<P> In that context, reflux refers to the portion of the overhead liquid product from a distillation column or fractionator that is returned to the upper part of the column as shown in the schematic diagram of a typical industrial distillation column . Inside the column, the downflowing reflux liquid provides cooling and condensation of the upflowing vapors thereby increasing the efficiency of the distillation column . </P> <P> The more reflux provided for a given number of theoretical plates, the better is the column's separation of lower boiling materials from higher boiling materials . Conversely, for a given desired separation, the more reflux is provided, the fewer theoretical plates are required . </P> <P> A liquid reaction mixture is placed in a vessel open only at the top . This vessel is connected to a Liebig or Vigreux condenser, such that any vapours given off are cooled back to liquid, and fall back into the reaction vessel . The vessel is then heated vigorously for the course of the reaction . The purpose is to thermally accelerate the reaction by conducting it at an elevated temperature (i.e. the solvent's boiling point). </P> <P> The advantage of this technique is that it can be left for a long period of time without the need to add more solvent or fear of the reaction vessel boiling dry as any vapour is immediately condensed in the condenser . In addition, as a given solvent will always boil at a certain temperature, one can be sure that the reaction will proceed at a constant temperature . By careful choice of solvent, one can control the temperature within a very narrow range . The constant boiling action also serves to continuously mix the solution, although a magnetic stirring rod mechanism is often used to achieve a uniform solution . This technique is useful for performing chemical reactions under controlled conditions that require substantial time for completion . </P>

What is the point of refluxing in chemistry