Organic Reactions by Plasma-generated Reactive Species

本研究旨在制备常规电化学方法难以形成的超活性物质，并将其应用于制备有机反应。为了实现这一目标，研究了气态等离子体诱导的溶液相有机反应。1992年，利用电感耦合射频（rf）等离子体中产生的活性物质进行有机反应。芳香烯烃和炔烃在与低压氧等离子体接触的溶液中被有效氧化。用乙腈射频等离子体成功地进行了芳烃的氰化反应。1993年，用辉光放电电解（gde）方法研究了溶解在水溶液中的有机物质的氧化降解，将细线阳极浸入电解溶液中几毫米，并在电极之间施加400-450V以上的电压，以维持阳极周围稳定的辉光放电。因此，酚类物质最终被分解成二氧化碳和水。中间产物有对苯二酚、草酸盐、甲酸盐和碳酸氢盐。据推测，这种氧化作用是由水分子裂解产生的羟基自由基引起的。1994年，对gde法在有机溶剂体系中的应用进行了尝试。在乙腈中，气态产物为甲烷、乙烷、乙烯等低碳氢化合物和氰。在溶液相中，主要产物为丙腈、丙烯腈和丁二腈。提出了一种涉及离子种类（可能是乙腈阳离子）的反应方案，这种离子可以在排出区产生，并可能冲到溶液表面分解几个溶剂分子。所产生的自由基应该相互重组以产生上述产物。

In this study, the creation of super-reactive species which might be hardly formed by conventional electrochemical methods and its application to preparative organic reactions have been aimed. In order to achieve the goal, the solution-phase organic reactions induced by a gaseous plasma was investigated.In 1992, the organic reactions utilizing the reactive species generated in inductively coupled radiofrequency (rf) plasma were exploited. Aromatic alkenes and alkynes were effectively oxidized in the solution-phase in contact with a low pressure oxygen plasma. Cyanation of aromatic olefins was also successfully carried out by using the rf plasma of acetonitrile.In 1993, the oxidative degradation of organic substances dissolved in an aqueous solution was examined by means of glow discharge electrolysis (gde), where a thin wire anode was immersed into the electrolytic solution by a few mm and the voltage above 400-450V was applied between the electrodes to sustain the steady glow discharge around the anode. Thus, phenols were eventually decomposed to carbon dioxide and water. As the intermediate products, hydroquinone, oxalate and formate were found as well as bicarbonate. It was assumed that hydroxyl radical resulting from the cleavage of water molecule should be responsible for such oxidation.In 1994, the application of gde method to organic solvent system was attempted. In the gde of acetonitrile, the gaseous products were lower hydrocarbons such as methane, ethane and ethylene, and cyanogen. In the solution-phase, propionitrile, acrylonitrile and succinonitrile were obtained as major products. The reaction scheme involving the ionic species, probably acetonitrile cation, which could be generated in discharge zone and might rush into the solution surface to break up several solvent molecules, was proposed. The resulting radical species should be mutually recombined to give rise to the above-mentioned products.