why did we wash the ether solution of the product with 10% hydrochloric acid?
The correct answer and explanation is:
Washing an ether solution of a product with 10% hydrochloric acid is a common step in organic chemistry workups to remove basic impurities, such as amines or residual basic reagents. The purpose of this acid wash is to convert any basic impurities into their corresponding water-soluble salts, which then separate from the organic layer.
When the ether solution contains basic compounds, they tend to remain dissolved in the organic phase. Adding hydrochloric acid protonates these bases, forming ammonium salts or other protonated species. These salts are ionic and highly soluble in the aqueous layer. During the washing process, the mixture is shaken or stirred so that the aqueous acid phase extracts these protonated impurities from the organic ether phase. After settling, the two layers separate due to their different densities and polarities, with the aqueous layer containing the unwanted basic impurities and the organic layer retaining the desired neutral product.
This procedure is especially useful for removing leftover amines, which are common in organic synthesis. For example, if a reaction used a basic catalyst or amine reagent, traces could remain dissolved in the ether solution. Washing with hydrochloric acid ensures these amines become water-soluble ammonium salts and are removed efficiently.
Additionally, this acid wash can help remove some metal contaminants that form water-soluble complexes in acidic conditions. The product in the ether layer remains largely unaffected because most neutral organic compounds do not react or dissolve in dilute aqueous acid.
After the acid wash, the organic layer is typically washed with water or a base wash to neutralize any remaining acid, dried over a drying agent to remove water, and then concentrated to isolate the pure product.
In summary, washing the ether solution with 10% hydrochloric acid removes basic impurities by converting them into water-soluble salts, thereby purifying the desired organic product. This step improves the overall purity and yield of the final compound.