Electron bombardment flow reactor

The above experiments are generally difficult to perform and the interpretation of the results may not necessarily be straightforward. The low abundance of the neutral products collected and the likelihood of mass spectral interference between reagents and products make these techniques applicable only to special cases. An independent approach to this problem has been proposed by Marinelli and Morton (1978) who have used an electron-bombardment flow reactor allowing in principle for larger collection of neutral products followed by glc and mass spectral analysis. 

Further support for the idea that cationic nucleophilic displacement occurs with inversion of configuration has been advanced by Hall et al. (1981). The study of reaction (55) in an electron-bombardment flow reactor at reagent pressures below 10 3torr, followed by neutral product analysis (Marinelli and Morton, 1978), reveals that these reactions also occur via backside attack. This is in disagreement with the original suggestion of Beauchamp et al. (1974) who proposed a frontside displacement in the case of t-butyl alcohol. 

Ring closure of nascent CH2=CHCH2CH2CHf within ion-neutral complexes has been studied using a specially designed Electron Bombardment Flow (EBFlow) reactor, schematically drawn in Figure 3. This apparatus has the advantage that the conditions under which ions are formed and react (70 eV electron impact pressure <0.001 mbar) closely parallel those in mass spectrometer sources. The neutral product yields are routinely interpreted with reference to the ionic products observed by the mass spectrometry. Hypotheses based on EBFlow results for ion neutral complexes are further tested by comparison with mass spectrometry. 

Figure 3, Schematic of an Electron Bombardment Flow (EBFiow) reactor. The magnetic field maintains the electron beam along the axis of the solenoid. The beam s negative charge prevents cations from migrating to the walls, and all charged species are dumped into the differentially pumped region downstream of the clown cap, where they are pumped away and do not contaminate the neutrals collected in the cold trap, which come from the EBFiow reaction vessel.

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