Anelli's (TEMPO) Oxidation of alcohol by flow chemistry, industrial scale

Guy Samburski, R&D, Teva TAPI, Petach Tikva, Israel

Anelli's oxidation is used to convert an alcohol to an aldehyde in the course of manufacturing an API. This reaction occurs at a two phase system, using 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) as a catalyst (primary oxidant) and NaOCl as secondary oxidant. Further oxidation to the corresponding carboxylic acid is an undesirable by-product. Typical yield in the batch reaction is 75%, whereas main loss is due to over-oxidation. The reaction is fast and needs to be performed in -70ºC.
The reaction was performed using flow-chemistry using a 15 l/hr meso-reactor at 15 ºC. Yield increased in 15 %. Switching from batch process to flow-chemistry requires special process and technical considerations that will be discussed.