Yoshimasa Matsumura

Applications of Flow Microreactors in Electrosynthetic Processes

The fundamental advantages and potential benefits of flow microreactor technology include extremely large surface-to-volume ratios, precise control over temperature and residence time, extremely fast molecular diffusion, and increased safety during reactive processes. These advantages and benefits can be applied to a wide range of electrosynthetic techniques, and so the integration of flow microreactors with electrosynthesis has received significant research interest from both academia and industry. This review presents an up-to-date overview of electrosynthetic processes in continuous-flow microreactors. In addition, the advantages of continuous-flow electrochemistry are discussed, along with a thorough comparison of microreactor-based processes and conventional batch reaction systems.

Development of a novel electrochemical carboxylation system using a microreactor

We have developed a novel electrochemical carboxylation system for CO2 fixation to benzyl halides using a microreactor. In this system, electrochemical carboxylation of benzyl halides proceeded very efficiently without the use of a sacrificial anode such as a Mg anode to give carboxylated products in excellent yields.

Electroresponsive Structurally Colored Materials: A Combination of Structural and Electrochromic Effects

Electroresponsive structurally colored materials composed of ordered arrays of polyaniline@poly(methyl methacrylate) (PANI@PMMA) core-shell nanoparticles have been successfully prepared. The core-shell nanoparticles were synthesized by deposition of PANI shells on the surfaces of the PMMA cores by the oxidative polymerization of anilinium chloride. Ordered arrays were then fabricated by using the fluidic cell method. Because the ordered arrays and the PANI shells generate structural and electrochromic colors, respectively, these core-shell colloidal crystals exhibited colors resulting from the combined effects of these materials. The crystal colors depended greatly on the size of PANI@PMMA particles and could also be varied by the application of a voltage. The electrochromic colors of these arrays were found to be quite different from those exhibited by pure PANI films prepared by electrochemical oxidation.

Continuous in situ electrogenaration of a 2-pyrrolidone anion in a microreactor: application to highly efficient monoalkylation of methyl phenylacetate

We have successfully demonstrated effective generation of an electrogenerated base (EGB) such as the 2-pyrrolidone anion and its rapid use for the following alkylation reaction in a flow microreactor system without the need for severe reaction conditions. The key feature of the method is effective and selective preparation of monoalkylated products.

Cathodic Aromatic C,C Cross-Coupling Reaction via Single Electron Transfer Pathway

We have successfully developed a novel cathodic cross-coupling reaction of aryl halides with arenes. Utilization of the cathodic single electron transfer (SET) mechanism for activation of aryl halides enables the cross-coupling reaction to proceed without the need for any transition metal catalysts or single electron donors in a mild condition. The SET from a cathode to an aryl halide initiates a radical chain by giving an anion radical of the aryl halide. The following propagation cycle also consists entirely of anion radical intermediates.

Synthesis and molecular weight control of poly(3-hexylthiophene) using electrochemical polymerization in a flow microreactor

A new approach for the synthesis and molecular weight control of poly(3-hexylthiophene) (P3HT) using electrochemical polymerization in a flow microreactor is described. This synthetic system enabled electrochemical synthesis of soluble P3HT without its deposition using a flow microreactor. Careful selection of the reaction conditions enabled the control of molecular weight and distribution of the synthesized P3HT.

Green synthesis of α-amino acids by electrochemical carboxylation of imines in a flow microreactor

A new approach for the green synthesis of α-amino acids using electrochemical carboxylation of imines in a flow microreactor is described. This method has the major advantage of not requiring sensitive, expensive, or toxic reagents. In addition, the reaction could be conducted using single flow-through operations, without the need for sacrificial anodes and under very mild and green conditions. Our microreactor system enabled the electrochemical synthesis of N-phenylphenylglycine derivatives in good to moderate yields.

pH-Responsive Charge-Conversional and Hemolytic Activities of Magnetic Nanocomposite Particles for Cell-Targeted Hyperthermia

Magnetic nanocomposite particle (MNP)-induced hyperthermia therapy has been restricted by inefficient cellular targeting. pH-responsive charge-conversional MNPs can enhance selective cellular uptake in acidic cells like tumors by sensing extracellular acidity based on their charge alteration. We have synthesized new, pH-induced charge-conversional, superparamagnetic, and single-cored Fe3O4 nanocomposite particles coated by N-itaconylated chitosan (NICS) cross-linked with ethylene glycol diglycidyl ether (EGDE) (Fe3O4-NICS-EGDE) using a simple, one-step chemical coprecipitation–coating process. The surface of the Fe3O4-NICS-EGDE nanocomposite particles was modified with ethanolamine (EA) via aza-Michael addition to enhance their buffering capacity, aqueous stability, and pH sensitivity. The designed Fe3O4-NICS-EGDE-EA nanocomposite particles showed pH-dependent charge-conversional properties, colloidal stability, and excellent hemocompatibility in physiological media. By contrast, the charge-conversional properties enabled microwave-induced hemolysis only under weakly acidic conditions. Therefore, the composite particles are highly feasible for magnetically induced and targeted cellular thermotherapeutic applications.