Heat flow reaction calorimetry under reflux conditions. Thermochimica Acta

A brief review of the procedures used in heat flow reaction calorimetry experiments under reflux and their evaluation is presented. A method to calibrate global heat transfer coefficients and the mass flow of the cooling condenser fluid under refluxing conditions is validated and discussed through experiments with pure solvents. A study of the influence of the most significant experimental conditions on the accuracy of the measurements is also considered. 1. INTRODUCTI3N One of the most suitable designs of reaction calorimeters [l] for the study of industrial chemical processes is that proposed by Regenass [2] and commercialised by Mettler under the name of RCl. This is a heat flow reaction calorimeter which requires the evaluation of the global heat transfer coefficient through the reactor wall in order to calculate the heat flow. This determination is called calibration and is accomplished through the injection of a known thermal power into the system. Most of the papers published on reaction calorimetry examine reaction mixtures of pure solvents at temperatures below their boiling point. However, in organic synthesis a significant number of processes are performed under refluxing conditions. In 1988, Steele and Nolan [3] introduced the use of a set of accessories which allows the heat from the solvent condensation in reflux experiments to be measured and which reduces the heat losses that are more significant under these conditions than when the reaction temperature is far below boiling point. In 1989, Mettler introduced reflux and distillation accessories that do * Corresponding author