Capillaries reactors

Molar ratios of bromine to m-nitrotoluene ranging from 0.25 to 1.00 were applied. The reactants were contacted in an interdigital micro mixer followed by a capillary reactor. At temperatures of about 200°C nearly complete conversion is achieved (see Fig. 6). The selectivity to the target product benzyl bromide is reasonably high (at best being 85% at 200°C and higher being 80%). The main sideproduct formed is the nitro-substituted benzal bromide, i.e. the two-fold brominated side-chain product. 

Figure 4.97 Global changes of the Belousov-Zhabotinskii reaction behavior in the capillary reactor under electrical field. (A) Reversal of the direction of the reaction zone (white stripe) propagation (0.5 mm capillary reactor) ...

Acetic acid and 10, 15, or 20% acetyl chloride were fed as a mixture into a modified falling film micro reactor (also termed micro capillary reactor in [57]) at a massflow rate of 45 g min and a temperature of 180 or 190 °C [57]. Chlorine gas was fed at 5 or 6 bar in co-flow mode so that a residual content of only 0.1% resulted after reaction. The liquid product was separated from gaseous contents in a settler and collected. By exposure to water, acetyl chloride and acetic anhydride were converted to the acid. The hydrogen chloride released was removed. 

Pure Fluid in a Non-ideal Circular Capillary Reactor... 

Biofilm Capillary Reactor Structure and Advective Transport... 

Biofilm Capillary Reactor Propagators and Residence Time Distributions... 

Reactors which generate vortex flows (VFs) are common in both planktonic cellular and biofilm reactor applications due to the mixing provided by the VF. The generation of Taylor vortices in Couette cells has been studied by MRM to characterize the dynamics of hydrodynamic instabilities [56], The presence of the coherent flow structures renders the mass transfer coefficient approaches of limited utility, as in the biofilm capillary reactor, due to the inability to incorporate microscale details of the advection field into the mass transfer coefficient model. 

Shore and coworkers [64] used a capillary reactor with a Pd thin film and microwave-assisted continuous-flow conditions for Suzttki-Miyara and Heck coupling reactions. The Pd film was prepared by passing Pd(OAc)2 solution into the 1150 pm eapillary at 150°C resulting in a highly porous catalyst composed of nanometer-size grains. 

He, P. and Heswell, S.J. and Fletcher, P.D.I. (2004). Microwave-assisted Suzuki reactions in a continuous flow capillary reactor. Applied Catalysis A General, 274, 111-114. 

The FOX assay applied to a skatole oxidation product isolated by HPLC gave a positive result, supporting the contention that it is skatolyl hydroperoxide (40) . Mixtures of 183 and the eight diastereoisomeric hydroperoxides 184 and 185 derived from thymidine (42), as shown in equation 64, can be separated and detected by RP-HPLC with UVD at 229 nm. Each isomer is determined by applying the FOX assay using a capillary reactor heated at 60 °C to provide sufficient time for total oxidation of the Fe(ll) ions, followed by UVD at 596 mn . A commercial kit based on the FOX assay for hydroperoxide determination in plasma, serum and tissue homogenizates appears in Table 2. 

Figure 11.1 Continuous cyanation using a laboratory capillary reactor.

The conversion of 2 to 3 was optimized at full scale in the VRT reactor. In addition to confirming the productivity, safety, product quality, and economic benefit of the process, the robustness of the process was also demonstrated. Finally, this pilot study provided the basis for a full-scale commercial manufacturing design specification. Having fixed the optimum residence time, the process was then transferred into a plant Fixed Residence Time (FRT) cyanation reactor which employed a fixed length of jacketed static mixer for commercial manufacture. This FRT was capable of producing 300 metric tonnes per year of 3, with the same purified step yield of 80% that was achieved in the laboratory capillary reactor. 

The EM Modular Reaction System can also be used to perform multi-step syntheses [83], For the production of pharmaceuticals, in this case for the synthesis of vitamin A, an ylid is formed from a phosphonium salt and a base in the first stage at 2 °C. In a second stage, the ylid reacts with an aldehyde at 60 °C in a flow-through capillary reactor. In a third stage the crude product is hydrolyzed at 20 °C in an additional micro mixer to form the target product vitamin A acetate, as illustrated. For the claimed reaction, no further experimental details were given. 

A slit-type interdigital micromixer was used for fast mixing [30] and compared to a tubular reactor and five Kenics mixers connected in series. Details on further components of the micromixer rig were not given, but most likely a capillary reactor was added for efficient heat exchange. 

Barton et al. (1999) briefly described their version of a plug-flow quartz capillary reactor cell. They used quartz capillaries with 0.9 mm diameter and 0.1 mm wall thickness. The heating was by a copper heat sink that was in turn heated by cartridge heaters. The quartz tube was packed with meshed particles of catalyst. 

A miniaturized protein and peptide microsequencer consisting of either a fused silica capillary reactor or a microreactor made of Teflon is described. The performance of the miniaturized sequencer was evaluated by sequencing 33 and 27 picomoles of myoglobin that were covalently attached to Sequelon-DITC. The products generated by the sequencer were analyzed using capillary electrophoresis with thermo-optical absorbance detection. This CE system provides reproducible migration time (< 0.4% of RSD) and detection limits of less than 4 fmol. 

Figure 3. Electropherograms showing the results of 33 pmol of Sequelon DITC-myoglobin by use of capillary reactor.

Suzuki-Miyaura coupling has also been conducted in a capillary reactor (400 i.m inner diameter).A commercial-scale continuous flow system consisting of a 14.5 cm x 25.4 mm column packed with Pd catalyst has also been developed. In this case, supercritical carbon dioxide is used as... 

Another example illustrating the safe operation of micro reactors at elevated temperatures and pressures was reported by Hessel et al. [25], for the industrially relevant Kolbe-Schmidt reaction (Scheme 6.8). Potassium hydrogencarbonate (31) was selected as a raw material as it is cheap and readily available, making it suitable for the industrial-scale preparation of 2,4-dihydroxybenzoic acid (32) water was selected as the reaction solvent as it is inexpensive (100-1000 lh-1). To optimize the continuous flow conditions, the authors employed a stainless-steel capillary reactor and evaluated the effect of pressure for a fixed reaction time of 6.5 min at 120 °C. 

---