Activation of methane by gaseous platinum(II) ions PtX+ (X = H, Cl, Br, CHO)

2005 ◽  
Vol 83 (11) ◽  
pp. 1936-1940 ◽  
Author(s):  
Detlef Schröder ◽  
Helmut Schwarz
Keyword(s):  
Mass Spectrometry ◽  
Key Words ◽  
Electrospray Ionization ◽  
Gas Phase ◽  
Bond Activation ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Methane Activation ◽  
Gas Phase Reactions ◽  
Kinetic Isotope

The gas-phase reactions of methane with the platinum(II) ions PtX+ with X = H, Cl, Br, and CHO are studied by mass spectrometry. The PtX+ ions are generated by electrospray ionization of methanolic solutions of hexachloroplatinic acid and hexabromoplatinic acid, respectively. Small to moderate intramolecular kinetic isotope effects determined for the C—H(D) bond activation of CH2D2 suggest that the activation of methane by gaseous PtX+ cations is subject to thermochemical control by the product channels. In addition, the PtCl2+ cation is also able to activate methane, whereas PtCl3+ is unreactive under the conditions chosen. Key words: gas-phase reactions, mass spectrometry, methane activation, platinum bromide, platinum chloride.

Deuterium kinetic isotope effects on the thermal isomerizations of deuteriocyclopropane to deuterium-labeled propenes

2005 ◽  
Vol 83 (9) ◽  
pp. 1510-1515
Author(s):  
John E Baldwin ◽  
Stephanie R Singer
Keyword(s):  
Key Words ◽  
Gas Phase ◽  
Bond Cleavage ◽  
Isotope Effects ◽  
Reactive Intermediates ◽  
Kinetic Isotope Effects ◽  
Thermal Rearrangement ◽  
Carbon Bond ◽  
Kinetic Isotope ◽  
Carbon Carbon Bond

The gas-phase thermal isomerizations of deuteriocyclopropane to the four possible monodeuterium-labeled propenes have been followed at 435 °C. The observed distribution of products provides estimates of two deuterium kinetic isotope effects, the secondary [Formula: see text] for the carbon–carbon bond cleavage leading to trimethylene diradical reactive intermediates and the primary [Formula: see text] ratio for a [1,2] shift of a hydrogen or deuterium leading from the diradical to a labeled propene. The values determined are [Formula: see text] = 1.09 ± 0.03 and [Formula: see text] = 1.55 ± 0.06. The experimental [Formula: see text] value found agrees well with some, but not all, earlier calculated values and conjectures. Key words: cyclopropane, thermal rearrangement, kinetic isotope effects.

Oxidative dealkylation of aromatic amines by "bare" FeO+ in the gas phase

1999 ◽  
Vol 77 (5-6) ◽  
pp. 774-780 ◽  
Author(s):  
Mark Brönstrup ◽  
Detlef Schröder ◽  
Helmut Schwarz
Keyword(s):  
Gas Phase ◽  
Bond Activation ◽  
Isotope Effects ◽  
Gas Phase Reactions ◽  
Electron Transfer Mechanism ◽  
Gas Phase Chemistry ◽  
Kinetic Isotope ◽  
Phase Chemistry ◽  
Cytochrome P 450 ◽  
Mass Spectrometric Techniques

The gas-phase oxidations of aniline, N-methylaniline, and N,N-dimethylaniline by FeO+ cation are examined by using mass spectrometric techniques. Although bare FeO+ is capable of hydroxylating aromatic C—H bonds, the fate of the oxidation of arylamines is determined by docking of the FeO+ unit at nitrogen. The major reactions of the metastable aniline/FeO+ complex are losses of molecular hydrogen, ammonia, and water, all involving at least one N-H proton. N-alkylation results in a complete shift of the course of the reaction. The unimolecular processes observed can be regarded as initial steps of an oxidative dealkylation of the amines mediated by FeO+. More detailed mechanistic insight is obtained by examining the C—H(D) bond activation of N-methyl-N-([D3]-methyl)aniline by bare and ligated FeO+ species. The gas-phase reactions of FeO+ with methylanilines show some similarities to the enzymatic dealkylation of amines by cytochrome P-450. The kinetic isotope effects observed experimentally suggest an electron transfer mechanism for the gas-phase reaction.Key words: mass spectrometry, gas-phase chemistry, iron, dealkylation, N,N-dimethylaniline.

Method for Measuring Carbon Kinetic Isotope Effects of Gas-Phase Reactions of Light Hydrocarbons with the Hydroxyl Radical

2003 ◽  
Vol 107 (32) ◽  
pp. 6191-6199 ◽  
Author(s):  
Rebecca S. Anderson ◽  
Eva Czuba ◽  
Darrell Ernst ◽  
Lin Huang ◽  
Alexandra E. Thompson ◽  
...  
Keyword(s):  
Hydroxyl Radical ◽  
Gas Phase ◽  
Isotope Effects ◽  
Kinetic Isotope Effects ◽  
Light Hydrocarbons ◽  
Gas Phase Reactions ◽  
Kinetic Isotope
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