Electrochemical Reactions in Microreactors

Practical Exercise Electrochemical Reactions in Flow Microreactors 1239... 

EMM can also be effectively utihzed for fabrication of several of microfeatures for a wide range of microengineering applications such as fuel processing, aerospace, heat transfer, microfluidics, and biomedical applications. These microdevices have to often withstand high stresses at elevated temperatures during their service in different applications such as microcombustors, electrochemical reactions required at elevated temperatures in microreactors, and also in microthermal devices. For biomedical applications, microcomponents are to be made of biocompatible materials and... 

Kiipper et al. carried out a methoxylation reaction of 4-methoxytoluene in an electrochemical microreactor in which a glass carbon anode and a stainless steel cathode were separated by a microchannel foil 25 pm thick [54], The chemical resistance of the microchannel foils was very important because of the evolution of hydrogen and oxygen gases and the strong pH shifts during electrolysis. PEEK was found to be the most robust material. They also observed that selectivity of the oxidation of 4-methoxytoluene in acidified methanolic solution (pH 1, sulfuric acid) was influenced by the current density and flow rate. 

Kashiwagi [29] has successfully demonstrated that a microreactor is very efficient for the electrochemical generation of the highly unstable o-benzoquinone intermediate. The authors have reported that a two-step reaction process may be efficiently conducted by first reacting catechol (37) within the electrochemical reactor to afford o-benzoqurnone (38) in situ, before adding thiol (39) as a nucleophile, for example, to afford the product (40) in high yield (Scheme 6.13). Using a variety of thiols a library of products has been prepared in excellent yield (79-88%), whereas when the same reactions were performed in batch, yields were substantially lower (7-13%). 

Reaction System Anodic oxidation of p-methoxytoluene is carried out in the absence of intentionally added supporting electrolyte using an electrochemical flow microreactor with a serial electrode configuration to obtain p-methoxyben-zaldehyde dimethyl acetal. 

The reactions of electron-rich aromatic compounds with F generated by electrochemical oxidation of F in CH3CN also suffer from the problem of disguised chemical selectivity. The flow microreactor system incorporating a micromixer... 

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