Microreactors - A powerful tool to synthesize peroxycarboxylic esters

The synthesis of peroxycarboxylic esters, as one subgroup of organic peroxides, is characterized by a high thermal hazard potential regarding process safety. In case of failure in the production process, e. g., if the heat of reaction cannot be removed sufficiently fast, decomposition reactions can be triggered, and as a result, remarkable amounts of heat and gas can be released and can cause a high extent of damage. Multifarious technical and organizational measures are necessary to ensure the safe industrial production of peroxides. With the introduction of microreaction technology plenty of possibilities have been opened to carry out highly exothermic reactions in smaller volumes and with more efficient heat removal. In this paper we report the application of three different microstructured reactors, representing different mixing strategies, to synthesize two peroxymonocarboxylic esters, namely tert- butyl peroxypivalate and tert- butyl peroxy- 2- ethylhexanoate. The following reactor types were considered: an orifice microreactor, a split and recombine microreactor and a capillary tube reactor in combination with ultrasonication. The efficiency of the two phase liquid/ liquid reaction is expressed in comparison of conversion and selectivity. With microreaction technology a remarkable increase in space- time- yield, ranging from 12,500 kg center dot m(-3) center dot h-1 to 414,000 kg center dot m-3 center dot h-1, is achieved.