Reflux

Reflux is procedure by which you allow the reaction to proceed for a long period of time without losing volatile chemicals as you would if the reaction container was left open.

When you boil a pot of water, all the the water will disappear because it is converted into the gas phase. During distillation we collect the gases when then condense. During reflux, the gases produced by boiling condense and run back into the distillation pot so that all gases are maintained during this process. In theory, you could reflux a volatile chemical forever, since all gases would hit the cooled reflux column, condense and run back into the boiling flask. Using reflux a reaction can be performed for a long period of time and all volatile chemicals would be maintained.

Reactions that produce a volatile chemical or those which start with a volatile chemical are maintained in the reaction container as long as you reflux the mixture. Often, after reflux, a simple distillation can be performed to collect your chemicals for further analysis.