An ICR mass spectrometry study of ion/molecule reactions between ethyl chloride and alkylamines

1991 ◽  
Vol 69 (2) ◽  
pp. 363-367
Author(s):  
Guoying Xu ◽  
Jan A. Herman
Keyword(s):  
Mass Spectrometry ◽  
Key Words ◽  
Rate Constant ◽  
Rate Constants ◽  
Ethyl Chloride ◽  
Ion Molecule Reactions ◽  
Mass Spectrometry Study ◽  
Ethyl Cation

Ion/molecule reactions in mixtures of ethyl chloride with C1–C4 alkylamines were studied by ICR mass spectrometry. Ethyl cation transfer to C1–C4 alkylamines proceeds mainly through diethylchloronium ions with rate constants ~3 × 10−10cm3 s−1. In the case of s-butylamine the corresponding rate constant is 0.5 × 10−10 cm3 s−1. Key words: ICR mass spectrometry, ion/molecule reactions, ethylchloride, methylamine, ethylamine, propylamines, butylamines

An ICR mass spectrometry study of ion/molecule reactions in mixtures of methylamine with ethylamine, propylamine, or butylamine

1990 ◽  
Vol 68 (4) ◽  
pp. 570-574 ◽  
Author(s):  
Guoying Xu ◽  
Jan A. Herman ◽  
Leszek Wójcik
Keyword(s):  
Mass Spectrometry ◽  
Numerical Simulation ◽  
Rate Constants ◽  
Bimolecular Reactions ◽  
Methyl Group ◽  
Group Transfer ◽  
Ion Molecule Reactions ◽  
Mass Spectrometry Study ◽  
Ion Species ◽  
Methyl Group Transfer

Ion/molecule reactions of protonated alkylamine ion species, RNH3+, were studied in mixtures of methylamine with ethylamine, propylamine, or butylamine by ICR mass spectrometry at 10−5 Torr. The occurrence of methyl group transfer from methylamine to higher protonated alkylamine ion species was observed. The rate constants of some bimolecular reactions occurring in these systems were estimated by numerical simulation. Keywords: ion/molecule reactions, methylamine, ethylamine, propylamine, butylamine, ICR mass spectrometry.

Ion/molecule reactions in allene. III. Reactions of the parent ion with neutral alkanes

1986 ◽  
Vol 64 (1) ◽  
pp. 192-197
Author(s):  
Kenzo Nagase ◽  
Jan A. Herman
Keyword(s):  
Mass Spectrometry ◽  
Rate Constants ◽  
Relative Rate ◽  
Transfer Reactions ◽  
Stabilization Process ◽  
Transfer Processes ◽  
Ion Molecule Reactions ◽  
Relative Rate Constants ◽  
Ion Species

Ion/molecule reactions between the ion C3H4+• ion, from allene and neutral alkanes were investigated by mass spectrometry. There are four H•/CH3•/H−/H2− transfer reactions and relative rate constants were calculated. The overall rates increased in the order CH4 < C2H6 < C3H8 < i-C4H10 < n-C4H10. There is also a stabilization process by alkanes of CeH8+• ion species, but its importance is lower than the above transfer processes.

C(2)-H isotopic exchange in coordinated imidazoles revisited. The case of the [Co(NH3)5ImH]3+ ion

1999 ◽  
Vol 77 (2) ◽  
pp. 178-181 ◽  
Author(s):  
Charles R Clark ◽  
Allan G Blackman ◽  
M Ross Grimmett ◽  
Akbar Mobinikhaledi
Keyword(s):  
Metal Complex ◽  
Temperature Dependence ◽  
Key Words ◽  
Rate Constant ◽  
Rate Constants ◽  
Isotopic Exchange ◽  
Ionization Constant ◽  
Ionization Constants ◽  
First Order ◽  
Acid Ionization

The temperature dependence of the acid ionization constants of [Co(NH3)5ImH]3+ in H2O (I = 1.0 M (NaClO4)): pKa (°C) = 10.10 ± 0.04 (25.0), 9.92 ± 0.03 (30.0), 9.82 ± 0.02 (35.0), 9.62 ± 0.03 (40.0), and [Co(ND3)5ImD]3+ in D2O (I = 0.35 M (NaClO4)): pKa (°C) = 10.58 ± 0.06 (25.0), 9.46 ± 0.08 (60.0) is reported. Observed first-order rate constants for H/D exchange at C-2 in [Co(ND3)5ImD]3+ over the pD range 8.08-11.20 (60.0°C, I = 0.35 M (NaClO4)) follow an equation of the form: kobs = kODKw/(aD+ + Ka)γ±, with kOD (0.27 ± 0.06 M-1 s-1) corresponding to the rate constant for OD--catalyzed abstraction of H-2 in [Co(ND3)5ImD]3+, and Ka ((2.8 ± 0.7) × 10-10 M, pKa = 9.55 ± 0.13) to the acid ionization constant of this species. No evidence was found for a pathway to H/D exchange in the imidazolate moiety of [Co(ND3)5Im]2+.Key words: kinetics, H/D-exchange, imidazole, metal complex.

scholarly journals Hyperoxidation of Peroxiredoxins 2 and 3

2013 ◽  
Vol 288 (20) ◽  
pp. 14170-14177 ◽  
Author(s):  
Alexander V. Peskin ◽  
Nina Dickerhof ◽  
Rebecca A. Poynton ◽  
Louise N. Paton ◽  
Paul E. Pace ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Rate Constant ◽  
Active Site ◽  
Rate Constants ◽  
Active Sites ◽  
Order Rate Constant ◽  
The Other ◽  
Sulfenic Acid ◽  
Disulfide Formation ◽  
Fixed Concentration

Typical 2-Cys peroxiredoxins (Prxs) react rapidly with H2O2 to form a sulfenic acid, which then condenses with the resolving cysteine of the adjacent Prx in the homodimer or reacts with another H2O2 to become hyperoxidized. Hyperoxidation inactivates the Prx and is implicated in cell signaling. Prxs vary in susceptibility to hyperoxidation. We determined rate constants for disulfide formation and hyperoxidation for human recombinant Prx2 and Prx3 by analyzing the relative proportions of hyperoxidized and dimeric products using mass spectrometry as a function of H2O2 concentration (in the absence of reductive cycling) and in competition with catalase at a fixed concentration of H2O2. This gave a second order rate constant for hyperoxidation of 12,000 m−1 s−1 and a rate constant for disulfide formation of 2 s−1 for Prx2. A similar hyperoxidation rate constant for Prx3 was measured, but its rate of disulfide formation was ∼10-fold higher, making it is more resistant than Prx2 to hyperoxidation. There are two active sites within the homodimer, and at low H2O2 concentrations one site was hyperoxidized and the other present as a disulfide. Prx with two hyperoxidized sites formed progressively at higher H2O2 concentrations. Although the sulfenic acid forms of Prx2 and Prx3 are ∼1000-fold less reactive with H2O2 than their active site thiols, they react several orders of magnitude faster than most reduced thiol proteins. This observation has important implications for understanding the mechanism of peroxide sensing in cells.

REACTIONS OF THERMAL ENERGY IONS: II. RATES OF SOME HYDROGEN TRANSFER ION–MOLECULE REACTIONS

1966 ◽  
Vol 44 (12) ◽  
pp. 1351-1359 ◽  
Author(s):  
A. G. Harrison ◽  
A. Ivko ◽  
T. W. Shannon
Keyword(s):  
Field Strength ◽  
Rate Constant ◽  
Thermal Energy ◽  
Rate Constants ◽  
Hydrogen Transfer ◽  
Thermal Reaction ◽  
Dipole Model ◽  
Protonated Molecule ◽  
Ion Molecule Reactions ◽  
Induced Dipole

The rate constants for the ion–molecule reactions forming the protonated molecule in CH3CN, H2, CH4, and CH3OCH3, the equivalent reactions in the deuteriated species, and the reactions forming COD+ in CO–CD4 mixtures have been measured at thermal energies and at 10.5 V/cm repeller field strength. For H2, HD, D2 and the reactions in CO–CD4 mixtures the rate constant for the thermal reaction is approximately 0.3–0.5 that of the 10.5 V/cm rate constant. For all other cases the ratio of rate constants is approximately unity as predicted by the ion-induced dipole model. The absolute values of the rate constants in most cases are considerably lower than predicted by theory.

Sign in / Sign up

Export Citation Format

Share Document