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 Identification of Aroma Differences in Refined and Whole Grain Extruded Maize Puffs

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2261 ◽  
Author(s):  
Kenneth Smith ◽  
Devin G. Peterson
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Quantitative Analysis ◽  
Descriptive Analysis ◽  
Analytical Data ◽  
Gas Chromatography Mass Spectrometry ◽  
Maillard Reaction Products ◽  
Reaction Products ◽  
Whole Grain ◽  
Whole Grain Flour

Differences in the aroma profiles of extruded maize puffs made from refined grain and whole grain flour were investigated. Gas chromatography/mass spectrometry/olfactometry (GC/MS/O) analysis reported 13 aroma compounds with a flavor dilution (FD) value ≥16. Quantitative analysis identified eight compounds as statistically different, of which seven compounds were higher in concentration in the whole grain sample. Sensory recombination and descriptive analysis further supported the analytical data, with higher mean aroma intensities for cooked, corn chip, roasted, and toasted attributes for the whole grain sample. Generally, the compounds responsible for perceived differences in whole grain maize extruded puffs were associated with increased levels of Maillard reaction products, such as 2-ethyl-3,5-dimethylpyrazine and 2-acetyl-2-thiazoline.

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.

Oxidation of triamantane by sulphuric acid

1983 ◽  
Vol 48 (4) ◽  
pp. 1074-1076 ◽  
Author(s):  
Zdeněk Kafka ◽  
Luděk Vodička ◽  
Milan Hájek
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Sulphuric Acid ◽  
Functional Groups ◽  
Reaction Products ◽  
Reaction Conditions ◽  
Nmr Spectrometry ◽  
C Nmr

The oxidation of triamantane by sulphuric acid was studied in various reaction conditions. 8-Triamantanone, 8,16-triamantanedione, and 15-hydroxy-8-triamantanone were isolated and identified as reaction products. The reaction was monitored and the purity of the compounds prepared was checked by gas chromatography and mass spectrometry, the position of the functional groups was determined by 13C NMR spectrometry.

Metabolic Profiles: Gas-Phase Methods for Analysis of Metabolites

1971 ◽  
Vol 17 (8) ◽  
pp. 802-809 ◽  
Author(s):  
E C Horning ◽  
M G Horning
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Drug Metabolism ◽  
Gas Phase ◽  
Metabolic Pathways ◽  
Analytical Techniques ◽  
Gas Chromatography Mass Spectrometry ◽  
Metabolic Profiles ◽  
Developmental Studies ◽  
Drug Metabolites

Abstract Multicomponent analyses were carried out for three types of urinary constituents: steroids, acids, and drugs and drug metabolites. The methods were based on gas-phase analytical techniques, which include the use of instruments and instrumental systems for gas chromatography, gas chromatography—mass spectrometry, and mass spectrometry—computerization. After isolating an analytical sample, we prepared derivatives in each instance. Gas chromatography was used for separations, mass spectrometry for identification. These procedures for obtaining metabolic profiles may be used in various ways, including studies of abnormal conditions, drug metabolism, and the effects of drugs on metabolic pathways, as well as for human developmental studies.

scholarly journals Simultaneous Determination of Four Aldehydes in Gas Phase of Mainstream Smoke by Headspace Gas Chromatography-Mass Spectrometry

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Xiaotao Zhang ◽  
Ruoning Wang ◽  
Li Zhang ◽  
Jianke Wei ◽  
Yibin Ruan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Gas Phase ◽  
Gas Chromatography Mass Spectrometry ◽  
Headspace Gas Chromatography ◽  
Mainstream Smoke ◽  
Chromatography Mass Spectrometry ◽  
Headspace Gas ◽  
Cigarette Mainstream Smoke

A method for simultaneous determination of acetaldehyde, propionaldehyde, acrolein, and crotonaldehyde in gas phase of cigarette mainstream smoke by headspace gas chromatography-mass spectrometry was developed and validated. Gas phase components of mainstream cigarette smoke were extracted with methanol, and then the samples were separated on a DB 624 (60 m, 0.32 mm x 1.8 mm) column, analyzed with headspace gas chromatography-mass spectrometry, and quantified by isotope internal standard. The linearities of acetaldehyde, propionaldehyde, acrolein, and crotonaldehyde were good (R2>0.992). The recoveries of acetaldehyde, propionaldehyde, acrolein, and crotonaldehyde were between 78.5% and 115%. The relative standard deviations were less than 10%. The limits of detection and limits of quantitation were 0.014 μg/cigarette ~0.12 μg/cigarette and 0.045 μg/cigarette ~0.38 μg/cigarette, respectively. The method had advantage of high sensitivity, it did not require derivatization of 2,4-dinitrophenylhydrazine and avoided a large number of adverse reactions during the process of derivation to improve the accuracy of result, and it was suitable for quantitative analysis of four aldehydes in gas phase of cigarette mainstream smoke.

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