Question

Provide 3 reasons why refluxing is a useful technique as opposed to heating a reaction solution in a temperature bath to perform a reaction

Answer 1

Ans-(1) Many organic reactions are quite slow and need heating to achieve a reasonable reaction rate. However, most organic chemicals are quite volatile, and if heated they will evaporate and be lost. The solution to this problem is to heat the reaction mixture under reflux. This involves having the reaction mixture in a flask which is attached to a vertical, open Liebig condenser. Never attempt to stopper the Liebig condenser. "to stop the vapour escaping". If you attempt to heat sealed glass apparatus it may explode! There should be no problem with vapour escaping - as it hits the cold surface of the condenser it will condense and drip back in to the flask.

(2) the use of a hot water bath may be safer and prevent overheating, but will limit the reaction temperature to 100 ºC.The flow of cold water through the condenser should be slow.a fast flow will be more efficient in cooling, but it makes little difference, and a fast flow usually leads to floods! If vapour is escaping from the top of your condenser reduce your rate of heating.

(3) Using a gauze over the Bunsen allows the mixture to boil more smoothly. It is a good idea to use a fewanti-bumping granules in the boiling liquid.