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.

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.

Radiation-induced oxidation of 2-propanol by hydrogen peroxide in aqueous solutions

1970 ◽  
Vol 48 (8) ◽  
pp. 1232-1238 ◽  
Author(s):  
C. E. Burchill ◽  
I. S. Ginns
Keyword(s):  
Aqueous Solution ◽  
Hydrogen Peroxide ◽  
Aqueous Solutions ◽  
Lower Limit ◽  
Alcohol Concentration ◽  
Chain Mechanism ◽  
Radiation Induced ◽  
A Chain ◽  
High Yields ◽  
Radical Conversion

The radiation-induced oxidation of 2-propanol by hydrogen peroxide in neutral deaerated aqueous solution has been investigated. 2-Propanol is oxidized to acetone, and hydrogen peroxide reduced in stoichiometrically equivalent high yields. The yields are independent of hydrogen peroxide concentration in the range 5 × 10−2 to 10−3 M and linearly dependent on alcohol concentration in the range 0.13 to 1.05 M. The reaction yields increased with decreasing dose rate.The results are explained by a chain mechanism in which initiation occurs via H-atom abstraction from 2-propanol to form either (CH3)2ĊOH (1) or CH3 CHOH ĊH2 (2). 1 reacts with H2O2 in a chain propagating reaction[Formula: see text]2 may abstract the α hydrogen from the parent alcohol[Formula: see text]or undergo bimolecular termination. A lower limit of 53 ± 101mole−1 s−1 is estimated for the rate constant for this radical conversion reaction.

scholarly journals The thermal decomposition of acetaldehyde

1935 ◽  
Vol 149 (867) ◽  
pp. 355-359 ◽  
Keyword(s):  
Thermal Decomposition ◽  
Carbon Monoxide ◽  
Condensation Reaction ◽  
Pressure Increase ◽  
Chain Mechanism ◽  
Vessel Size ◽  
Previous Evidence ◽  
Gaseous Products ◽  
A Chain ◽  
Effect Of Surface

This paper contains a more detailed study than has hitherto been made of the effect of surface and vessel size on the thermal decomposition of acetaldehyde. This was desirable in view of the suggestion recently made that the reaction might take place by a chain mechanism, and also because the validity of the previous evidence that the reaction is homogeneous has been called in question. In an unpacked silica between 500° and 600° the reaction is attended by a pressure increase which is about 98% of that corresponding to the equation CH 3 CHO = CH 4 + CO, and the gaseous products consists of equal parts of carbon monoxide and methane. When a packed vessel with very large surface is used the pressure increase is rather less than the theoretical, indicating that some condensation reaction occurs which is probably heterogeneous in contrast with the principal decomposition.

The Chlorine Atom Sensitized Oxidation and the Ozonolysis of C2Cl4

1974 ◽  
Vol 52 (23) ◽  
pp. 3852-3862 ◽  
Author(s):  
Eckart Mathias ◽  
Eugenio Sanhueza ◽  
I. C. Hisatsune ◽  
Julian Heicklen
Keyword(s):  
Free Radicals ◽  
Chain Length ◽  
Chlorine Atom ◽  
Chain Process ◽  
Chain Mechanism ◽  
A Chain ◽  
A Minor ◽  
Long Chain

The chlorine atom initiated oxidation of C2Cl4 was studied both in the absence and presence of O3 at 24 and 32 °C. In the absence of O3, the products are CCl3CCl(O) and CCl2O, and they are produced in a long-chain process in a ratio of 2.5 at 24 °C and 3.0 at 32 °C. The product producing step involves the decay of C2Cl5O radicals[Formula: see text]The ratio k6a/k6b is 5.0 at 24 °C and 6.0 at 32 °C since CCl3 reacts with O2 to produce another CCl2O molecule. In the presence of O3 the ratio Φ{CCl3CCl(O)}/Φ{CCl2O} drops, [Formula: see text] is produced, and the chain length is reduced. The change in Φ{CCl3CCl(O)}/Φ{CCl2O} is a function of [O3]/[O2] and is attributed to the additional reactions[Formula: see text]The epoxide yield is a function of [C2Cl4]/[O3] and is attributed to the reaction of ClO with C2Cl4. The ClO is produced by the reaction of Cl• with O3[Formula: see text]which competes with[Formula: see text]The ratio k2/kl0 = 6.7. The reduction in yield as O3 is added results from the terminating reaction[Formula: see text]The ClO2 reacts further with O3 to produce Cl2O7.The reaction of O3 with C2Cl4 at 24 °C also produces mainly CCl3CCl(O) and CCl2O with [Formula: see text] as a minor product. Other minor products detected after extended conversions included Cl2, CO, and CO2. However c-C3Cl6 was not found. The ratio [CCl3CCl(O)]/[CCl2O] is < 1. Moreover, the addition of O2 retarded the reaction, indicating a long chain mechanism in which both free radicals (species with an odd number of electrons) and CCl2 were absent. A diradical chain mechanism is presented which explains the main features. The chain step is the addition of CCl2O2 to C2Cl4[Formula: see text]The adduct then reacts with O3 in a chain regenerating step or with O2 in a chain terminating step.

scholarly journals The combination of hydrogen and oxygen photosensitised by nitrogen peroxide

1933 ◽  
Vol 139 (837) ◽  
pp. 147-162 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Spectroscopic Study ◽  
Gas Phase ◽  
Alternative Form ◽  
Chain Mechanism ◽  
Homogeneous Reaction ◽  
Chain Reaction ◽  
Chain Reactions ◽  
Temperature And Pressure ◽  
A Chain

The homogeneous reaction between hydrogen and oxygen has been proved by the work of Hinshelwood, of Haber, and of Semenoff to be a chain reaction, which under certain conditions of temperature and pressure may pass over into an explosive combination. The reaction is subject to the kinetics characteristic of certain types of chain reactions, in that, for any particular temperature, there are upper and lower pressure limits for explosion, the former controlled by deactivation of the chains in the gas phase, and the latter by their termination at the surface. The conditions further point to a branching chain mechanism; below 300°C. there is no observable propagation of reaction chains. These facts seem to be well represented by the scheme of Bonhoeffer and Haber, which was put forward on the basis of a spectroscopic study of the dissociation of steam at high temperatures. H + H 2 + O 2 = HO + H 2 O + 102,000 cals. (1) HO + H 2 = H 2 O + H + 10,000 cals. (2) reaction (1) sometimes taking the alternative form H + H 2 + O 2 = OH + OH + H - 2000 cals. (1a) which accounts for the branching of the chains. Reaction (2) does not occur appreciably at temperatures below 300°C., but the OH radicles yield hydrogen peroxide which may be detected.

The gaseous oxidation of aliphatic alcohols II. Ethyl alcohol: the products formed in the later stages of reaction

1957 ◽  
Vol 242 (1231) ◽  
pp. 516-533 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Carbon Monoxide ◽  
Induction Period ◽  
Maximum Rate ◽  
Critical Concentration ◽  
Pressure Rise ◽  
Pressure Change ◽  
Maximum Pressure ◽  
Acetaldehyde Oxidation ◽  
Pyrolytic Reaction

In the slow oxidation of ethanol between 270 and 370° C there is an induction period during which a critical concentration of acetaldehyde accumulates without pressure change. This paper describes detailed analytical studies of the reaction following the induction period. Pressure increase in general provides a good measure of reactant consumption except in the late stages of reaction. The yields of acetaldehyde and hydrogen peroxide, which are initially high, fall off as the pressure rises, while those of methanol, formaldehyde, carbon monoxide and water increase. Formation of carbon monoxide closely parallels that of methanol at 295° C. In ethanol-rich mixtures oxygen consumption ceases abruptly after the maximum rate is reached, and is superseded by a pyrolytic reaction in which carbon monoxide and methane are formed in equivalent amounts. The maximum pressure of acetaldehyde is linearly dependent on initial ethanol concentration and is sensibly independent of oxygen; the same behaviour is shown by the maximum rate of pressure rise. Small quantities of added acetaldehyde markedly shorten the induction period, but have little effect on the subsequent stages of reaction; larger amounts of acetaldehyde increase the reaction rate. Added methanol retards the reaction, apparently by stabilizing radicals formed from acetaldehyde oxidation. The yields of peroxides are affected by temperature and, markedly, by changes in the nature and extent of the surface, but the essential features of the reaction mechanism persist under wide series of conditions. The analytical results are well accounted for by a mechanism in which acetaldehyde, formed (with hydrogen peroxide) in primary chains, is oxidized in a branching chain cycle; this process leads, through formation of CH 3 radicals, to the C 1 compounds observed.

THE KINETICS OF THE OXIDATION OF FERROUS ION BY HYDROGEN PEROXIDE IN THE PRESENCE OF DISSOLVED HYDROGEN AND CARBON MONOXIDE

1957 ◽  
Vol 35 (5) ◽  
pp. 437-443 ◽  
Author(s):  
T. J. Hardwick
Keyword(s):  
Hydrogen Peroxide ◽  
Carbon Monoxide ◽  
Kinetic Scheme ◽  
Ferrous Ion ◽  
Side Reactions ◽  
Hydroperoxyl Radical ◽  
Relative Value ◽  
Ion Production ◽  
Dissolved Hydrogen ◽  
Kinetics Of

An expression has been derived for the rate of ferric ion production in the ferrous ion – hydrogen peroxide reaction in aqueous solution containing dissolved hydrogen and oxygen. It involves the relative value of the rate constants for the intermediate reactions[Formula: see text]The effects of side reactions involving the intermediate hydroperoxyl radical are considered. The rate calculated from the derived expression agrees with that measured experimentally (±2%). When carbon monoxide is used instead of hydrogen, the kinetic scheme and rate expression are the same. The agreement between experimental and calculated rates is within ±2%.

scholarly journals The mechanism of chain breaking in the thermal decomposition of ethane

1938 ◽  
Vol 167 (931) ◽  
pp. 439-446 ◽  
Author(s):  
J. E. Hobbs ◽  
Cyril Norman Hinshelwood
Keyword(s):  
Nitric Oxide ◽  
Thermal Decomposition ◽  
Free Radicals ◽  
Chain Length ◽  
Chain Mechanism ◽  
Collision Process ◽  
Ethane Molecule ◽  
Chain Breaking ◽  
The Mean ◽  
A Chain

The decomposition of ethane in the neighbourhood of 600° occurs largely by a chain mechanism in which free radicals are formed. In the course of experiments on the inhibition of the reaction by nitric oxide, Staveley (1937) found that the mean chain length diminished with increasing ethane pressure. From this he reached the conclusion that the chains were broken predominantly by a ternary collision process involving two radicles and an ethane molecule. The important question whether chains are ended by binary or by ternary collisions can be approached in another way, the exploration of which is described in the following pages.

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