With a miniaturized (3 microL volume) fiber-optics based system for on-line measurement by UV/Vis spectroscopy, the reaction rate constants (at different pressures) and the activation volumes (deltaV(not =)) were determined for a nucleophilic aromatic substitution and an aza Diels-Alder reaction in a capillary microreactor.

The pressure strength of microfluidics glass chips for high-pressure chemistry has been examined. Internal pressures up to 320 bar have been measured, although variations are substantial. Long annealing steps at high temperatures did not show any improvement, but smoothening the powder blasted channel walls by isotropic etching did. Although macro cracks are observed at the bond interface it is believed that the formation of micro cracks in the channel wall and stress concentrations due to sharp corners in the channel crosssection geometry strongly limits the maximum applicable pressures.