Microflow systems compared with

Yoshida and coworkers also developed a microreaction system for cation pool-initiated polymerization [62]. Significant control of the molecular weight distribution (Mw/Mn) was achieved when N-acyliminium ion-initiated polymerization of butyl vinyl ether was carried out in a microflow system (an IMM micromixer and a microtube reactor). Initiator and monomer were mixed using a micromixer, which was connected to a microtube reactor for the propagation step. The polymerization reaction was quenched by an amine in a second micromixer. The tighter molecular weight distribution (Mw/M = 1.14) in the microflow system compared with that of the batch system (Mw/M > 2) was attributed to the very rapid mixing and precise control of the polymerization temperature in the microflow system. 

Using a micro reactor the impurity by over-alkylation was 0.18%, while the batch impurity was 1.56% [181]. This was possible due the lower back-mbdng in the microflow system. The optical purity of the microreactor product was 98.4% as compared with 97.9% at batch level. 

The pilot plant was operated smoothly without any problems for a period of 24 h to obtain 14.7 kg of the product (92% yield). It should also be emphasized that the industrial-scale production, which has been carried out using a batch reactor (10 m ), was accomplished by numbering-up only four microflow systems of the present scale. The use of microflow systems should lead to a significant decrease in investment compared with current batch process. 

A pressure-driven gas flow is generated by applying a pressure difference between the inlet and the outlet of a fluidic system, for example, a channel. Due to very small hydraulic diameters, pressure-driven gas flows in microchannels are laminar. Gas microflows are distinct from gas macroflows by rarefaction effects which appear as soon as the mean free path of the molecules is no longer negligible compared with the hydraulic diameter of the microchannel. For such rarefied flows, the classic Poiseuille model is no longer valid, and other models should be used, according to the rarefaction level, which is quantified by the Knudsen number. 

Kim, Grubbs, and coworkers reported microflow cross-methathesis of methyl oleate with ethylene [59]. The reaction in the microflow system gave the desired product in higher sdectivity compared to the reaction in bulk batch system due to the high surface area-to-volume ratio suitable for fast mass transfer of the gaseous ethylene in to the solution phase. 

Another successful application of [BMIMJIPFe] ionic liquid supported catalytic microflow reactions for Pd-catalyzed carbonylative Sonogasnira coupling of aryl iodides and phenylacetylene was reported by Rahman et al. (2006). Ionic liquid containing Pd catalysts, CO and the substrates were mixed successively, in different micromixers (channel diameter = 1 and 0.40 mm), and then pumped as a multiphase (ionic liquid-substrate-CO) into heated capillary tube reactor acting as a residence time unit (V=14.1 mL). It was found that Pd-catalyzed production of solely the acetylenic ketones in ionic liquids, when conducted in conjunction with a microreactor, preceded efficiently with superior selectivity and higher yields compared to the conventional batch system, even at low CO pressures. Authors suggested that this improvement in selectivity and yield was the result of a large interfacial... 

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