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.

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.

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: XI. THE MERCURY PHOTOSENSITIZED DECOMPOSITION OF C2–C4 OLEFINS

1956 ◽  
Vol 34 (6) ◽  
pp. 701-715 ◽  
Author(s):  
F. P. Lossing ◽  
D. G. H. Marsden ◽  
J. B. Farmer
Keyword(s):  
Mass Spectrometry ◽  
Free Radicals ◽  
Hydrogen Atom ◽  
Mass Spectrometer ◽  
Cross Sections ◽  
Methyl Radicals ◽  
Allyl Radical

The mercury photosensitized (Hg3P1) decomposition of olefins has been examined using a reactor coupled directly to a mass spectrometer. The primary split of ethylene has been shown to be predominantly molecular, and that of propylene mainly into an allyl radical and a hydrogen atom. With 1-butene the split is predominantly at a C–C bond giving allyl and methyl radicals, although a rupture of a C–H bond occurs as well. With 2-butene and isobutene a C–H bond is broken. It is concluded that the allyl and methallyl radicals produced have large cross sections for reaction with excited mercury atoms.

Free radicals by mass spectrometry. XL. Primary processes and transient intermediates in the mercury (3P1) photosensitization of hydrazine

1969 ◽  
Vol 47 (8) ◽  
pp. 1391-1393 ◽  
Author(s):  
A. Jones ◽  
F. P. Lossing
Keyword(s):  
Mass Spectrometry ◽  
Free Radicals ◽  
Mass Spectrometer ◽  
Direct Evidence ◽  
Flow Reactor ◽  
Low Pressure ◽  
Primary Decomposition ◽  
Fast Flow ◽  
Transient Intermediates ◽  
Fast Flow Reactor

The low pressure mercury (3P1) photosensitized decomposition of hydrazine has been studied at 55 °C in a fast flow reactor coupled to a mass spectrometer. Direct evidence was obtained for the participation of N2H2, N2H3, NH2, and NH in the decomposition, and two primary decomposition modes were established[Formula: see text]

Thermal decomposition ractions of caledonite and their products

1986 ◽  
Vol 50 (357) ◽  
pp. 521-526 ◽  
Author(s):  
D. J. Morgan ◽  
S. St. J. Warne ◽  
S. B. Warrington ◽  
P. H. A. Nancarrow
Keyword(s):  
Mass Spectrometry ◽  
Phase Transition ◽  
Thermal Analysis ◽  
Thermal Decomposition ◽  
Differential Thermal Analysis ◽  
Mass Spectrometer ◽  
Mass Spectra ◽  
Decomposition Products ◽  
Lead Sulphate ◽  
Ion Fragmentation

AbstractThe thermal decomposition of caledonite has been examined by simultaneous differential thermal analysis, thermogravimetry and mass spectrometry. Structural H2O and CO2 are liberated endothermically between 300 and 400°C leaving a residue of lead sulphate, oxysulphate, and Cu(I) and Cu(II) oxides. A series of sharp endothermic peaks between 850 and 950°C correspond to phase transition and melting reactions of the PbO-PbSO4 mixture. The sulphate anion breaks down above 880 °C. Mass spectra of the gaseous decomposition products show SO2, SO, and O2, although SO is an artefact arising from ion fragmentation of the SO2 within the mass spectrometer. The residue at 1060 °C is composed predominantly of 2PbO · PbSO4 and Cu(I) and Cu(II) oxides.

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.

Study of antioxidant potential in leaves, stems, nuts of Juglans regia L.

2012 ◽  
Vol 1 (10) ◽  
pp. 79 ◽  
Author(s):  
G. Raja* ◽  
Ivvala Anand Shaker ◽  
Inampudi Sailaja ◽  
R. Swaminathan ◽  
S. Saleem Basha ◽  
...  
Keyword(s):  
Free Radicals ◽  
Free Radical ◽  
Antioxidant Activities ◽  
Radical Scavenging Activity ◽  
Juglans Regia ◽  
Radical Scavenging ◽  
Antioxidant Compounds ◽  
Free Radical Damage ◽  
Radical Damage

Natural antioxidants can protect the human body from free radicals and retard the progress of many chronic diseases as well as lipid oxidative rancidity in foods. The role of antioxidants has protected effect against free radical damage that may cause many diseases including cancer. Primary sources of naturally occurring antioxidants are known as whole grains, fruits, and vegetables. Several studies suggest that regular consumption of nuts, mostly walnuts, may have beneficial effects against oxidative stress mediated diseases such as cardiovascular disease and cancer. The role of antioxidants has attracted much interest with respect to their protective effect against free radical damage that may cause many diseases including cancer. Juglans regia L. (walnut) contains antioxidant compounds, which are thought to contribute to their biological properties. Polyphenols, flavonoids and flavonols concentrations and antioxidant activity of Leaves, Stems and Nuts extract of Juglans regia L. as evaluated using DPPH, ABTS, Nitric acid, hydroxyl and superoxide radical scavenging activity, lipid peroxidation and total oxidation activity were determined. The antioxidant activities of Leaves, Stems and Nuts extract of Juglans regia L. were concentration dependent in different experimental models and it was observed that free radicals were scavenged by the test compounds in all the models.

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