HYDROGEN ATOM RECOMBINATION IN THE FLOW SYSTEM ATTACHED TO A MASS SPECTROMETER AND USED FOR THE STUDY OF MERCURY-SENSITIZED REACTIONS

1962 ◽  
Vol 40 (12) ◽  
pp. 2409-2411 ◽  
Author(s):  
P. Kebarle ◽  
M. Avrahami
Keyword(s):  
Hydrogen Atom ◽  
Mass Spectrometer ◽  
Flow System

not available

The reaction of active nitrogen with fluoroethylenes

1982 ◽  
Vol 60 (20) ◽  
pp. 2629-2633 ◽  
Author(s):  
William E. Jones ◽  
Mahmooda G. Ahmed
Keyword(s):  
Mass Spectrometer ◽  
Reaction Mechanisms ◽  
Flow System ◽  
Intermediate Species ◽  
Active Nitrogen ◽  
Reacting Mixtures

The reactions of active nitrogen with the fluoroethylenes C2H3F, 1,1-C2H2F2, C2HF3, and C2F4 have been investigated in a conventional flow system using a mass spectrometer to detect products and intermediate species. Addition of various gases (H, H2, NH3, CH4, N2O, [Formula: see text], and F) to the reacting mixtures provides evidence that both Hand F atoms play significant roles in the reaction mechanisms, while [Formula: see text] does not. A brief discussion of possible mechanisms is presented.

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.

Mass spectrometric study of the reaction of nitrogen atoms with acetaldehyde

1968 ◽  
Vol 302 (1469) ◽  
pp. 167-183 ◽  
Keyword(s):  
Reaction Mechanism ◽  
Mass Spectrometer ◽  
Rate Constant ◽  
Electric Discharge ◽  
Flow System ◽  
Hydrogen Abstraction ◽  
Mass Spectrometric Study ◽  
Mass Spectrometric ◽  
Spectrometric Study ◽  
System A

The reaction of nitrogen atoms, produced by an electric discharge, with acetaldehyde has been studied in a flow system, a mass spectrometer being used to follow the course of the reaction. Sampling was carried out through a small hole in a gold diaphragm. The main stable products were HCN, H 2 and CO; a small amount of glyoxal was also formed. In addition appreciable amounts of a substance yielding ions of m/e = 43 were obtained. Arguments are presented for identifying this with the radical CH 2 CHO. Small amounts of a product giving ions of m/e = 86 were also produced. The nature of this material is discussed. No evidence was obtained for any hydrogen abstraction by nitrogen atoms. Experiments were also carried out with CH 3 CDO to clarify certain aspects of the proposed reaction mechanism . A few experimental results obtained with propionaldehyde can be understood in similar terms. The rate constant of the reaction N + CH 3 CHO → HCN + H 2 + HCO was deduced to be 1.20 ± 0.15 x 10 10 mole -1 cm 3 s -1 at 296°K.

Diffusive and convective flow in a hydrogen-atom flow system

1968 ◽  
Vol 46 (24) ◽  
pp. 3899-3902 ◽  
Author(s):  
Philip B. Rudnick ◽  
Sidney Toby
Keyword(s):  
Hydrogen Atom ◽  
Surface Area ◽  
Flow Rate ◽  
Convective Flow ◽  
Total Pressure ◽  
Flow System ◽  
Linear Flow ◽  
Flow Signal ◽  
Concentration Time ◽  
Diffusive Flow

Diffusive and convective flow was studied in a hydrogen-atom flow system using an isothermal calorimetric detector. By varying detector area, total pressure, and linear flow rate, the importance of axial diffusion in the system was investigated. Under conditions of predominantly diffusive flow, signal–distance plots were independent of flow rate. When convective flow predominated, concentration–time plots were independent of flow rate. The efficiency of a detector was clearly dependent on its surface area within wide limits, but diffusion gradients produced by the presence of even large detectors did not appear to be important.

THE REACTIONS OF ACTIVE NITROGEN WITH ETHYLENE AND DEUTERATED ETHYLENES

1966 ◽  
Vol 44 (22) ◽  
pp. 2691-2701 ◽  
Author(s):  
Kenneth D. Foster ◽  
P. Kebarle ◽  
H. B. Dunford
Keyword(s):  
Hydrogen Atom ◽  
Mass Spectrometer ◽  
Rate Constant ◽  
Reaction Times ◽  
Order Rate Constant ◽  
Second Order ◽  
Atomic Nitrogen ◽  
Large Excess ◽  
Active Nitrogen ◽  
Initial Concentration

The reaction of active nitrogen with ethylene and deuterated ethylenes has been investigated by use of a mass spectrometer. The rate of disappearance of atomic nitrogen in the presence of ethylene appears to obey the equation[Formula: see text]where kapp is an apparent second order rate constant and [ethylene]0 is the initial concentration of added ethylene. However, exceptions to this equation are found at 0.6 Torr either for short reaction times or for small concentrations of added ethylene, and apparently for short reaction times at 2.6 Torr when a large excess of ethylene is added. Where the above equation is obeyed, kapp = (3 ± 1) × 10−13 cc molecule−1 s−1. The formation of C2D4 in the reaction of active nitrogen with C2D3H is interpreted as further evidence for the importance of hydrogen atom reactions in intermediate steps of the reaction of active nitrogen with ethylene.

MASS SPECTROMETRIC STUDY OF THE REACTIONS OF SOME HYDROCARBONS WITH ACTIVE NITROGEN

1959 ◽  
Vol 37 (3) ◽  
pp. 579-582 ◽  
Author(s):  
John T. Herron ◽  
J. L. Franklin ◽  
Paul Bradt
Keyword(s):  
Mass Spectrometer ◽  
Mass Spectra ◽  
Flow System ◽  
Mass Spectrometric Study ◽  
Mass Spectrometric ◽  
Spectrometric Study ◽  
Active Nitrogen ◽  
Cyano Radical

The reactions of active nitrogen with acetylene, ethylene, and propylene have been studied in a flow system using a mass spectrometer to analyze the products continuously. Certain features of the mass spectra of the products can be explained on the basis of cyano radical replacement reactions.

The peroxides formed during hydrocarbon slow combustion and their role in the mechanism

1961 ◽  
Vol 261 (1306) ◽  
pp. 388-401 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Hydrogen Atom ◽  
Flow System ◽  
Reaction Vessel ◽  
The Other ◽  
Dicarbonyl Compound ◽  
Hydroperoxide Decomposition ◽  
Peroxide Decomposition ◽  
Slow Combustion ◽  
Free Aldehyde

The peroxides formed during the slow combustion of five hydrocarbons in a flow system have been identified and the approximate yields estimated. With propane at 327°C and 2, 2, 3-trimethylbutane at 365 to 385°C the products contained only traces of hydrogen peroxide, its addition compounds with aldehyde and (with C 3 H 8 ) peracetic acid. With n -butane between 310 and 345°C and cylohexane between 290 and 316°C appreciable yields of peroxide were obtained (~ 10 to 20% of the hydrocarbon oxidized). These consisted of the monohydroperoxides, hydrogen peroxide and their addition compounds with aldehydes. With n -C 4 H 10 the relative amount of H 2 O 2 free and combined ( ~ 50% of the total peroxide yield) was much higher than with C 6 H 12 and some perpropionic acid was also detected. With n -heptane between 240 and 310°C the yield of peroxide in the products was also con­ siderable ( ~ 20% of the hydrocarbon reacted), and consisted mainly of dihydroperoxyheptane and its addition compounds with aldehydes (mainly formaldehyde), with much smaller amounts of monohydroperoxide and hydrogen peroxide (free and combined with aldehyde), diheptylperoxide and possible trihydroperoxyheptane. Packing the vessel increased the relative amount of aldehyde-addition compounds but did not affect the yield of free aldehyde, which apparently depended only on the temperature, being zero at 240°C. All aldehydes up to C 5 H 11 CHO were formed at higher temperatures, but those from C 3 to C 6 only in small yield. A little β -dicarbonyl compound and carboxylic acids were also detected in the products. The modes of formation and decomposition of the peroxides is discussed. It is suggested the dihydroperoxyheptane resulted from the abstraction of a hydrogen atom internally in the C 7 H 15 O 2 radical from the CH 2 group β or γ to the point of original attack, that aldehydes were produced partly by heterogeneous hydroperoxide decomposition and partly by decomposition of RO 2 radicals, and that with n -heptane the aldehyde-hydroperoxide compounds were formed mainly on the walls of the reaction vessel. Chain branching in the oxidation of propane and 2, 2, 3-trimethylbutane was presumably due exclusively to the oxidation of aldehydes formed, whereas with the other three hydrocarbons branching due to homo­geneous peroxide decomposition was probably important up to about 350°C.

Photochemical Studies by Means of a Field Ion Mass Spectrometer

1966 ◽  
Vol 21 (1-2) ◽  
pp. 135-140 ◽  
Author(s):  
H. Okabe ◽  
H. D. Beckey ◽  
W. Groth
Keyword(s):  
Mass Spectrometer ◽  
Mass Spectra ◽  
Flow System ◽  
Low Pressure ◽  
Ion Source ◽  
Mass Spectrometric ◽  
Gas Pressure ◽  
Spectrometric Investigation ◽  
Mercury Lamp ◽  
Mass Spectrometric Investigation

A mass spectrometric investigation was carried out on the direct photolyses of propene, 1-butene, and hydrazine at 1849 A with a field ion source in a flow system. Comparisons were made with Pt tip and wire emitters. It was found that, without illumination, mass spectra obtained with the wire were accompanied by a number of fragment peaks amounting to almost 1%. Since these peaks interfere with those produced photochemically, the tip emitter was used mostly for the photochemical studies although it gave 100 times less current and was less stable. The photochemical products formed at a gas pressure of 10 μ by a low pressure mercury lamp were detected after approximately 10 m sec. The three main peaks observed in the propene photolysis were at masses 27, 28, and 56, indicating the processes:C3H6+hv→C2H3+CH3, C3H6+hv→C2H4+CH2, CH2+C3H6→C4H8.The photolysis of 1-butene gave four main peaks at masses 40, 41, 42, and 70, suggesting steps, C4H8+hv→C3H4+ (H+CH3) or CH4, C4H8+hv→C3H5+CH3, C4H8+hv→C3H6+CH2, CH2+C4H8C5H10.The only peak found with the photolysis of hydrazine was at mass 17, indicating the step, N2H4+hv→NH3+NH.The possibility of forming these products by secondary processes is discussed.

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