What is the purpose of washing the DCM layer in the separato

What is the purpose of washing the DCM layer in the separatory funnel with sodium bicarbonate?

Solution

If you extract or wash acidic solutions with sodium carbonate or sodium bicarbonate solutions, carbon dioxide will form due to an acid-base reaction. A significant pressure will build up in the funnel. Hence, you need to be more careful in the beginning and vent more often.

If you use low boiling solvents like diethyl ether, pentane, dichloromethane, chloroform, etc. for extraction, you will observe a significant build up of pressure as well.

Due to the pressure build up, you will need to hold on to the stopper and stopcock very tightly. It might be a good idea to wrap a paper towel around the stopper and joint.

When you vent the funnel, point the stem of the funnel away from everybody, so that the solvent and gases released are not blown into somebody\'s face. The best protocol is to vent it in the back of a hood.

Never throw any layer away, until you are absolutely sure that you isolated your final product. It is easier to isolate it from a small amount of solution than from the waste container.