Online spectroscopic investigations (FTIR/Raman) of industrial reactions: Synthesis of tributyltin azide and hydrogenation of chloronitrobenzene

The utilization of online spectroscopic methods (FTIR/Raman) for the development and the monitoring of chemical processes was demonstrated with two important chemical reaction types. The synthesis of tri-n-butyltin azide takes place at the solid-liquid interface and is therefore very sensitive to changes of reaction conditions or surface properties. Traditional offline analysis should be avoided due to the high toxicity of the compounds. The concentration variations of all involved compounds were determined. In the same way, the synthesis of 2-chloroaniline was studied to detect the formation of an unstable intermediate (the hydroxylamine) which can lead to uncontrolled decomposition reactions. Online spectroscopy is an opportunity to obtain the information about a reaction system faster and more efficiently than with conventional methods. This allows the rapid optimization of safe chemical processes and provides information for process control.