THE KINETICS OF THE OXIDATION OF GASEOUS ACETALDEHYDE

1932 ◽  
Vol 7 (2) ◽  
pp. 149-161 ◽  
Author(s):  
W. H. Hatcher ◽  
E. W. R. Steacie ◽  
Frances Howland
Keyword(s):  
Carbon Dioxide ◽  
Formic Acid ◽  
Induction Period ◽  
Reaction Vessel ◽  
Oxidation Products ◽  
Main Reaction ◽  
Chain Mechanism ◽  
Subsequent Reaction ◽  
A Chain ◽  
Kinetics Of

The kinetics of the oxidation of gaseous acetaldehyde have been investigated from 60° to 120 °C. by observing the rate of pressure decrease in a system at constant volume. A considerable induction period exists, during which the main products of the reaction are carbon dioxide, water, and formic acid. The main reaction in the subsequent stages involves the formation of peroxides and their oxidation products. The heat of activation of the reaction is 8700 calories per gram molecule. The indications are that the reactions occurring during the induction period are heterogeneous. The subsequent reaction occurs by a chain mechanism. The chains are initiated at the walls of the reaction vessel, and are also largely broken at the walls.

The gaseous oxidation of aliphatic alcohols. III. n - and iso -propyl alcohols

1960 ◽  
Vol 257 (1290) ◽  
pp. 402-412 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Carbon Monoxide ◽  
Free Radicals ◽  
Induction Period ◽  
Isopropyl Alcohol ◽  
Side Reactions ◽  
Chain Mechanism ◽  
Complete Elimination ◽  
Chain Branching ◽  
A Chain

A study of the gaseous oxidation of n -propyl alcohol (1-propanol) at 264°C shows that, after an induction period during which higher aldehydes and hydrogen peroxide are apparently the only products formed, the pressure starts to rise autocatalytically and methanol, formaldehyde and carbon monoxide become detectable. Additions of higher aldehydes reduce the induction period but the amounts required for its complete elimination are considerably greater than those normally present at the end of the induction period. A chain mechanism is proposed which involves initially abstraction of hydrogen from 1-propanol by HO 2 radicals followed by interaction of the resulting hydroxypropyl radicals with oxygen to yield propionaldehyde. Further reactions of this aldehyde are believed to be responsible for chain-branching and for the formation of the various C 1 products. Isopropyl alcohol (2-propanol) is much less readily oxidized than 1-propanol. At 330°C the main oxidation product is acetone which is formed together with hydrogen peroxide in somewhat smaller quantities. Minor products include methanol, acetaldehyde and formaldehyde. The course of the oxidation of 2-propanol is little affected by additions of acetone or formaldehyde but the induction period is markedly reduced by added acetaldehyde. The chain cycle suggested for the initial stages of oxidation involves attack by HO 2 radicals at the tertiary C─H bond of the alcohol followed by reaction of the resulting free radicals with oxygen to give acetone. The intermediate responsible for chain-branching is believed to be acetaldehyde which is produced by side reactions. C 1 compounds are formed partly by oxidation of this aldehyde and partly by further reactions of acetone.

scholarly journals Further investigations on the kinetics of gaseous oxidation reactions

1930 ◽  
Vol 129 (810) ◽  
pp. 284-299 ◽  
Keyword(s):  
Rate Of Change ◽  
Chain Mechanism ◽  
Oxidation Reactions ◽  
Chain Reactions ◽  
Oxidation Of Methane ◽  
Simple Order ◽  
Oxidation Of Hydrocarbons ◽  
Rate Of Reaction ◽  
A Chain ◽  
Kinetics Of

Investigation of the kinetics of the oxidation of ethylene and of benzene showed that these reactions are peculiar in the following respects. First, the relation between the rate of reaction and concentration is such that the reactions possess no simple “order,” though the nearest integral value for the order is about the third of fourth. The rate increases very rapidly with increasing hydrocarbon concentration, but is relatively little influenced by oxygen; under some conditions oxygen may have a retarding influence. Secondly, the reactions can be slowed down by increasing the surface exposed to the gases. This indicates that the oxidation occurs by a chain mechanism. Thirdly, the rate of change of pressure accompanying the oxidation only attains its full value after an induction period, during which evidently intermediate products are accumulating. Accepting the fact that the oxidations are probably chain reactions, the relation between rate and concentration shown that the chains are much more easily propagated when the intermediate active molecules encounter more hydrocarbon than when they encounter oxygen. Following the view of Egerton, and consistently with previous work on the combination of hydrogen and oxygen, the working hypothesis adopted is that some intermediate peroxidised substance is responsible for the propagation of the chains. This being so, the question arises whether the peculiarities found in the oxidation of hydrocarbons will also be found with substances already containing oxygen. To investigate, therefore, the influence of chemical configuration on the mechanism of oxidation reactions the following series of compounds has been studied CH 4 CH 3 OH HCHO which represent the stages through which Bone and others have shown the oxidation of methane to occur.

scholarly journals The kinetics of the combustion of methane

1936 ◽  
Vol 157 (892) ◽  
pp. 503-525 ◽  
Keyword(s):  
Induction Period ◽  
Time Curve ◽  
Kinetics Of Oxidation ◽  
Reaction Velocity ◽  
Oxidation Of Methane ◽  
Pressure Time ◽  
Reactive Mixture ◽  
A Chain ◽  
Combustion Processes ◽  
Kinetics Of

The kinetics of oxidation of methane at pressures comparable with atmospheric pressure presents many features of great interest and of considerable importance to the elucidation of the nature of combustion processes in general. The facts which have accumulated to date, though fairly precise and definite, require in some cases amplification and further study in view of the realization that combustion has the character of a chain reaction. It has been found that the temperature of ignition of methane, which lies in the region 700-800°C., is dependent on the composition and total pressure of the mixture. For equimolecular mixtures of CH 4 and O 2 , no lower limit phenomena of the kind associated with hydrogen or carbon monoxide ignition have been observed. Below the ignition limit there is a readily measurable reaction velocity, and it was shown by Fort and Hinshelwood that the pressure-time curve is comprised of three distinct parts: ( a ) an induction period of several seconds’ or minutes’ duration, during which almost no reaction can be detected; ( b ) a period of acceleration to a steady velocity, followed by ( c ) a gradual decline of the velocity to zero as the reactants are used up. Fort and Hinshelwood showed that the velocity during the reaction period was much more dependent on the pressure of methane than that of oxygen. They further established the fact that the reaction is almost completely inhibited by packing the vessel with pieces of quartz tubing. Bone and Allum showed that the most reactive mixture consists of methane and oxygen in the ratio 2:1, the induction period being shortest and the reaction velocity greatest for this proportion. It was further found that the reaction is subject to sensi­tization, small quantities of nitrogen peroxide, iodine, or formaldehyde practically removing the induction period and increasing the reaction rate. An analysis of the products of the reaction showed that it followed the general course: CH 4 + 1½ O 2 = 2H 2 O + CO. (I)

scholarly journals THE REACTION OF OXYGEN ATOMS WITH CARBON TETRACHLORIDE

1962 ◽  
Vol 40 (3) ◽  
pp. 486-494 ◽  
Author(s):  
A. Y-M. Ung ◽  
H. I. Schiff
Keyword(s):  
Carbon Dioxide ◽  
Carbon Tetrachloride ◽  
Carbon Atom ◽  
Flow System ◽  
Primary Process ◽  
Chain Mechanism ◽  
Homogeneous Reaction ◽  
Secondary Reactions ◽  
Primary Reactions ◽  
A Chain

The homogeneous reaction between O atoms and CCl4 was studied in a flow system under conditions of complete consumption of atoms, in the presence and in the absence of molecular oxygen. The only products of the reaction are Cl2, CO, CO2, and COCl2. No compounds containing more than one carbon atom were detected. The dependence of the products on CCl4 concentration suggests that the primary reactions are[Formula: see text]which are too slow to consume all the atoms. Carbon dioxide is produced by secondary reactions which are fast enough to consume all the atoms, the most important of which is[Formula: see text]However, the dependence of the ratio (CO2 + COCl2/CO on CCl4 concentration in the presence of O2 indicates other reactions also produce CO2. The rapid disappearance of O atoms in the systems containing O2 suggests a chain mechanism in which Cl2 is mainly converted to the atomic form. Carbon dioxide can then be produced by the sequence[Formula: see text]The rate constant for the primary process was found to be independent of O, O2, and CCl4 concentration and could be represented by the equation[Formula: see text]

scholarly journals Comparative studies of the slow combustion of methane, methyl alcohol, formaldehyde, and formic acid

1936 ◽  
Vol 154 (882) ◽  
pp. 297-328 ◽  
Keyword(s):  
Formic Acid ◽  
Induction Period ◽  
Comparative Studies ◽  
Volume Ratio ◽  
Reaction Vessel ◽  
Hydrocarbon Combustion ◽  
Slow Combustion ◽  
Temperature And Pressure ◽  
Gaseous Hydrocarbons ◽  
Oxygen Ratio

Although the occurrence of a well-defined “induction period” in the slow combustion of gaseous hydrocarbons is now well-established, and something is known about the variation of its duration with such factors as temperature, pressure, mixture-composition, and surface/volume ratio, we are still much in the dark as to its real significance in relation to the mechanism of hydrocarbon-combustion. It has been found that sometimes the induction period may be lengthened by increasing the surface/volume ratio of the reaction vessel, that it may be shortened by raising the temperature or increasing the pressure of the reacting medium, and that for any particular hydrocarbon its duration at a given temperature and pressure depends on the hydrocarbon-oxygen ratio, being always shortest with a 2: 1, i. e ., the alcohol-forming, ratio as was shown in Table III of the Bakerian Lecture of 1932 ( q. v .).

Chain Scission in the Oxidation of Hevea. II.

1956 ◽  
Vol 29 (2) ◽  
pp. 585-592
Author(s):  
E. M. Bevilacqua
Keyword(s):  
Carbon Dioxide ◽  
Acetic Acid ◽  
Natural Rubber ◽  
Formic Acid ◽  
Hydrocarbon Chain ◽  
Chain Scission ◽  
Oxidation Products ◽  
Primary Oxidation

Abstract Oxidation of natural rubber in latex yields two molecules of carbon dioxide, one of formic acid and one of acetic acid for each rupture of the hydrocarbon chain. The yields of these products can be interpreted readily by reference to the structure of the primary oxidation products of 1,5-diolefins established by Bolland and Hughes.

A Highly Durable, Self-Photosensitized Mononuclear Ruthenium Catalyst for CO2 Reduction

Synlett ◽  
2021 ◽  
Author(s):  
Kenji Kamada ◽  
Hiroko Okuwa ◽  
Taku Wakabayashi ◽  
Keita Sekizawa ◽  
Shunsuke Sato ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Reaction Time ◽  
Formic Acid ◽  
Induction Period ◽  
Isotope Labeling ◽  
Co2 Reduction ◽  
Tetradentate Ligand ◽  
Ru Complex ◽  
Carbon Dioxide Co2

A novel mononuclear ruthenium (Ru) complex bearing a PNNP-type tetradentate ligand is introduced here as a self-photosensitized catalyst for the reduction of carbon dioxide (CO2). When the pre-activation of the Ru complex by reaction with a base was carried out, an induction period of catalyst almost disappeared and the catalyst turnover numbers (TONs) over a reaction time of 144 h reached 307 and 489 for carbon monoxide (CO) and for formic acid (HCO2H), respectively. The complex has a long lifespan as a dual photosensitizer and reduction catalyst, due to the sterically bulky and structurally robust (PNNP)Ru framework. Isotope labeling experiments under 13CO2 atmosphere indicate that CO and HCO2H were both produced from CO2.

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