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

Abstract

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.

Low energy electron induced reactions in fluorinated acetamide – probing negative ions and neutral stable counterparts*

“…This means that after closing the inlet valve some poorly defined amount of TFAA desorbed into the vacuum chamber and condensed on the substrate. However, comparing with previous thickness calibrations for other compounds [23,24] we can deduce that the layer thickness was well in the multilayer regime.…”

Electron‐Induced Hydration of an Alkene: Alternative Reaction Pathways

“…Among the C 4 hydrocarbons,t he C 2 H 4 dimer butene is the dominant product at E 0 = 15 eV. [6] This,t ogether with electron-stimulated desorption (see Figure SI2), contributes to the loss of C 2 H 4 during irradiation, as seen in Figure 1. In contrast, ethane and butane are the predominant products in the EA regime.S ignificant contributions of butene and butadiene can be excluded based on the mass peaks seen by TDS (see Figure SI3).…”

“…Together,t his supports that ethanol is in fact produced. Low-energy electrons can thus drive the formation of ethanol in mixed films of C 2 H 4 and H 2 Oa tc ryogenic temperature.Asfor the electron-induced hydroamination, [5,6] ionization of one of the reactants removes the activation barrier for the reaction. Thef ormation of ethanol thus proceeds under conditions that are fundamentally different from those of technical processes for the production of ethanol by hydration of C 2 H 4 .T hese processes require high temperatures,h igh partial pressures,a nd ac atalyst.…”

Elektroneninduzierte Hydratisierung eines Alkens: alternative Reaktionswege

“…Bei E 0 knapp oberhalb der Ionisationsschwelle ("weiche Ionisation") verläuft die Reaktion, wie im Fall der bereits beschriebenen Hydroaminierung, [5,6] über intakte Radikalkationen. Darüber hinaus wurde hier aber zum ersten Mal gezeigt, dass dasselbe Produkt auch bei E 0 unterhalb der Ionisationsschwellei mE A-Bereich gebildet wird, einem Energiebereich in dem der Abbau des gebildeten Produkts zudem noch deutlich weniger ausgeprägt ist als oberhalb der Ionisationsschwelle (Abbildung SI1 …”

“…[4] Zum Beispiel lassen sich NH 3 ,R NH 2 oder R 2 NH an die Doppelbindung von Alkenen addieren. [5,6] Solche Hydroaminierungen werden durch eine nichtdissoziative ("weiche") Elektronenstoß-Ionisation bei E 0 nahe der Ionisationsschwelle der Reaktanten ausgelçst. Hierbei wird die Abstoßung zwischen der elektronenreichen Doppelbindung und dem freien Elektronenpaar durch Ionisation eines der beiden Partner durch eine Anziehung ersetzt, die zur Bildung einer chemischen Bindung führt.…”