Answer to Question #71286 in Organic Chemistry for Ly Songs

Question

Separate and Purify the organic acid
1.00 g of an unknown solid mixture
9 mmol of acid in their sample.
Student drawer contents
Small filter flasks
20 mL Dichloromethane
Saturated NaHCO3
I just need to know how to set up the experiment?
1.5 M NaOH
6 M HCl
DI Water
Anhydrous MgSO4
95 % Ethanol
Hot plates
pH paper

Answer 1

Student should do the following:
1) The unknown solid mixture is treated with 1.5 M NaOH (acid dissolves).
2) The mixture is filtered and the filtrate is acidified with 6 M HCl (using the pH paper).
3) Acid is extracted with Dichloromethane (portionwise).
4) Combined extracts are dried with anhydrous MgSO4, filtered and evaporated.
5) The residue is crystallized from ethanol (maybe with adding some water - depends on the nature of acid). After cooling, the target acid is filtered, washed with ethanol (or the mixture ethanol/water) and dried.