ISSN:
0951-4198
Schlagwort(e):
Chemistry
;
Analytical Chemistry and Spectroscopy
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Physik
Notizen:
A systematic comparison of the reactivity of the γ-dictonic ion ·CH2CH2CH2C≡O+ to that of its even-electron analog, CH3CH2CH2C≡O+, and a related conventional radical cation, ionized cyclopentanone, was carried out using a dual-cell Fourier-transform ion cyclotron resonance mass spectrometer. Each of the ions exhibits unique chemical reactivity. The conventional radical cation reacts with neutral reagents primarily by electron transfer. The even-electron acylium ion CH3CH2CH2C≡O+ is unreactive towards most of the neutral molecules studied; slow proton transfer is the only reaction observed with a few reagents. In sharp contrast to the behavior of these two ions, the distonic ion undergoes a variety of reactions with each neutral reagent. Most of these reactions involve a homolytic bond cleavage in the neutral reagent, leading to abstraction of an atom or a radical by the ion. Although reactions directly involving the charge site are not common for this ion, many of its reactions are likely to be catalyzed by the charge site. Initial bond formation at the charge site stabilizes the collision complex, extending its lifetime. This binding may also favorably position the neutral molecule for a subsequent reaction with the radical site of the ion. Accordingly, relatively facile radical abstraction reactions were observed for those reagents which react through a favorable six-membered transition state after bonding to the charge site. These neutral reagents react similarly, but at a slower rate, with the lower homolog, ·CH2CH2C≡O+, presumably because a six-membered transition state is not accessible in this case.
Zusätzliches Material:
4 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/rcm.1290070516
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