THE PHOTO-OXIDATION OF AZOMETHANE

1955 ◽  
Vol 33 (3) ◽  
pp. 496-506 ◽  
Author(s):  
G. R. Hoey ◽  
K. O. Kutschke
Keyword(s):  
Carbon Dioxide ◽  
Activation Energy ◽  
Room Temperature ◽  
Major Product ◽  
Steric Factor ◽  
Primary Process ◽  
Methyl Radicals ◽  
Low Oxygen ◽  
Secondary Product ◽  
Photo Oxidation

The photo-oxidation of azomethane has been studied at low oxygen pressures (0.02 to 1 mm.) in the temperature range ca. 25 °C. to 161 °C. The primary process in the normal photolysis of azomethane is essentially unaffected by the presence of oxygen. Carbon monoxide is probably a secondary product of the oxidation of methyl radicals. Carbon dioxide formation is quite small, and therefore neither methyl radicals nor CH3N=N—CH2 radicals are oxidized appreciably to carbon dioxide. Nitrous oxide, which is a major product of the oxidation, is most likely formed from the oxidation of CH3N=NCH2 radicals. The suggested mechanism of N2O formation is:[Formula: see text] The reaction of methyl radicals with oxygen was found to proceed with a negligible activation energy and a steric factor of the order of 10−2. Evidence for the occurrence of the reactions[Formula: see text]at room temperature was obtained.

The mechanism of the photolysis of acetamide

1957 ◽  
Vol 239 (1216) ◽  
pp. 1-15 ◽  
Keyword(s):  
Activation Energy ◽  
Steric Factor ◽  
Primary Process ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Subsequent Reaction

An investigation of the photolysis of acetamide has been made using light in the 2500 Å region of the spectrum. The main primary process is the breakdown of the molecule into CH 3 and CONH 2 radicals, but this is probably accompanied by a second process yielding CH 3 CN and H 2 O. The methyl radicals react both with acetamide and with CONH 2 radicals to give methane and recombine to give ethane. The CONH 2 radicals may decompose both spontaneously and thermally to give CO and NH 2 radicals. The subsequent reaction of the NH 2 radicals with acetamide gives ammonia. With acetone as a source of methyl radicals, the activation energy for the abstraction of hydrogen by this radical was found to be 9⋅2 kcal/mole and the steric factor ~ 4 x 10 -4 .

PHOTOLYSIS OF ACETONE – HYDROGEN HLORIDE MIXTURES

1953 ◽  
Vol 31 (2) ◽  
pp. 158-170 ◽  
Author(s):  
R. J. Cvetanović ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Hydrogen Chloride ◽  
Room Temperature ◽  
Steric Factor ◽  
Methyl Radicals ◽  
Strong Suppression ◽  
Upper Limit ◽  
Ethane Formation

The photolysis of acetone – hydrogen chloride mixtures has been investigated at 150 °C. and at room temperature. A strong suppression of ethane formation with a corresponding large increase in the formation of methane results from additions of relatively very small amounts of hydrogen chloride to acetone. The importance of the reactions[Formula: see text]and[Formula: see text]has been demonstrated. The collision yield of reaction (1) at 28 °C. is 2 × 10−4, and, therefore, the upper limit for E1 is 5.1 kcal. per mole. The effects observed at 150° and 28° indicate that, on the assumption of a zero activation energy and a steric factor of unity for combination of methyl radicals, E1 = 2.1 ± 1 kcal. per mole, and P1 is approximately 7 × 10−3.

THE VAPOR-PHASE PHOTOLYSIS OF ACETIC ACID

1955 ◽  
Vol 33 (10) ◽  
pp. 1530-1535 ◽  
Author(s):  
P. Ausloos ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Acetic Acid ◽  
Vapor Phase ◽  
Room Temperature ◽  
Steric Factor ◽  
Primary Process ◽  
Temperature Range ◽  
Abstraction Reaction

The photolysis of acetic acid (CH3COOD) vapor has been investigated in the temperature range from room temperature to 285 °C. Since CH3D formation is independent of temperature, it is certain that the primary process[Formula: see text]occurs to the extent of about 10%. The results are complex and suggest that three other primary processes may occur, viz.[Formula: see text]The abstraction reaction[Formula: see text]is of importance, and the results indicate that it has an activation energy of 10.2 kcal., and a steric factor of the order of 10−3.

PRELIMINARY STUDY OF PHOTOCHEMICAL BEHAVIOR IN THE SYSTEM NITROGEN DIOXIDE – ETHANE

1955 ◽  
Vol 33 (5) ◽  
pp. 843-848
Author(s):  
T. M. Rohr ◽  
W. Albert Noyes Jr.
Keyword(s):  
Nitric Oxide ◽  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Nitrogen Dioxide ◽  
Room Temperature ◽  
Reverse Reaction ◽  
Primary Process ◽  
Photochemical Behavior ◽  
Preliminary Study ◽  
Oxygen Atoms

The addition of ethane to nitrogen dioxide either during exposure to radiation transmitted by pyrex, or afterwards, reduces the amount of oxygen formed. At room temperature this is apparently due to the effectiveness of ethane in promoting the reverse reaction of nitric oxide and oxygen to form nitrogen dioxide. At temperatures over 100° there is a reaction which uses oxygen atoms produced in the primary process. Nitroethane (or nitrosoethane) is formed along with carbon monoxide, carbon dioxide, and some methane. The results suggest that acetaldehyde is an intermediate, but acetaldehyde could not be detected because it would react thermally with nitrogen dioxide. It is not possible to give a complete explanation of the results, but suggestions can be made which might form the basis for later work.

Primary process(es) in the mercury-photosensitized decomposition of dimethyl ether at 2537 Å

1968 ◽  
Vol 46 (16) ◽  
pp. 2693-2697 ◽  
Author(s):  
R. Payette ◽  
M. Bertrand ◽  
Y. Rousseau
Keyword(s):  
Carbon Monoxide ◽  
Quantum Yield ◽  
Light Intensity ◽  
Dimethyl Ether ◽  
Molecular Hydrogen ◽  
Room Temperature ◽  
Primary Process ◽  
Methyl Radicals ◽  
Hydrogen Atoms ◽  
Radical Recombination

The mercury-photosensitized decomposition of dimethyl ether has been studied at room temperature and at pressures ranging from 10 to 200 Torr.The formation of an excited dimethyl ether (DME) molecule has been verified by following the rates of formation of methane, ethane, and carbon monoxide with various ether pressures.The study of the variation of the quantum yield of molecular hydrogen formation with absorbed light intensity at high ether pressures has shown that the primary process involves the dissociation of ether molecules into hydrogen atoms and methoxy methyl radicals:[Formula: see text]The results presented in this paper indicate that the excited DME molecule can originate in a radical recombination between hydrogen atoms and methoxy methyl radicals.

THE GAS PHASE REACTION OF METHYL RADICALS WITH HEXAFLUOROACETONE

1957 ◽  
Vol 35 (10) ◽  
pp. 1216-1224 ◽  
Author(s):  
G. O. Pritchard ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Steric Factor ◽  
Phase Reaction ◽  
Methyl Radicals ◽  
Kcal Mole ◽  
Gas Phase Reaction

The photolytic and thermal decomposition of azomethane in the presence of hexafluoroacetone produces small amounts of fluorinated products, mainly fluoroform. The mechanism of this and related reactions is discussed. It is concluded that the proposed reaction.[Formula: see text]has an activation energy of about 6 kcal./mole, with a steric factor of about 10−5.

REACTION OF OXYGEN ATOMS WITH ACETALDEHYDE

1956 ◽  
Vol 34 (6) ◽  
pp. 775-784 ◽  
Author(s):  
R. J. Cvetanović
Keyword(s):  
Activation Energy ◽  
Nitrous Oxide ◽  
Room Temperature ◽  
Primary Process ◽  
Kcal Mole ◽  
Decomposition Of Nitrous Oxide ◽  
Oxygen Atoms

Reaction of oxygen atoms, produced by mercury photosensitized decomposition of nitrous oxide, with acetaldehyde has been studied at room temperature. The major products of the reaction are water and biacetyl and the only primary process appears to be[Formula: see text]followed by[Formula: see text]and[Formula: see text]At room temperature oxygen atoms react with acetaldehyde 0.7 ± 0.1 times as fast as with ethylene, so that the activation energy of reaction [1] is likely to be close to 3 kcal./mole.

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