DEVELOPMENTAL RESEARCH ON LASER-INDUCED SYNTHETIC REACTIONS

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Laser induced reactions are expected to be adopted in industrial synthetic processes, particularly for producing a certain kind of specific chemicals with a high selectivity. However, the important concern is the high laser-photon cost. The present research aims at the development of certain chain reactions. The synthetic process of vinylidene chloride from 1,1-dichloroethane through a chlorination followed by a dehydrochlorination reaction, and the partial oxidation process of cyclohexane have been studied.In the former system, the reaction was started by irradiation of 1,1-dichloroethane in the presence of chlorine with a XeF excimer laser. The photo-dissociated atomic chlorine playd as a chain-charrier, and 1,1,1-trichloroethane was produced with a long chain length. In the subsequent step, the trichloroethane was dehydrochlorinated with a relatively high chain length to yield vinylidene chloride. Thus by combining the above two steps, a novel synthetic process of vinylidene chloride was established.Concerning the partial oxidation of cyclohexane, the following results were obtained. The liquid phase cyclohexane with dissolved oxygen absorbed the KrF excimer laser light and the laser-induced oxidation reaction proceeded to yield cyclohexanol and cyclohexanone. However, the reaction progress in the present system was controlled by radical-radical reactions in the solvent cage, and thus the chain length was not sufficiently long.Generally speaking, the chain length could be elongated to a high enough extent in many reaction systems, so that the laser-induced reactions may be adopted in practical systems. Many reaction systems are expected to be developed in future.