Low-Energy Electron-Induced Hydroamination Reactions between Different Amines and Olefins

Thermal desorption spectrometry (TDS) was applied to investigate reactions initiated by electron exposure of multilayer condensed films containing both an olefin and an amine or ammonia. In all cases, electron-induced hydroamination reactions leading to addition of ammonia or an amine to the C=C double bond of the olefin were detected. The dependence of the hydroamination product yield on the electron energy was studied for mixtures of ethene with ammonia, ethylamine, and diethylamine and points, in all three cases, to an ionization-driven process. Concurrent reactions include the formation of larger hydrocarbons as well as fragmentation of the reactants and, in particular, of the amines so that higher substituted analogues are obtained even without the presence of an olefin. The mechanisms of these reactions are reviewed and an ionization-driven olefin dimerization is proposed that closely resembles the previously described hydroamination. The results underline the general concept of electron-induced synthesis driven by ionization but also demonstrate how the complexity of the reactions increases as the reactants become larger.