Microreactor batch

Entry Concentration (M) Time Microreactor Batch Microreactor Batch... 

Viable operating eonditions were identified experimentally for maximising the produetion of ethylene, propylene, styrene and benzene from the pyrolysis of waste produets. Data are given for pyrolysis temperature, produet reaetion time, and quench time using a batch microreactor and a pilot-plant-sized reactor. 26 refs. CANADA... 

The Microreactor a systematic and efficient tool for the transition from Batch to Continuous Process Chem. Eng. Res. Des., 84 (5), 363-369. 

Temperature profile of the phenyl boronic acid synthesis along the major steps of the process flow scheme. The difference in the temperatures of the conventional batch and the microreactor processes stand for the reduction in energy consumption and respective heat-transfer equipment when using the latter [10]... 

In this way, the operational range of the Kolbe-Schmitt synthesis using resorcinol with water as solvent to give 2,4-dihydroxy benzoic acid was extended by about 120°C to 220°C, as compared to a standard batch protocol under reflux conditions (100°C) [18], The yields were at best close to 40% (160°C 40 bar 500 ml h 56 s) at full conversion, which approaches good practice in a laboratory-scale flask. Compared to the latter, the 120°C-higher microreactor operation results in a 130-fold decrease in reaction time and a 440-fold increase in space-time yield. The use of still higher temperatures, however, is limited by the increasing decarboxylation of the product, which was monitored at various residence times (t). 

Metal-catalyzed cross-couplings are key transformations for carbon-carbon bond formation. The applicability of continuous-flow systems to this important reaction type has been shown by a Heck reaction carried out in a stainless steel microreactor system (Snyder et al. 2005). A solution of phenyliodide 5 and ethyl acrylate 6 was passed through a solid-phase cartridge reactor loaded with 10% palladium on charcoal (Scheme 2). The process was conducted with a residence time of 30 min at 130°C, giving the desired ethyl cinnamate 7 in 95% isolated yield. The batch process resulted in 100% conversion after 30 min at 140°C using a preconditioned catalyst. 

There are many reasons why chemical synthesis is advantageously performed in flow mode using a micro-contactor (or microreactor) rather than in a round-bottomed flask, well or vessel. In fact, if it was not for a long history of batch mode chemistry and the convenience of a handsized flask, the case would need to be made for employing batch methods. 

Overall, the microreactor provides greater safety for individuals and equipment and reduces the likelihood of loss of process and the consequent disruption and even loss of sales that can follow. In common with other fine chemical manufacturers, most pharmaceutical companies have programs to capture the benefits of flow microreactors as adjuncts to or even replacements for their current batch methods for scaling up production of candidate molecules to satisfy clinical and manufacturing needs. This paper attempts to demonstrate that microreactors can be deployed more widely in pharmaceutical R D than as a tool for enhanced production and that they have the potential to underpin significant paradigm shifts in both early- and late-phase R D. 

The microreactor shown in Fig. 1 can be regarded as a continuous-flow reactor equivalent to the common batch reactor flask. The microreactor has a mixer section that provides more precise mixing characteristics than those typically achievable in a stirred vessel. For example, in the... 

The much larger rates of heat transfer in microreactors allow highly exothermic reactions that are difficult to control in conventional batch systems, such as direct fluorination (Chambers and Spink 1999 Jah-nisch et al. 2000 de Mas et al. 2003) and ozonolysis (Wada et al. 2006). Thus, microreactors expand the number of possible reactions and feasi-... 

Fig. 5. Earnings and total costs for a commercial microreactor process, for the real-life micro-flow case, three processes intensified or numbered-up microflow cases, and a batch benchmark case (Courtesy of Swiss Chemical Society)...

A significant improvement in the conduction of this reaction was reported under microflow conditions in comparison with batch mode. Batch conditions involved a reaction time of 60 h at room temperature to afford the final product in a 62% yield. Under optimized microreactor conditions, the online HPLC-determined yield was 91 % in a 60 min reaction time (Scheme 2). Note that the microreactor setup allowed the reaction temperature to be higher than the atmospheric boiling point of the solvent. 

Ruy et al. have performed a similar reaction under microreactor conditions in a multiphase solvent system containing an ionic liquid as the catalyst carrier and reaction promoter [35]. Their system consisted of two T-shaped micromixers (i.d. 1,000 and 400 pm) and a capillary stainless steel tube as an RTU (1,000 pm i.d. and 18 m length, giving a 14.1 ml volume), equipped with pumps and control valves. Under the optimized conditions, Pd-catalysed carbonylation of aromatic iodides in the presence of a secondary amine provided only the double carbonylated product, ot-ketoamide, while the amide obtained by the single carbonylation was observed in high quantities only when the reaction was performed in batch (Scheme 13). 

The miniaturized conditions provided a suitable setting for this reaction, affording several important benefits. First, in microreactor environment this highly exothermic process demanded no additional cooling, whereas the reaction in batch needs to be conducted at 0°C. In addition to this, instant TOF-MS analysis proved the formation of the nitrilium cation intermediate, thus proving the reaction mechanism that was speculative until then. Another advantage of the reactor directly connected to the analyzer is the convenience and the speed of the reaction optimization. 

Yoshida et al. [63] applied microreaction technology for the sequential synthesis and the disubstitution of o-bromophenyUithiuni (Scheme 28). Lithiation of o-dibromobenzene in batch leads to the formation of the highly reactive benzyne and to the further creation of various side products thus this reaction needs to be conducted at 100°C and below to avoid this problem. This reaction was optimized under microreactor conditions for the production of o-bromophenyUithium and for its further reaction with methanol to determine the yield of bromobenzene. Microreactors were set up of stainless steel tubes with an internal diameter of 250-1,000 pm. 

Struempel M, Ondruschka B, Stark A (2009) Continuous production of the diazomethane precursor N-methyl-N-nitroso-p-toluenesulfonamide batch optimization and transfer into a microreactor setup. Org Process Res Dev 13(5) 1014—1021... 

Now we shall discuss the method used to calculate the "cup"-averaged MWD-H, in which all portions of a polymerized liquid are mixed and averaged in a "cup" (vessel) positioned after the reactor. In this analysis, recourse was made to the so-called "suspension" model of a tubular reactor. According to this model, the reaction mass is regarded as an assemblage of immiscible microvolume batch reactors. Each of these microreactors moves along its own flow line. The most important point is that the duration of the reaction is different in each microreactor, as the residence time of each microvolume depends on its position at any given time, i.e., on its distance from the reactor axis. 

The PDMS-E described in the batch studies was used to mold reactors. These microreactors were fed the same 0.1 M urea solution as used in batch experiments. Reactors were operated for approx 1 hbefore acquiring operational data to reduce the effects of any loosely bound enzymes that may wash out from the surfaces of the microchannel walls. 

Microreactors for long single reactions Semi-batch systems including valves... 

Microreactors for multiple parallel reactions, either fast or long Semi-batch systems similar to titer-plates connected to microdispensing systems and separation/analysis units... 

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