Reaction Monitoring by Benchtop NMR Spectroscopy Using a Novel Stationary Flow Reactor Setup

A flow reactor setup for noninvasive monitoring of reactions using a compact benchtop nuclear magnetic resonance (NMR) spectrometer is presented, in which a tubular flow reactor is inserted into the bore of the NMR spectrometer and operated at stationary conditions. To monitor the composition change of the reaction mixture in the flow reactor, the entire reactor is moved to different longitudinal positions in the bore. As the flow is stationary, the composition of the reaction mixture does not change with time at a fixed reactor position. Thus, also time-consuming 2D NMR techniques can be applied to elucidate unknown products. As quantitative information is obtained directly from the NMR spectrum without calibration, the method is also appropriate for quantifying substances that are unstable as pure components. As test cases, two esterification reactions, the formation of methyl formate and the formation of methyl acetate from the pure alcohols and acids, were investigated using this technique. In addition, three 2D NMR pulse sequences (H–H–COSY, HETCOR, and HMBC) were applied in flow. The comparison of the results of the present work to literature data shows that the new method gives reliable results.

Miniemulsion photopolymerization in a continuous tubular reactor: particle size control via membrane emulsification

Synthesis of polymeric nanoparticles of adjustable size in the submicron-range 200–950 nm has been conducted via membrane emulsification combined with photoinduced miniemulsion polymerization in a continuous tubular flow reactor.

New Insights into the Kinetics of the Gas-Phase Oxidation of Hexafluoropropene

The gas-phase reaction of hexafluoropropene and molecular oxygen was investigated in a tubular flow reactor at 450 kPa and within a temperature range of 463–493 K using HFP/O2 mixtures containing 20–67% HFP on a molar basis. Capillary and packed column chromatography served as the main analytical technique. The reaction yielded HFPO, COF2, CF3COF, C2F4 and c-C3F6 as gas-phase products. High molecular weight oligomers were also formed. The oligomers were found to have a polyoxadifluoromethylene structure according to elemental and 19F NMR analysis. At 493 K HFP is proposed to undergo oxygen-mediated decomposition to difluorocarbene radicals, yielding greater quantities of difluorocarbene recombination products. Kinetic parameters for a revised model of the oxidation process were identified through least squares analysis of the experimental data.

Decomposition studies of group 6 hexacarbonyl complexes. Part 1: Production and decomposition of Mo(CO)6 and W(CO)6

Chemical studies of superheavy elements require fast and efficient techniques, due to short half-lives and low production rates of the investigated nuclides. Here, we advocate for using a tubular flow reactor for assessing the thermal stability of the Sg carbonyl complex – Sg(CO)