Suppose you have just synthesized heptanoic acid from heptan-1-ol. The product is contaminated by sodium dichromate, sulfuric acid, heptan-1-ol, and possibly heptanal. Explain how you would use acid–base extractions to purify the heptanoic acid. Use a chart, like that in Figure 20-3, to show where the impurities are at each stage.
The solubility properties of acids and their salts may be used to remove nonacidic impurities.A carboxylic acid is more soluble in the organic phase, but its salt is more soluble in theaqueous phase. Acid?base extractions can move the acid from the ether phase into a basicaqueous phase and back into the ether phase, leaving impurities behind.