Why do some reactions need to be maintained at a particular temperature for prolonged periods of time? Some reactions require that temperatures of 70–100 °C to be maintained for periods of time as long as 24 hours. Why is this so?
Quite simply, reactions happen faster at higher temperatures (because who likes waiting), and some may not proceed at all until heated. From a statistical viewpoint, you are giving more reactant molecules more energy, which thereby increases the number of collisions, which in turn increases the number of successful collisions (those which produce product). A typical way to attain such conditions is to place a reaction under reflux.