Gas-phase oxidation of butene-2

The gas-phase thermal oxidation of butene-2 has been examined over the temperature range 289 to 395°C. No difference in behaviour of the cis and trans forms could be detected. At the higher temperatures the reaction resembled that of the oxidation of propylene in the shape of the pressure-time curve and in the identity of many of the reaction products. At the lower temperatures a decrease in pressure partly due to peroxide formation followed the induction period, and by the end of this time much of the initial oxygen had been consumed. At all temperatures excess olefin produced an apparent inhibiting effect manifested by a decreased yield of carbon monoxide and a fall-off in the maximum rate of pressure change and total pressure change. Reaction processes are discussed, and it is suggested that a peroxide precedes the formation of acetaldehyde. Branching occurs largely through reaction of acetyl radicals produced from the acetaldehyde. The inhibiting effects produced by excess olefin are attributed to the replacement of reactive radicals by the less reactive allylic-type radicals, and the addition reactions of olefin at higher olefin concentrations lead to polymerization and a low or negative overall pressure change.

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Chloroform as an accelerator of propane oxidation

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1963.0141 ◽

1963 ◽

Vol 274 (1358) ◽

pp. 413-426 ◽

Cited By ~ 3

Keyword(s):

Gas Phase ◽

Maximum Rate ◽

Isotopic Exchange ◽

Pressure Change ◽

Product Formation ◽

Pressure Measurements ◽

Chain Mechanism ◽

Phase Oxidation ◽

Gas Phase Oxidation ◽

Simple Chain

Chloroform and the other chloromethanes, except carbon tetrachloride, accelerate the gas-phase oxidation of propane in the 'low-temperature' region. The relation of pressure change to reactant consumption and final product formation is not significantly modified in the catalyzed reaction, which can still be followed by pressure measurements. The value of the maximum rate in the presence of chloroform is given fairly closely by the expression (( ρ max .) [CHCL 3 ])/( ρ max .) 0 = 1 + constant x [CHCI 3 ]/[ R H]. The form of this suggests that, in the rate-determining steps, chloroform and paraffin are involved in analogous processes, and the key step is postulated to be R O 2 · + CHCI 3 → R OOH + CCl 3 · which re-inforces the reaction R O 2 · + R H → R OOH + R · in competing with those steps normally leading to degradation of R O 2 · radicals. Since little or no isotopic exchange occurs when CDCl 3 is used in place of CHCl 3 , the radical CCl 3 · does not regenerate chloroform, but initiates chains of the type CCl 3 ·→ ·CCl 2 · + Cl·, Cl· + R H → HCl + R · A slow consumption of chloroform (the oxidation of which is unimportant in the absence of propane) occurs, together with a slow build-up of hydrogen chloride. With certain approximations, a simple chain mechanism reproduces the experimental kinetic formula.

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Gas-phase oxidation of hexene-1

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1958.0046 ◽

1958 ◽

Vol 244 (1238) ◽

pp. 345-354 ◽

Cited By ~ 4

Keyword(s):

Oxygen Consumption ◽

Gas Phase ◽

Maximum Rate ◽

Reaction Rate ◽

Pressure Change ◽

Early Stages ◽

Unusual Form ◽

Phase Oxidation ◽

Rate Of Oxygen Consumption ◽

Gas Phase Oxidation

An investigation has been made of the oxidation of hexene-1 at 263°C. The unusual form of dependency of reaction rate on hydrocarbon pressure obtained when the maximum rate of pressure change is used as a measure of reaction rate is explained by the fact that much of the oxygen is consumed before the maximum rate of pressure change is attained. This, and the observation that the maximum rate of oxygen consumption exhibits a different dependence on hexene concentration compared with the maximum rate of pressure change confirm that maximum rate of pressure change is an invalid measure of reaction rate. Analyses have been made for certain intermediates and products throughout the course of the reaction, and it has been possible to explain many of the experimental features in terms of ideas previously propounded. A decrease in pressure which in many experiments precedes the rapid increase in pressure is attributed to polymerization reactions which predominated over oxidative degradations in the early stages of the reaction, particularly when the olefin is present in excess.

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The slow combustion of cyclo pentane - II. Analytical results and mechanism

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1958.0106 ◽

1958 ◽

Vol 246 (1244) ◽

pp. 64-77 ◽

Cited By ~ 3

Keyword(s):

Carbon Dioxide ◽

Gas Phase ◽

Maximum Rate ◽

Pressure Change ◽

Reaction Scheme ◽

Elementary Reactions ◽

Slow Combustion ◽

Initial Oxygen ◽

Increasing Temperature ◽

True Measure

The products of the oxidation of cyclo pentane in the gas phase at around 400 °C in an uncoated vessel were water, carbon monoxide and carbon dioxide with smaller amounts of hydrogen, methane, ethylene, propylene, cyclo pentane, formaldehyde, higher aldehydes (mainly acetaldehyde) and acids. It was confirmed that the pressure change was true measure of the extent of reaction. The pressures of higher aldehydes and unsaturates rose to a maximum at about the time of the maximum rate, and the variation of these maximum pressures with initial oxygen and cyclo pentane pressures was investigated. Addition of formaldehyde initially had little effect on the reaction, but addition of higher aldehydes reduced the induction period and increased the maximum rate. The CO/CO 2 ratio increased with increasing temperature and cyclo pentane pressure and was much greater with the boric-acid-coated vessel. Also using this vessel peroxidic material was detected in the products. Higher aldehydes were probably the substances responsible for delayed branching. The various elementary reactions which may have occurred in the system are discussed and a reaction scheme which can explain the products and to some extent the kinetic results is proposed. Cyclo pentylperoxy (C 5 H 9 O 2 ) radicals were probably important both in propagating and terminating the chains.

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The gas-phase reaction of acetic acid with hydrogen bromide. The effect of isobutene

Australian Journal of Chemistry ◽

10.1071/ch9710765 ◽

1971 ◽

Vol 24 (4) ◽

pp. 765 ◽

Cited By ~ 1

Author(s):

NJ Daly ◽

MF Gilligan

Keyword(s):

Acetic Acid ◽

Gas Phase ◽

Initial Rate ◽

Hydrogen Bromide ◽

Pressure Change ◽

Mesityl Oxide ◽

Phase Reaction ◽

Thermal Reactions ◽

Pressure Time ◽

Molecular Reaction

Addition of isobutene to reaction mixtures of acetic acid and hydrogen bromide brings about a lowering in the initial rate of pressure change. The lowering is proportional to the pressure of isobutene and is explained in terms of a molecular reaction producing mesityl oxide. Mesityl oxide is formed steadily throughout the course of the reaction in quantities proportional to the pressure of isobutene. The quantities of mesityl oxide detected are less than those required to account quantitatively for the lowering of dp/dt, but the presence of the products of the thermal reactions of mesityl oxide, and the minima observed in the pressure-time curves at 407� show that the discrepancies can be accounted for in terms of the polymerization undergone by mesityl oxide in the presence of hydrogen bromide. The reaction appears analogous to the formation of mesityl oxide by the acetylation of isobutene in solution.

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Tetrachloroethylene as an accelerator of propane oxidation

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1964.0022 ◽

1964 ◽

Vol 277 (1369) ◽

pp. 279-288 ◽

Cited By ~ 1

Keyword(s):

Gas Phase ◽

Maximum Rate ◽

Pressure Change ◽

Product Formation ◽

Chain Mechanism ◽

Phase Oxidation ◽

Gas Phase Oxidation ◽

Simple Chain ◽

Catalyzed Reactions ◽

Key Steps

Tetrachloroethylene and the other chloroethylenes accelerate the gas-phase oxidation of propane in the `low-temperature ’ region, the relation of pressure change to reactant consumption and final product formation being not significantly modified in the catalyzed reaction. The value of the maximum rate in the presence of tetrachloroethylene is given fairly closely by the expression (ρmax.) [C 2 Cl 4 ] / (ρmax.) 0 = 1 + constant x [C 2 Cl 4 ]. The form of this differs from th at found in the chloroform-catalyzed reaction, (ρmax.) [CHCl 3 ] / (ρmax.) 0 = 1 + constant x [CHCl 3 ]/[ Pr H], and suggests th at the key steps are R O · 2 +CCl 2 = CCl 2 ⇌ ROOCCl 2 CCl · 2 R OOCCl 2 CCl · 2 + R H → Cl + ... A slow formation of hydrogen chloride occurs during reaction. A simple chain mechanism approximately reproduces the experimental kinetic formula. Some results for trichloroethylene indicate a type of behaviour intermediate between the chloroform- and tetrachloroethylene-catalyzed reactions.

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COMPUTER MODELING OF CHEMICAL EQUILIBRIUMS IN WO3–H2O SYSTEM

Energy Technologies & Resource Saving ◽

10.33070/etars.4.2017.06 ◽

2017 ◽

pp. 35-48 ◽

Cited By ~ 1

Author(s):

V.P. Bondarenko ◽

O.O. Matviichuk

Keyword(s):

Transition Temperature ◽

Gas Phase ◽

Single Phase ◽

Reference Data ◽

Maximum Amount ◽

Reaction Products ◽

Influence Of Temperature ◽

Equilibrium Chemical ◽

Program Data ◽

Good Agreement

Detail investigation of equilibrium chemical reactions in WO3–H2O system using computer program FacktSage with the aim to establish influence of temperature and quantity of water on formation of compounds of H2WO4 and WO2(OH)2 as well as concomitant them compounds, evaporation products, decomposition and dissociation, that are contained in the program data base were carried out. Calculations in the temperature range from 100 to 3000 °С were carried out. The amount moles of water added to 1 mole of WO3 was varied from 0 to 27. It is found that the obtained data by the melting and evaporation temperatures of single-phase WO3 are in good agreement with the reference data and provide additionally detailed information on the composition of the gas phase. It was shown that under heating of 1 mole single-phase WO3 up to 3000 °С the predominant oxide that exist in gaseous phase is (WO3)2. Reactions of it formation from other oxides ((WO3)3 and (WO3)4) were proposed. It was established that compound H2WO4 is stable and it is decomposed on WO3 and H2O under 121 °C. Tungsten Oxide Hydrate WO2(OH)2 first appears under 400 °С and exists up to 3000 °С. Increasing quantity of Н2О in system leads to decreasing transition temperature of WO3 into both liquid and gaseous phases. It was established that adding to 1 mole WO3 26 mole H2O maximum amount (0,9044–0,9171 mole) WO2(OH)2 under temperatures 1400–1600 °С can be obtained, wherein the melting stage of WO3 is omitted. Obtained data also allowed to state that that from 121 till 400 °С WO3–Н2O the section in the О–W–H ternary system is partially quasi-binary because under these temperatures in the system only WO3 and Н2O are present. Under higher temperatures WO3–Н2O section becomes not quasi-binary since in the reaction products WO3 with Н2O except WO3 and Н2O, there are significant amounts of WO2(OH)2, (WO3)2, (WO3)3, (WO3)4 and a small amount of atoms and other compounds. Bibl. 12, Fig. 6, Tab. 5.

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