Mahito Atobe

Electropolymerization of pyrrole in 1-ethyl-3-methylimidazolium trifluoromethanesulfonate room temperature ionic liquid

Abstract Air and moisture stable ionic liquid like 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMICF 3 SO 3 ) has been used as an electrolyte for the electrooxidative polymerization of pyrrole; the morphological structure of polypyrrole film formed on the anode was greatly affected, and the polymerization rate, electrochemical capacity and electroconductivity were significantly increased. Furthermore, it was also found that EMICF 3 SO 3 could be recovered by a simple extraction of the remaining pyrrole monomer from the ionic liquid after use, and then reused without significant loss of reactivity for the polymerization.

Electrooxidative polymerization of aromatic compounds in 1-ethyl-3-methylimidazolium trifluoromethanesulfonate room-temperature ionic liquid

Abstract Electrooxidative polymerization of aromatic compounds such as pyrrole, thiophene and aniline was carried out in air-and moisture-stable ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMICF3SO3). The polymerization rate and morphological structure of polymer films formed on the anode were affected, and the electroconductivity was significantly increased. Furthermore, the polypyrrole film prepared in EMICF3SO3 was applied to a matrix for hosting catalyst particles electrodeposited.

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.

Anodic Oxidation on a Boron‐Doped Diamond Electrode Mediated by Methoxy Radicals

The boron-doped diamond (BDD) electrode is known to possess a wide range of applications for the direct generation of hydroxyl radicals and resulting inorganic peroxides such as persulfate, perphosphate, and hypochlorite. In contrast to the extensive use of the BDD electrode in biological and inorganic chemistry, only a few examples exist in which electrochemically generated hydroxyl or alkoxy radicals have been employed to promote reactions of highly functionalized organic substances. The known applications include reactions of relatively simple substrates, such as acetal production by oxidative C C bond cleavage, and BDD-mediated oxidative couplings to construct diaryl linkages. In general, alkoxy radicals, formed by anodic oxidation of the corresponding alcohols, function as mediators in reaction pathways that are different from those occurring under standard electrolysis conditions using carbon or platinum electrodes. Dolson and Swenton have termed reactions that proceed by the generation of methoxy radicals, formed by anodic oxidation of MeOH followed by chemical reaction of the derived radical and ionic species, as EECrCp processes. In a previous effort focusing on the synthesis of ( )-parasitenone (4) (Table 1), we have used an oxidative quantitative dimethoxy-acetalization reaction (1!2), occurring in a basic MeOH solution at a Pt electrode, as the key step (entry 1). A similarly efficient reaction takes place when the BDD electrode is employed (entry 3), while the corresponding aldehyde 3 is produced from 1 in the oxidative reaction occurring on a glassy carbon (GC) electrode (entry 2). The process taking place in a basic MeOH solution (entry 1) might involve the intermediacy of methoxy radicals in the manner described by Swenton. Similarly, reaction at the BDD electrode (entry 3) is anticipated to produce the same radical species. These observations indicated that the acetalization reaction (1!2) at Pt or BDD electrodes proceeds through the EECrCp pathway in which the initially formed arene cation radical intermediate A is converted to a cation B that undergoes addition of methoxide, while the ECEC mechanism proceeds through radical C (Scheme 1). Also, the lack of production of methoxy radicals at the GC electrode enables the initially formed cation radical A to undergo proton loss (to D) in the route for formation of aldehyde 3. Despite the plausibility of the mechanistic pathways suggested for the conversion of 1 to either 2 or 3, no studies exist providing direct proof for the involvement of radical species in processes of this type. In the current study, we have carried out ESR experiments to determine if radical intermediates are generated in electrochemical oxidation reactions of methanol using BDD, Pt, and GC electrodes. In addition, we have probed electrochemical oxidation reactions of isoeugenol (5) as part of the biomimetic preparation of the neolignan, licarin A (6). To gain information about whether or not radical species are involved in electrochemical oxidation reactions conducted in MeOH, we have carried out an ESR study using the radical trapping agent 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) (Scheme 2). Anodic oxidations of methanolic solutions of DMPO were performed employing constant Table 1: Synthesis of ( )-parasitenone (4) using anodic oxidation and electrochemical synthesis of bisketal 2.

Self-Supported Methoxylation and Acetoxylation Electrosynthesis Using a Simple Thin-Layer Flow Cell

Self-supported electrochemical methoxylation and acetoxylation of various organic molecules were carried out using a thin-layer flow cell without intentionally added supporting electrolyte. The thin-layer flow cell employed in this work had a simple geometry with working and auxiliary electrodes directly facing each other with 80 mu m distance. Controlling factors for these kinds of self-supported electrochemical methoxylation and acetoxylation, such as the electrode material, the current density, and the flow rate were optimized to allow moderate to high yields of the corresponding methoxylated and acetoxylated products to be achieved in single flow-through operations. (c) 2006 The Electrochemical Society.

Preparation of conducting polyaniline colloids under ultrasonication.

The effects of ultrasonication on the chemical polymerization of aniline leading to the formation of conducting polyaniline colloids were examined. The formation rate of the colloids was significantly increased under ultrasonication. Furthermore, it was also observed that the morphological structure of the colloids thus prepared was greatly affected by the sonication. The polyaniline colloids were further characterized by a range of techniques including electric resistance meter, gel permeation chromatography, FT-IR and cyclic voltammetry. It is noteworthy that the application of ultrasound to the polymerization resulted in a marked increase in the doping level, which reflected to the high electroconductivity of polyaniline colloids.

Characterization of transdermal solute transport induced by low-frequency ultrasound in the hairless rat skin

Sonophoretic drug transport with low-frequency (41-445 kHz) and low-intensity (60-240 mW/cm2) ultrasound was characterized using hydrophilic calcein and deuterium oxide (D2O) as a solvent vehicle in excised hairless rat skin. The excised skin was mounted in vertical diffusion chambers for measurement of skin resistance and sonophoretic transport of calcein and D2O. The calcein content of the skin was also measured after ultrasound application. When the stratum corneum (sc) side was exposed to ultrasound at an intensity of 60 mW/cm2 for 30 min, the calcein flux in the sc-to-dermis direction was increased by 22.3-, 6.3-, and 3.8-fold from a baseline of 0.0088+/-0.0100 nmol/(cm2 x h) at frequencies of 41, 158, and 445 kHz, respectively, without significant changes in skin resistance. The ultrasonically-enhanced fluxes returned to baseline following cessation of the ultrasound application. At 41 kHz, there was a further increase in the magnitude of enhancement and a significant decrease in skin resistance (by 50% of the baseline resistance) on increasing the intensity from 60 to 120 mW/cm2, whereas no further enhancement was observed at 158 and 445 kHz up to 240 mW/cm2. Comparison of the calcein content in the skin before, during, and after ultrasound application at 41 kHz, 120 mW/cm2, was consistent with a transient ultrasonically-induced increase in calcein flux. In the sonophoretic transport experiments at 41 kHz, 120 mW/cm2, calcein transport correlated well with D2O transport. When 41-kHz ultrasound was applied to the sc side at 120 mW/cm2, the calcein and D2O fluxes in the sc-to-dermis direction were 13.7- and 5.2-fold higher than those in the dermis-to-sc direction. Similar directionality was also observed in tape-stripped skin, suggesting possible induction of convection in the direction of sound propagation. However, dermal application under the same ultrasound conditions induced neither an increase in calcein and D2O transport nor a decrease in skin resistance. These results demonstrate that low frequency sonophoresis is a potentially useful technique for controlling transdermal drug transport. Convective solvent flow as well as structural alteration of the skin induced by ultrasound are likely to be responsible for the observed sonophoretic transport enhancement.

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.

Ultrasonic effects on electroorganic processes--Part 20. Photocatalytic oxidation of aliphatic alcohols in aqueous suspension of TiO2 powder.

Ultrasonic effects in a suspension system were examined using the photocatalytic oxidation of 2-propanol to acetone and of ethanol to acetaldehyde in the aqueous suspension of TiO2 powder as a model reaction. The formation rate of acetone was significantly increased under ultrasonic irradiation. The oxidation reaction under ultrasonic irradiation was affected in a different manner from that in silence by reaction conditions such as ultrasonic power, stirring speed, amount of TiO2, concentration of 2-propanol, and pretreatment of the TiO2 powder. Furthermore, it was also observed that the particle size of the TiO2 photocatalyst powder was increased due to the particle agglomeration by ultrasonic irradiation, and consequently it was suggested that ultrasound activates the surface of the catalyst. These results are discussed on the basis of not only the activation of the photocatalyst but also ultrasonic enhancement of mass transport of 2-propanol molecules.