Hydrolytische Bildung von Perchlorsiloxanen / Formation of Chlorosiloxanes by Hydrolysis

1999 ◽  
Vol 54 (5) ◽  
pp. 577-582 ◽  
Author(s):  
Heike Quellhorst ◽  
Andreas Wilkening ◽  
Nicola Söger ◽  
Michael Binnewies
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Reactive Intermediates ◽  
Reaction Products ◽  
Condensation Reactions ◽  
Intramolecular Condensation ◽  
Hydrolysis Reactions

During the reaction of Si2OCl6 with H2O in the gas phase the intermediate Si2OCl5OH has been observed by mass-spectrometry. Reactive intermediates like this are responsible for the formation of higher chlorosilanes by slow hydrolysis reactions of chlorosilanes and -siloxanes. Reaction products of inter- and intramolecular condensation reactions have been observed by GC-MS-methods.

Laser-induced addition of hydrogen fluoride to unsaturated molecules: the HF + CH2CF2 system

1984 ◽  
Vol 62 (11) ◽  
pp. 2302-2309 ◽  
Author(s):  
Walter H. Beck ◽  
George Burns
Keyword(s):  
Mass Spectrometry ◽  
Information Theory ◽  
Gas Chromatography ◽  
Gas Phase ◽  
Hydrogen Fluoride ◽  
Vibrational Level ◽  
Upper Bound ◽  
Addition Reactions ◽  
Reaction Products ◽  
Addition Rate

Although certain classes of reactions are known to occur via 4-centre transition states, there has been no irrefutable proof that in the gas phase addition reactions also proceed via a 4-centre concerted process. Results of recent information theory calculations on the HF(υ) + CH2CF2 system indicate that it should be possible to observe reaction products for HF(υ = 5). Results are presented here on experiments attempting to achieve laser-induced 4-centre addition of HF to several unsaturated molecules (C2H2, C2H4, C4H6, CH2CF2, and CF2CClF). A mixture of HF and co-reactant was irradiated by a dye-laser tuned photo-acoustically to the fifth vibrational level of HF, and the resulting mixture was analysed by gas chromatography and mass spectrometry. There was no evidence of any laser-induced products. An upper bound was deduced for the HF + CH2CF2 addition rate constant at 610 K: [Formula: see text].

scholarly journals Investigating the composition of organic aerosol resulting from cyclohexene ozonolysis: low molecular weight and heterogeneous reaction products

2006 ◽  
Vol 6 (12) ◽  
pp. 4973-4984 ◽  
Author(s):  
J. F. Hamilton ◽  
A. C. Lewis ◽  
J. C. Reynolds ◽  
L. J. Carpenter ◽  
A. Lubben
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Ion Trap ◽  
High Resolution Mass Spectrometry ◽  
Heterogeneous Reaction ◽  
Organic Aerosol ◽  
Tandem Mass ◽  
Phase Reaction ◽  
Reaction Products ◽  
Aerosol Formation

Abstract. The composition of organic aerosol formed from the gas phase ozonolysis of cyclohexene has been investigated in a smog chamber experiment. Comprehensive gas chromatography with time of flight mass spectrometric detection was used to determine that dicarboxylic acids and corresponding cyclic anhydrides dominated the small gas phase reaction products found in aerosol sampled during the first hour after initial aerosol formation. Structural analysis of larger more polar molecules was performed using liquid chromatography with ion trap tandem mass spectrometry. This indicated that the majority of identified organic mass was in dimer form, built up from combinations of the most abundant small acid molecules, with frequent indication of the inclusion of adipic acid. Trimers and tetramers potentially formed via similar acid combinations were also observed in lower abundances. Tandem mass spectral data indicated dimers with either acid anhydride or ester functionalities as the linkage between monomers. High-resolution mass spectrometry identified the molecular formulae of the most abundant dimer species to be C10H16O6, C11H18O6, C10H14O8 and C11H16O8 and could be used in some cases to reduce uncertainty in exact chemical structure determination by tandem MS.

scholarly journals Investigating the composition of organic aerosol resulting from cyclohexene ozonolysis: low molecular weight and heterogeneous reaction products

2006 ◽  
Vol 6 (4) ◽  
pp. 6369-6399
Author(s):  
J. F. Hamilton ◽  
A. C. Lewis ◽  
J. Reynolds ◽  
L. J. Carpenter ◽  
A. Lubben
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Ion Trap ◽  
High Resolution Mass Spectrometry ◽  
Heterogeneous Reaction ◽  
Organic Aerosol ◽  
Tandem Mass ◽  
Phase Reaction ◽  
Reaction Products ◽  
Aerosol Formation

Abstract. The composition of organic aerosol formed from the gas phase ozonolysis of cyclohexene has been investigated in a smog chamber experiment. Comprehensive gas chromatography with time of flight mass spectrometric detection was used to determine that dicarboxylic acids and corresponding cyclic anhydrides dominated the small gas phase reaction products found in aerosol sampled during the first hour after initial aerosol formation. Structural analysis of larger more polar molecules was performed using liquid chromatography with ion trap tandem mass spectrometry. This indicated that the majority of identified organic mass was in dimer form, built up from combinations of the most abundant small acid molecules, with frequent indication of the inclusion of adipic acid. Trimers and tetramers potentially formed via similar acid combinations were also observed in lower abundances. Tandem mass spectral data indicated dimers with either acid anhydride or ester functionalities as the linkage between monomers. High-resolution mass spectrometry identified the molecular formulae of the most abundant dimer species to be C10H16O6, C11H18O6, C10H14O8 and C11H16O8 and could be used in some cases to reduce uncertainty in exact chemical structure determination by tandem MS.

scholarly journals Gas-Phase Reaction of trans-2-Methyl-2-butenal with Cl: Kinetics, Gaseous Products, and SOA Formation

Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 715
Author(s):  
María Antiñolo ◽  
María Asensio ◽  
José Albaladejo ◽  
Elena Jiménez
Keyword(s):  
Mass Spectrometry ◽  
Gas Phase ◽  
Reaction Pathway ◽  
Aldehyde Group ◽  
Phase Reaction ◽  
Reaction Products ◽  
Gas Phase Reaction ◽  
Gaseous Products ◽  
Flight Mass Spectrometry ◽  
Particle Sizer

The gas-phase reaction between trans-2-methyl-2-butenal and chlorine (Cl) atoms has been studied in a simulation chamber at 298 ± 2 K and 760 ± 5 Torr of air under free-NOx conditions. The rate coefficient of this reaction was determined as k = (2.45 ± 0.32) × 10−10 cm3 molecule−1 s−1 by using a relative method and Fourier transform infrared spectroscopy. In addition to this technique, gas chromatography coupled to mass spectrometry and proton transfer time-of-flight mass spectrometry were used to detect and monitor the time evolution of the gas-phase reaction products. The major primary reaction product from the addition of Cl to the C-3 of trans-2-methyl-2-butenal was 3-chloro-2-butanone, with a molar yield (YProd) of (52.5 ± 7.3)%. Acetaldehyde (Y = (40.8 ± 0.6)%) and HCl were also identified, indicating that the H-abstraction by Cl from the aldehyde group is a reaction pathway as well. Secondary organic aerosol (SOA) formation was investigated by using a fast mobility particle sizer spectrometer. The SOA yield in the Cl + trans-2-methyl-2-butenal reaction is reported to be lower than 2.4%, thus its impact can be considered negligible. The atmospheric importance of the titled reaction is similar to the corresponding OH reaction in areas with high Cl concentration.

scholarly journals Mechanistic insights from mass spectrometry: examination of the elementary steps of catalytic reactions in the gas phase

2015 ◽  
Vol 87 (4) ◽  
pp. 361-377 ◽  
Author(s):  
Krista L. Vikse ◽  
J. Scott McIndoe
Keyword(s):  
Mass Spectrometry ◽  
Real Time ◽  
Gas Phase ◽  
Catalytic Reaction ◽  
Reactive Intermediates ◽  
Mass Spectrometric ◽  
Catalytic Reactions ◽  
Mass Spectrometers ◽  
Elementary Steps ◽  
Reaction Vessels

AbstractReal-time mass spectrometric monitoring of speciation in a catalytic reaction while it is occurring provides powerful insights into mechanistic aspects of the reaction, but cannot be expected to elucidate all details. However, mass spectrometers are not limited just to analysis: they can serve as reaction vessels in their own right, and given their powers of separation and activation in the gas phase, they are also capable of generating and isolating reactive intermediates. We can use these capabilities to help fill in our overall understanding of the catalytic cycle by examining the elementary steps that make it up. This article provides examples of how these simple reactions have been examined in the gas phase.

COMPUTER MODELING OF CHEMICAL EQUILIBRIUMS IN WO3–H2O SYSTEM

2017 ◽  
pp. 35-48 ◽  
Author(s):  
V.P. Bondarenko ◽  
O.O. Matviichuk
Keyword(s):  
Transition Temperature ◽  
Gas Phase ◽  
Single Phase ◽  
Reference Data ◽  
Maximum Amount ◽  
Reaction Products ◽  
Influence Of Temperature ◽  
Equilibrium Chemical ◽  
Program Data ◽  
Good Agreement

Detail investigation of equilibrium chemical reactions in WO3–H2O system using computer program FacktSage with the aim to establish influence of temperature and quantity of water on formation of compounds of H2WO4 and WO2(OH)2 as well as concomitant them compounds, evaporation products, decomposition and dissociation, that are contained in the program data base were carried out. Calculations in the temperature range from 100 to 3000 °С were carried out. The amount moles of water added to 1 mole of WO3 was varied from 0 to 27. It is found that the obtained data by the melting and evaporation temperatures of single-phase WO3 are in good agreement with the reference data and provide additionally detailed information on the composition of the gas phase. It was shown that under heating of 1 mole single-phase WO3 up to 3000 °С the predominant oxide that exist in gaseous phase is (WO3)2. Reactions of it formation from other oxides ((WO3)3 and (WO3)4) were proposed. It was established that compound H2WO4 is stable and it is decomposed on WO3 and H2O under 121 °C. Tungsten Oxide Hydrate WO2(OH)2 first appears under 400 °С and exists up to 3000 °С. Increasing quantity of Н2О in system leads to decreasing transition temperature of WO3 into both liquid and gaseous phases. It was established that adding to 1 mole WO3 26 mole H2O maximum amount (0,9044–0,9171 mole) WO2(OH)2 under temperatures 1400–1600 °С can be obtained, wherein the melting stage of WO3 is omitted. Obtained data also allowed to state that that from 121 till 400 °С WO3–Н2O the section in the О–W–H ternary system is partially quasi-binary because under these temperatures in the system only WO3 and Н2O are present. Under higher temperatures WO3–Н2O section becomes not quasi-binary since in the reaction products WO3 with Н2O except WO3 and Н2O, there are significant amounts of WO2(OH)2, (WO3)2, (WO3)3, (WO3)4 and a small amount of atoms and other compounds. Bibl. 12, Fig. 6, Tab. 5.

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