Online Monitoring of Microwave-Enhanced Reactions by UV/Vis Spectroscopy

Microwave‐enhanced reactions are very fast in comparison to thermal reactions. They are often finished within a few minutes. Thus, the determination of the end point often fails, because conventional analytical methods are too slow. We developed a fast method using a UV/Vis sensor, which allows a direct online monitoring of the reaction process. The potency of the method is demonstrated by means of five representative reactions. Fast microwave‐enhanced reactions were monitored online by UV/Vis spectroscopy with a sensor in solution. This method is superior to slower methods (e.g. NMR, HPLC, TLC), because it is much faster and can also be performed in concentrated solutions.