Parameter optimisation of a microreactor based continuous synthesis of bromooctyl glucoside by Fischer glycosylation

Bromalkyl glycosides are promising molecules for use as functionalised spacers in the production of glycomimetics. The here presented optimised process can serve as the basis for the technical synthesis of bromoalkyl glycosides in a microreactor. Therefore, we tested the influence of residence time and temperature on the synthesis of bromoalkyl glycosides in a microreactor. To determine the optimum temperature, the synthesis was investigated between 90 °C and 150 °C, in 10 °C increments. To determine the optimum residence time in the reactor, the residence time was varied between 1 and 10 min. The results show, that the product yield increases initially with increasing temperature or residence time. In both curves, there is limited growth before the yield drops again after the peak. It was found that at high temperatures and residence times, the number of undesirable by-products may also increase, which has a negative effect on product yield. We found the optimum temperature range is 120 °C-130 °C and the optimum residence time at 7.5 min.