Ryosuke Asami

A Study on Doping–Undoping Properties of Polypyrrole Films Electropolymerized under Ultrasonication

The doping-undoping properties of polypyrrole films electropolymerized under ultrasonication were investigated. p-Toluenesulfonate-doped polypyrrole film prepared with ultrasonication exhibited a more negative cathodic peak than that prepared without ultrasonication in the cyclic voltammograms. This voltammetric change at the reduction process was explained as change from the anion undoping to the cation doping. Similar voltammetric change could be also observed on the polypyrrole film doped with a large anion like 1-naphthalenesulfonate, while no voltammetric change was observed on the film doped with a small anion like ClO - 4 . Polypyrrole film polymerized in the presence of NaClO 4 showed permeability in electrochemical doping to ClO - 4 and a small anion such as Cl - , and depressed penetration of large anions such as ethanesulfonate, p-toluenesulfonate, and 1-naphthalenesulfonate into the matrix. Such an ion-sieving behavior of the polypyrrole film prepared with ultrasonication was found to be superior to that prepared without ultrasonication. Thus, the polypyrrole films electropolymerized under ultrasonication showed unique electrochemical properties in the doping-undoping processes, and these unique properties attributed to the formation of highly dense films under ultrasonication.

Development of an anodic substitution reaction system using acoustic emulsification

The anodic substitution reaction proceeded smoothly without affecting the oxidation of the nucleophile in a one-step electrochemical operation using acoustic emulsification.

A new approach to anodic substitution reaction using acoustic emulsification

We have developed a novel electrolytic system for anodic substitution reactions using acoustic emulsification. This new system involves the generation of a carbocation by anodic oxidation of a substrate, and then its reaction with a nucleophile droplet formed by ultrasonication. In this system, even if the oxidation potential of the nucleophile is lower than that of the substrate, the substrate was predominantly oxidized to give the corresponding cation intermediate because the nucleophile phase, which was insoluble in the electrolytic medium, was electro-inactive. In addition, the overoxidation of the desired products was considerably suppressed by the extraction of products from the electrolyte solution into the nucleophile phase. As a result, the anodic substitution reaction of several carbamates with allyltrimethylsilane was carried out to provide the corresponding products in good to moderate yields.