The working principle of 20L high borosilicate double jacketed glass reactor is: through the sandwich of the double reactor, high or low temperature (heating or cooling) circulation liquid is injected, and the material in the reactor is heated or cooled at constant temperature, and the material is reacted (decomposed and combined) in the reactor. And can control the reaction bath evaporation, reflux and collection speed, after the reaction is completed, the remaining in the kettle from the bottom of the kettle discharge port, the operation is very convenient.