Mass spectrometric studies of chemical reactions in shock waves. Part II. The thermal decomposition of diazomethane

1970 ◽  
Vol 48 (23) ◽  
pp. 3623-3634 ◽  
Author(s):  
J. E. Dove ◽  
J. Riddick
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Shock Waves ◽  
Vibrational Energy ◽  
Mass Spectrometric ◽  
Unimolecular Decomposition ◽  
Vibrationally Excited ◽  
Flight Mass Spectrometry ◽  
Concentration Changes ◽  
Products Of Reaction

The thermal decomposition of CH2N2, highly diluted in Kr, has been studied in shock waves by using time-of-flight mass spectrometry to follow concentration changes in the reacting gas. Observations were made at pressures 45 to 95 Torr and temperatures 820 to 1200°K. The principal products of reaction are C2H4, C2H2, and N2. The primary step appears to be a second order unimolecular decomposition of CH2N2 into CH2 and N2; for this step, log k = (9.61 ± 0.21) − (15 800 ± 1 000)/2.303RT(cal mole−1 and cm3 mole s units.) Some decomposition of CH2N2 into HCN and NH is also indicated. The formation of C2H2 is believed to occur through vibrationally excited C2H4, formed by reaction between CH2 and CH2N2. Calculations using the R.R.K.M. theory indicate that 50 + 10% of the energy of this reaction appears as vibrational energy of the product C2H4.

Mass spectrometric studies of chemical reactions in shock waves: the thermal decomposition of nitrous oxide

1969 ◽  
Vol 47 (4) ◽  
pp. 521-538 ◽  
Author(s):  
S. C. Barton ◽  
J. E. Dove
Keyword(s):  
Thermal Decomposition ◽  
Shock Waves ◽  
Rate Coefficient ◽  
Mass Spectrometric Study ◽  
Mass Spectrometric ◽  
Unimolecular Decomposition ◽  
Reflected Shock ◽  
Secondary Reactions ◽  
Gas Reactions ◽  
Collision Mechanism

Apparatus for the mass spectrometric study of rapid gas reactions in reflected shock waves is described. This apparatus has been applied to the thermal decomposition of 2% N2O in Kr at total gas concentrations of about 1.6 × 10−6 mole cm−3, in the temperature range 1800 to 2800 °K. The principal products of the reaction were found to be N2, O2, NO, and O. The rate coefficient for the unimolecular decomposition of N2O was calculated from the experimental data, and the rates of the secondary reactions between O and N2O were estimated. The possibility of the occurrence of a "weak collision" mechanism in the unimolecular reaction of N2O is discussed.

scholarly journals Thermal decomposition of cyclohexane by flash pyrolysis vacuum ultraviolet photoionization time-of-flight mass spectrometry: a study on the initial unimolecular decomposition mechanism

2021 ◽  
Vol 23 (16) ◽  
pp. 9804-9813
Author(s):  
Kuanliang Shao ◽  
Xinghua Liu ◽  
Paul J. Jones ◽  
Ge Sun ◽  
Mariah Gomez ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Vacuum Ultraviolet ◽  
Time Of Flight ◽  
Decomposition Mechanism ◽  
Bond Rupture ◽  
Unimolecular Decomposition ◽  
Flash Pyrolysis ◽  
Flight Mass Spectrometry

Cyclohexane decomposes mainly via C–C bond rupture producing 1,6-hexyl diradical. The diradical leads to 1-hexene and can also directly dissociate. C6H12 does not decompose to ˙C6H11 + H. Benzene can be formed via sequential H2 eliminations of C6H12.

Identification of Phosphorylcholine-Substituted Peptides by Their Characteristic Mass Spectrometric Fragmentation

2005 ◽  
Vol 11 (3) ◽  
pp. 335-344 ◽  
Author(s):  
Julia Grabitzki ◽  
Volker Sauerland ◽  
Rudolf Geyer ◽  
Günter Lochnit
Keyword(s):  
Mass Spectrometry ◽  
Ion Trap ◽  
Neutral Loss ◽  
Structural Data ◽  
Mass Spectrometric ◽  
Peptide Backbone ◽  
Fragmentation Behavior ◽  
Flight Mass Spectrometry ◽  
Characteristic Fragmentation ◽  
Fragmentation Patterns

Phosphorylcholine (PC)-substituted biomolecules are wide-spread, highly relevant antigens of parasites, since this small hapten has been found to be a potent immunomodulatory component which allows the establishment of long lasting infections of the host. Structural data, especially of protein bound PC-substituents, are still rare due to the observation that mass spectrometric analyses are mostly hampered by this zwitterionic substituent resulting in low sensitivities and unusual but characteristic fragmentation patterns. Here, we investigated the fragmentation behavior of synthetic PC-substituted peptides by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and electrospray ionization ion-trap mass spectrometry. We could show that the predominant neutral loss of a trimethylamine unit (Hoffmann elimination) leads to cyclic phosphate derivatives which prevent further fragmentation of the peptide backbone by stabilizing the positive charge at this particular side chain. Knowledge of this PC-specific fragmentation might help to identify PC-substituted biomolecules and facilitate their structural analysis.

scholarly journals Software Solutions for Indication and Identification of Pathogenic Microoranisms Using Time-of-Flight Mass Spectrometry

2021 ◽  
pp. 40-50
Author(s):  
D. V. Ul’shina ◽  
D. A. Kovalev ◽  
I. V. Kuznetsova ◽  
O. V. Bobrysheva ◽  
T. L. Krasovskaya ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Programming Language ◽  
Time Of Flight ◽  
Mass Spectrometric ◽  
Mass Spectrometry Data ◽  
Spectrometric Analysis ◽  
Spectrometric Data ◽  
Maldi Tof Mass Spectrometry ◽  
Maldi Tof ◽  
Flight Mass Spectrometry

The effectiveness of differentiation of bacterial pathogens using MALDI-TOF mass spectrometry depends on the quality of sample preparation, compliance with mass spectrometric analysis parameters and statistical approaches used, implemented by various modern software tools. The review provides a brief description of the most known software used in the processing and bioinformation analysis of time-of-flight mass spectrometry data. A list of computer platforms, programs and environments, both commercial and publicly available, is presented. The results of indication and identification of pathogens of particularly dangerous and natural-focal infections by MALDI-TOF mass spectrometry using publicly available software – programming language R, Mass-Up, MicrobeMS, licensed – MatLab, ClinProTools, as well as free web applications, including, Speclust, Ribopeaksare provided. The data on usage of such well-known platforms as MALDI BioTyper, SARAMIS Vitek-MS and Andromas (Andromas SAS, France) for inter- and intra-specific differentiation of closely related species are presented. Results of identification and differentiation of microorganisms applying MALDI-TOF mass spectrometry based on detection of specific proteins for cross-comparison – biomarkers – are given. The analysis shows that the programming language R environment is one of the publicly available universal platforms with an optimal combination of algorithms for processing and interpreting of a large array of mass spectrometric data.

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