Fumihiro Amemiya

Highly clear and transparent nanoemulsion preparation under surfactant-free conditions using tandem acoustic emulsification.

A new technique for the preparation of a highly clear and transparent emulsified aqueous solution containing immiscible monomer droplets with diameters of a few tens of nanometres under surfactant-free conditions using tandem acoustic emulsification is described. Highly conductive transparent polymer films were successfully prepared from such an emulsified solution.

In situ electrogeneration of o-benzoquinone and high yield reaction with benzenethiols in a microflow system.

We have successfully demonstrated that a microflow reactor is extremely useful in controlling reactions involving an unstable o-benzoquinone. The key features of the method are an effective o-benzoquinone generation and its rapid use for the following reaction without decomposition in a microflow system.

Chemoselective reaction system using a two inlet micro-flow reactor

A new strategy for chemoselective reaction using a two inlet micro-flow reactor is described. In this system, the combined use of suitable flow mode and corresponding cathode material enables chemoselective cathodic reduction to control the product regioselectivity in carbonyl allylation.

A novel electrosynthetic system for anodic substitution reactions by using parallel laminar flow in a microflow reactor.

We have developed a novel electrosynthetic system for anodic substitution reactions by using parallel laminar flow in a microflow reactor. This system enables nucleophilic reactions to overcome the restraint, such as the oxidation potential of nucleophiles and the stability of cationic intermediates, by the combined use of ionic liquids as reaction media and the parallel laminar flow in the microflow reactor. By using this novel electrosynthetic system, the anodic substitution reaction of carbamates, especially of cyclic carbamates, with allyltrimethylsilane were carried out to provide the corresponding products in moderate to good conversion yields in a single flow-through operation at ambient temperature (without the need for low-temperature conditions).

Product selectivity control induced by using liquid–liquid parallel laminar flow in a microreactor

Product selectivity control based on a liquid-liquid parallel laminar flow has been successfully demonstrated by using a microreactor. Our electrochemical microreactor system enables regioselective cross-coupling reaction of aldehyde with allylic chloride via chemoselective cathodic reduction of substrate by the combined use of suitable flow mode and corresponding cathode material. The formation of liquid-liquid parallel laminar flow in the microreactor was supported by the estimation of benzaldehyde diffusion coefficient and computational fluid dynamics simulation. The diffusion coefficient for benzaldehyde in Bu(4)NClO(4)-HMPA medium was determined to be 1.32 × 10(-7) cm(2) s(-1) by electrochemical measurements, and the flow simulation using this value revealed the formation of clear concentration gradient of benzaldehyde in the microreactor channel over a specific channel length. In addition, the necessity of the liquid-liquid parallel laminar flow was confirmed by flow mode experiments.

Electrochemical reaction of water-insoluble organic droplets in aqueous electrolytes using acoustic emulsification

Electrochemical oxidation of water-insoluble amines (n-octylamine and n-decylamine) was successfully accomplished in aqueous electrolytes using acoustic emulsification. Acoustically prepared emulsions of fumaric acid diethyl ester in aqueous electrolytes can be also electro-reduced very smoothly. Ultrasonication to the water-insoluble organic substrate/aqueous electrolyte mixtures allowed a formation of very stable emulsions having the characteristic of giving narrow monomer droplet size distributions in the submicrometer range in aqueous electrolytes without added surfactants, and the smooth electrochemical reaction in the emulsions took place via direct electron transfer between the electrode and the water-insoluble organic droplets. In this kind of electron-transfer system, supporting electrolyte should be dissolved not only in the aqueous phase but also in the organic droplets and should contribute to the formation of an electric bilayer inside the droplets.

Self-supported paired electrosynthesis using a microflow reactor without intentionally added electrolyte

We have developed a paired electrosynthetic system using a microflow reactor. This system enables paired electrochemical reactions composed of chloride reduction/alcohol oxidation combination to progress without intentionally added electrolyte. In addition, the use of parallel laminar flow in the microflow reactor resulted in a further improvement of the desired product yields in the paired electrosynthesis.

Continuous In Situ Electrogeneration of o-Benzoquinone in Microreactor: Application to High Yield Reaction with Benzenethiols

We have successfully demonstrated that a microflow reactor is extremely useful in controlling reactions involving an unstable o-benzoquinone. As a model reaction, Michael addition reaction between o-benzoquinone generated from electrochemical oxidation of catechol and benzenethiols was employed. This reaction system enables selective oxidation of catechol avoiding the oxidation of benzenethiol, although these oxidation potentials are close to each other. The examination of several reaction conditions indicated that the key features of the method are an effective o-benzoquinone generation and its rapid use for the following reaction without decomposition in a microflow system. In addition, cyclic voltammetry measurements elucidated that catechol concentration and selection of anode material were crucial factors for effective o-quinone generation.