Organic Reactions by Plasma-generated Reactive Species

本研究的主要目的是创造常规电化学方法难以形成的超活性物种，并将其应用于制备有机反应。为了实现这一目标，人们对气相等离子体诱导的液相有机反应进行了研究，1992年，利用感应耦合射频（rf）等离子体中产生的活性物种进行的有机反应得到了开发。在低压氧等离子体作用下，芳香族烯烃和炔烃在液相中被有效地氧化。在1993年，用辉光放电电解（gde）研究了溶解在水溶液中的有机物的氧化降解，其中将细线阳极浸入电解液中几mm，电压高于400 - 400V。在电极之间施加450V以维持阳极周围的稳定辉光放电。因此，酚类最终分解为二氧化碳和水。中间产物有对苯二酚、草酸盐、甲酸盐和碳酸氢盐。1994年，有人尝试将gde方法应用于有机溶剂体系，认为水分子裂解产生的羟基自由基是这种氧化反应的原因。在乙腈的裂解过程中，气相产物为甲烷、乙烷、乙烯等低级烃类和氰。在液相中，得到丙腈、丙烯腈和丁二腈作为主要产物。提出了在放电区产生的离子物种（可能是乙腈阳离子）可能冲入溶液表面分解多个溶剂分子的反应方案。所产生的自由基物种应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.