
- Benzoic acid (R-COOH) recovery:
- HCl is added to the solution containing R-COO-Na+ (sodium benzoate) to neutralize it.
- The solution is filtered, washed with cold water, and then let to air dry.
- The reaction between R-COO-Na+ and HCl forms R-COOH (benzoic acid) and NaCl (sodium chloride).
These are the reactions and procedures involved in the extraction and recovery of the compounds based on the information you provided. It's always important to consult the lab technician or follow established protocols for any experimental work to ensure safety and accuracy.