FREE RADICALS BY MASS SPECTROMETRY: XXXII. THERMAL DECOMPOSITION OF CYCLOPENTYL RADICALS

1965 ◽  
Vol 43 (3) ◽  
pp. 565-569 ◽  
Author(s):  
T. F. Palmer ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Free Radicals ◽  
Elevated Temperatures ◽  
Bond Rupture ◽  
Low Pressures

At low pressures and elevated temperatures cyclopentyl radicals are found to dissociate mainly by two modes of reaction: about 34% by loss of H atom to form cyclopentene, and about 66% by a C—C bond rupture to form ethylene and allyl radicals. Under the conditions employed no evidence for a third possible mode, the loss of H2 to form cyclopentenyl radical, could be found. It is estimated that an incidence of 2% of the latter could have been detected.

FREE RADICALS BY MASS SPECTROMETRY: XXII. PRIMARY DECOMPOSITION STEPS IN THE MERCURY-PHOTOSENSITIZED DECOMPOSITION OF METHANOL AND DIMETHYL ETHER

1961 ◽  
Vol 39 (1) ◽  
pp. 102-109 ◽  
Author(s):  
R. F. Pottie ◽  
A. G. Harrison, ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Free Radicals ◽  
Dimethyl Ether ◽  
Excited Molecule ◽  
Primary Decomposition ◽  
Oh Radicals ◽  
No Formation ◽  
Abstraction Reaction ◽  
Reaction Proceeds ◽  
Low Pressures

The Hg 3P1 photosensitized decomposition of methanol at low pressures proceeds mainly by a dissociation into CH3O radicals and H atoms. No formation of CH2OH radicals is observed. A subsidiary reaction to form CH3 and OH may also be a primary step. Formation of CH2OH radicals at higher pressures is attributed to an abstraction reaction of CH3O with CH3OH.Two primary modes of dissociation are found to occur for dimethyl ether:[Formula: see text]The relative probabilities of occurrence at low pressures are ∼45% and ∼50%, respectively. The possibility that the second reaction proceeds by formation of an excited molecule is discussed.

FREE RADICALS BY MASS SPECTROMETRY: VII. THE IONIZATION POTENTIALS OF ETHYL, ISOPROPYL, AND PROPARGYL RADICALS AND THE APPEARANCE POTENTIALS OF THE RADICAL IONS IN SOME DERIVATIVES

1955 ◽  
Vol 33 (5) ◽  
pp. 861-869 ◽  
Author(s):  
J. B. Farmer ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Free Radicals ◽  
Kinetic Energy ◽  
Electron Impact ◽  
Ionization Potentials ◽  
Bond Dissociation Energies ◽  
Radical Ions ◽  
Dissociation Energies ◽  
Propargyl Radicals

The ionization potentials of ethyl, isopropyl, and propargyl radicals have been measured by electron impact on radicals produced by thermal decomposition of appropriate compounds. The values are:ethyl 8.78±0.05 ev., isopropyl 7.90±0.05 ev., and propargyl 8.25±0.08 ev. From the appearance potentials of these ions in various compounds, the following values of bond dissociation energies were obtained:[Formula: see text][Formula: see text] assuming no kinetic energy of the products.

Study of the thermal decomposition of nitropyrroles at low pressures using field mass spectrometry

1977 ◽  
Vol 26 (2) ◽  
pp. 404-407
Author(s):  
G. P. Sharnin ◽  
V. V. Nurgatin ◽  
R. A. Khabirov ◽  
V. D. Kolosov ◽  
L. I. Khmel'nitskii ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Field Mass ◽  
Low Pressures

FREE RADICALS BY MASS SPECTROMETRY: III. RADICALS IN THE THERMAL DECOMPOSITION OF SOME BENZENE DERIVATIVES

1953 ◽  
Vol 31 (1) ◽  
pp. 30-41 ◽  
Author(s):  
K. U. Ingold ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Free Radicals ◽  
Free Radical ◽  
Mass Spectrometer ◽  
Phenyl Ether ◽  
Benzyl Ether ◽  
Benzene Derivatives ◽  
Atomic Carbon ◽  
Benzene Toluene

The following benzene derivatives have been pyrolyzed in a free radical mass spectrometer: benzene, toluene, benzaldehyde, anisole, diphenyl, phenyl ether, and benzyl ether. The products and intermediates were analyzed, particular attention being paid to the formation (and stability) of any aromatic free radicals found. The phenyl, benzyl, phenoxy, and benzoyl radicals, as well as atomic carbon, were detected. The first two could be obtained abundantly and are fairly stable below 1150°. The oxygenated radicals were much less abundant and appeared to be less stable.

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.

scholarly journals FREE RADICALS BY MASS SPECTROMETRY: XXXIV. A FLOW REACTOR FOR MEASUREMENT OF FAST THERMAL REACTIONS

1966 ◽  
Vol 44 (18) ◽  
pp. 2205-2210 ◽  
Author(s):  
I. P. Fisher ◽  
J. B. Homer ◽  
B. Roberts ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Thermal Decomposition ◽  
Free Radicals ◽  
Rate Constants ◽  
Flow Reactor ◽  
Residence Times ◽  
Thermal Reactions ◽  
New Type ◽  
Good Agreement ◽  
Gas Pressures

A new type of flow reactor for use with a mass spectrometer has been constructed, in which many of the disadvantages of flow systems for rate measurements have been overcome. Rate constants for unimolecular decompositions can be measured in the range 50 – 5 000 s−1, with helium carrier gas pressures of 10–50 mm and residence times of 10−3 to 10−1 s. Measurements of the rate of thermal decomposition of trioxane are in good agreement with the rates predicted from literature data obtained at much lower temperatures.

scholarly journals Free radicals by mass spectrometry. XXXIX. Primary steps in the mercury-photosensitized decompositions of methyl and ethyl mercaptan

1968 ◽  
Vol 46 (18) ◽  
pp. 2925-2927 ◽  
Author(s):  
S. Yamashita ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Free Radicals ◽  
Bond Rupture ◽  
Methyl Mercaptan ◽  
Ethyl Mercaptan ◽  
A Minor

The reaction between Hg(3P1) atoms and methyl mercaptan at 55° is mainly H-atom removal from sulfur[Formula: see text]with a minor participation (~10%) of C—S bond rupture[Formula: see text]Ethyl mercaptan dissociates by two main processes[Formula: see text]Some evidence was found for a small amount of dissociation by C—C bond rupture. No C—H bond rupture in either compound could be detected.

Effects of phenolic compounds from blueberry leaves on the thermal decomposition of trimethylamine oxide in squid extract

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Yingchang Li ◽  
Fengxia Du ◽  
Suzhen Song ◽  
Shuangyan Li ◽  
Xianqing Yang ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Free Radicals ◽  
Chlorogenic Acid ◽  
Theoretical Basis ◽  
Leaf Extract ◽  
Aquatic Products ◽  
Trimethylamine Oxide ◽  
Mechanism Of Inhibition ◽  
Development And Utilization ◽  
Blueberry Leaves

AbstractThe effects of chlorogenic acid and quercetin-3-D-galactoside on the decomposition of trimethylamine oxide (TMAO) in squid extract and the main mechanism of inhibition of thermal decomposition were studied. The results indicated that chlorogenic acid and quercetin-3-D-galactoside could inhibit decomposition of TMAO in squid extract. The amount of TMAO was increased by 11.79 and 15.76% in squid extract treated with chlorogenic acid and quercetin-3-D-galactoside from 0 and 2.5 g/L, respectively. The contents of trimethylamine (TMA), dimethylamine (DMA), and formaldehyde (FA) were significantly decreased with increasing contents of chlorogenic acid and quercetin-3-D-galactoside. There were many free radicals in squid extract at high temperatures; however, the free radical signals were weakened after the addition of chlorogenic acid and quercetin-3-D-galactoside therein. This implied that chlorogenic acid and quercetin-3-D-galactoside could inhibit the thermal decomposition of TMAO in squid extract, which was associated with the scavenging of their free radicals. This result provides a theoretical basis for the development and utilization of blueberry leaf extract as an efficient FA inhibitor for aquatic products.

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