Reactions of thermal energy electrons with organic compounds

The products resulting from the reaction between electrons at thermal energy and organic compounds are studied. Thermal electrons are generated by maintaining a corona discharge in an inert gas between a stainless steel electrode and a silver-silver chloride electrode. The tested compounds, which are present as a liquid in the reaction cell, are exposed to the electron swarm at normal temperature and pressure. The identification of the reaction products by GC/MS shows that the investigated compounds react by a non-dissociative or a dissociative mechanism depending on the molecular structures. Benzaldehyde and methylbenzaldehydes, which are the conjugated electro- phores, react predominantly by a non-dissociative mechanism. The Chlorobenzaldehydes are found to react primarily by a non-dissociative mechanism but, to a minor extent, reaction products are formed through chloride dissociation. The dichlorobenzenes, simple electrophores, react predominantly by a dissociative mechanism. The strong electrophores tested, such as phthaldialdehyde and the chloronitrobenzenes, are found to be unreactive. In the case of benzaldehyde, a detailed study is presented showing the role of certain reaction parameters including the electrode geometry, the gas composition and physical properties of the test material. The study outlines why strong electron-capturing compounds which have a high or a low boiling point do not significantly react under the conditions employed. A fraction of the test material is present in the gas phase during the reaction time and the level of vapor formation can markedly affect the reaction rates. Based on the results of the study, an alternative generator of thermal electrons is proposed in order to extend the investigation of the electron-attachment reactions.