The thermal decompositions of carbamates. IV. The reactions of isopropyl N,N-dimethylcarbamate and t-butyl N,N-dimethylcarbamate

1980 ◽  
Vol 33 (3) ◽  
pp. 481 ◽  
Author(s):  
NJ Daly ◽  
F Ziolkowski
Keyword(s):  
Carbon Dioxide ◽  
Gas Phase ◽  
Rate Equations ◽  
First Order ◽  
Temperature Range ◽  
Ammonium Carbamate

The thermal decompositions of isopropyl N,N-dimethylcarbamate and t- butyl N,N-dimethylcarbamate are shown to occur over the temperature range 485-602 K through the reactions Me2NCO2Pri → Me2NH+CO2+MeCH=CH2 Me2NCO2But → Me2NH+CO2+Me2C=CH2 which are described as first-order unimolecular processes for which the rate equations are isopropyl k = 1013.04exp(-181209/8.314T) s-1 �t-butyl k = 1012.87exp(-157904/8.314T) s-1 For both carbamates these rate equations describe the rates of formation of the amine and the appropriate alkene but apparently overestimate the rate of carbon dioxide formation. The discrepancy in the carbon dioxide data is explained in terms of the formation of an amine-carbon dioxide adduct during the condensation stage of the analyses. The adduct is described as an ammonium carbamate which undergoes hydrolysis in solution to free the original amine. The existence of transesterification in the gas phase is ruled out.

The thermal decompositions of carbamates. I. Ethyl N-Methyl-N-phenylcarbamate

1971 ◽  
Vol 24 (12) ◽  
pp. 2541 ◽  
Author(s):  
NJ Daly ◽  
F Ziolkowski
Keyword(s):  
Carbon Dioxide ◽  
Gas Phase ◽  
Rate Constants ◽  
Volume Ratio ◽  
Reaction Vessel ◽  
First Order ◽  
Order Rate

Ethyl N-methyl-N-phenylcarbamate decomposes in the gas phase over the range 329-380� to give N-methylaniline, carbon dioxide, and ethylene. The reaction is quantitative, and is first order in the carbamate. First-order rate constants are described by the equation ������������������� k1 = 1012.44 exp(-45,380/RT) (s-1) and are unaffected by the addition of cyclohexene or by increase in the surface to volume ratio of the reaction vessel. The reaction is considered to be unimolecular and likely to proceed by means of a mechanism of the type represented by the pyrolyses of acetates, xanthates, and carbonates.

scholarly journals Gas-Phase Photocatalytic Oxidation of Dimethylamine: The Reaction Pathway and Kinetics

2007 ◽  
Vol 2007 ◽  
pp. 1-4
Author(s):  
Anna Kachina ◽  
Sergei Preis ◽  
Juha Kallas
Keyword(s):  
Carbon Dioxide ◽  
Gas Phase ◽  
Continuous Flow ◽  
Kinetic Data ◽  
Photocatalytic Oxidation ◽  
Reaction Pathway ◽  
Tubular Reactor ◽  
Order Process ◽  
First Order ◽  
Long Run

Gas-phase photocatalytic oxidation (PCO) and thermal catalytic oxidation (TCO) of dimethylamine (DMA) on titanium dioxide was studied in a continuous flow simple tubular reactor. Volatile PCO products of DMA included ammonia, formamide, carbon dioxide, and water. Ammonia was further oxidized in minor amounts to nitrous oxide and nitrogen dioxide. Effective at 573 K, TCO resulted in the formation of ammonia, hydrogen cyanide, carbon monoxide, carbon dioxide, and water. The PCO kinetic data fit well to the monomolecular Langmuir-Hinshelwood model, whereas TCO kinetic behaviour matched the first-order process. No deactivation of the photocatalyst during the multiple long-run experiments was observed.

The thermal isomerisation of allyl isocyanide

1979 ◽  
Vol 57 (18) ◽  
pp. 2482-2483 ◽  
Author(s):  
Marsha T. J. Glionna ◽  
Huw O. Pritchard
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Gas Phase ◽  
Frequency Factor ◽  
First Order ◽  
Temperature Range

The thermal isomerisation of allyl isocyanide to allyl cyanide has been studied in the gas phase over the temperature range 130–200 °C. The reaction is homogeneous and first order, and at high pressure (20 Torr) has an activation energy of 40.8 ± 0.6 (2sdm) kcal mol−1; the corresponding range of frequency factor is 1014.77±0.30 s−1.

Thermal decomposition of citraconic anhydride

1971 ◽  
Vol 24 (4) ◽  
pp. 771 ◽  
Author(s):  
NJ Daly ◽  
F Ziolkowski
Keyword(s):  
Carbon Dioxide ◽  
Thermal Decomposition ◽  
Gas Phase ◽  
Rate Constant ◽  
Arrhenius Equation ◽  
Volume Ratio ◽  
Reaction Vessel ◽  
First Order ◽  
First Order Kinetics ◽  
Citraconic Anhydride

Citraconic anhydride decomposes in the gas phase over the range 440- 490� to give carbon dioxide, carbon monoxide, and propyne which undergoes some polymerization to trimethylbenzenes. The decomposition obeys first-order kinetics, and the Arrhenius equation ������������������� k1 = 1015.64 exp(-64233�500/RT) (s-1) describes the variation of rate constant with temperature. The rate constant is unaffected by the addition of isobutene or by increase in the surface/volume ratio of the reaction vessel. The reaction appears to be unimolecular and if a diradical intermediate is involved it may not be fully formed in the transition state.

Catalysed gas phase decompositions. XXV. 2,2-Dimethoxypropane and acetic acid

1973 ◽  
Vol 26 (4) ◽  
pp. 761 ◽  
Author(s):  
DA Kairaitis ◽  
VR Stimson ◽  
JW Tilley
Keyword(s):  
Acetic Acid ◽  
Gas Phase ◽  
Arrhenius Equation ◽  
Hydrogen Halide ◽  
First Order ◽  
Temperature Range

Acetic acid catalyses the decomposition of 2,2-dimethoxypropane into methyl isopropenyl ether and methanol in the temperature range 314- 400�. The reaction is first order in the pressure of each reactant, and the variation of rate with temperature is given by the Arrhenius equation: ������������ k2 = 1012.90�0.15exp(-30830�420/1.987T) s-1 ml mol-1 The reaction is believed to be homogeneous and molecular. This is the first example of this series where the catalyst has been other than a hydrogen halide.

The reaction of methanol vapour with silver(I) oxide

1964 ◽  
Vol 17 (5) ◽  
pp. 529
Author(s):  
JA Allen
Keyword(s):  
Carbon Dioxide ◽  
Thermal Decomposition ◽  
Carbon Monoxide ◽  
Gas Phase ◽  
Kinetic Data ◽  
Kcal Mole ◽  
Collision Model ◽  
Temperature Range ◽  
Methanol Vapour ◽  
The Mean

The reaction of methanol with silver(I) oxide has been studied in the temperature range 56.5-78.4�. For complete reduction of the oxide at 78.4�, the available oxygen is fully accounted for by the products, formaldehyde, formic acid, carbon monoxide, carbon dioxide, and water. In the temperature range 56.5-70.2� the net measured rates of formation of these products are expressed by equations of the form, ������������������ rate = Aexp(-E/RT), and the kinetic data are interpreted as the consecutive formation of the products on the surface without complete desorption to the gas phase between each step. For the dominant product, carbon dioxide, at the mean temperature the values of A and E are 1028.5 μg oxygen per minute and 41.3 kcal mole-1 respectively. The former is interpreted in terms of a simple collision model and the latter compared with values obtained for the thermal decomposition of the oxide.

Interaction of H2O, O2 and H2 with Proton Conducting Oxides Based on Lanthanum Scandates

2019 ◽  
pp. 88-100
Author(s):  
A. S. Farlenkov ◽  
N. A. Zhuravlev ◽  
Т. A. Denisova ◽  
М. V. Ananyev
Keyword(s):  
Water Vapor ◽  
Partial Pressure ◽  
Gas Phase ◽  
Molecular Hydrogen ◽  
Proton Magnetic Resonance ◽  
Partial Pressure Of Oxygen ◽  
Proton Conducting ◽  
Conducting Oxides ◽  
Temperature Range ◽  
Apparent Level

The research uses the method of high-temperature thermogravimetric analysis to study the processes of interaction of the gas phase in the temperature range 300–950 °C in the partial pressure ranges of oxygen 8.1–50.7 kPa, water 6.1–24.3 kPa and hydrogen 4.1 kPa with La1–xSrxScO3–α oxides (x = 0; 0.04; 0.09). In the case of an increase in the partial pressure of water vapor at a constant partial pressure of oxygen (or hydrogen) in the gas phase, the apparent level of saturation of protons is shown to increase. An increase in the apparent level of saturation of protons of the sample also occurs with an increase in the partial pressure of oxygen at a constant partial pressure of water vapor in the gas phase. The paper discusses the causes of the observed processes. The research uses the hydrogen isotope exchange method with the equilibration of the isotope composition of the gas phase to study the incorporation of hydrogen into the structure of proton-conducting oxides based on strontium-doped lanthanum scandates. The concentrations of protons and deuterons were determined in the temperature range of 300–800 °C and a hydrogen pressure of 0.2 kPa for La0.91Sr0.09ScO3–α oxide. The paper discusses the role of oxygen vacancies in the process of incorporation of protons and deuterons from the atmosphere of molecular hydrogen into the structure of the proton conducting oxides La1–xSrxScO3–α (x = 0; 0.04; 0.09). The proton magnetic resonance method was used to study the local structure in the temperature range 23–110 °C at a rotation speed of 10 kHz (MAS) for La0.96Sr0.04ScO3–α oxide after thermogravimetric measurements in an atmosphere containing water vapor, and after exposures in molecular hydrogen atmosphere. The existence of proton defects incorporated into the volume of the investigated proton oxide from both the atmosphere containing water and the atmosphere containing molecular hydrogen is unambiguously shown. The paper considers the effect of the contributions of the volume and surface of La0.96Sr0.04ScO3–α oxide on the shape of the proton magnetic resonance spectra.

Photocatalytic Discolouration of Solutions of Reactive Dyes in the Presence of H2O2

1995 ◽  
Vol 30 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Deng Nansheng ◽  
Tian Shizhong ◽  
Xia Mei
Keyword(s):  
Photochemical Reaction ◽  
Uv Light ◽  
Reactive Dyes ◽  
Solar Light ◽  
Rate Equations ◽  
Oh Radical ◽  
Test Results ◽  
Dye Molecules ◽  
First Order ◽  
Dye Solutions

Abstract Tests for the photocatalytic degradation of solutions of three reactive dyes, Red M-5B, Procion Blue MX-R and Procion Black H-N, in the presence of H2O2 were carried out. When the solutions of the three reactive dyes were irradiated by UV or solar light, the colour of the solutions disappeared gradually. A statistical analysis of the test results indicated a linear relation between the concentration of dyes and the time of irradiation. The discolouration reaction of the solutions was of the first order. Rate equations for the discolouration reactions of dye solutions were developed. The dark reactions or the dye solutions containing H2O2 were very slow, illustrating that the photochemical reaction played a very important role. It was demonstrated that UV light and solar light (300 to 380 nm) photolyzes the HO and that the resulting OH radical reacts with the dye molecules and destroys the chromophore.

Application of Disk Aerators to Recarbonation of Alkaline Wastewater from Wet Gasification of Carbide

1991 ◽  
Vol 24 (7) ◽  
pp. 277-284 ◽  
Author(s):  
E. Gomólka ◽  
B. Gomólka
Keyword(s):  
Carbon Dioxide ◽  
Liquid Phase ◽  
Gas Phase ◽  
Flue Gas ◽  
Carbonic Acid ◽  
Low Cost ◽  
Flue Gases ◽  
Carbon Dioxide Content ◽  
Patent Claim ◽  
Phase Dispersion

Whenever possible, neutralization of alkaline wastewater should involve low-cost acid. It is conventional to make use of carbonic acid produced via the reaction of carbon dioxide (contained in flue gases) with water according to the following equation: Carbon dioxide content in the flue gas stream varies from 10% to 15%. The flue gas stream may either be passed to the wastewater contained in the recarbonizers, or. enter the scrubbers (which are continually sprayed with wastewater) from the bottom in oountercurrent. The reactors, in which recarbonation occurs, have the ability to expand the contact surface between gaseous and liquid phase. This can be achieved by gas phase dispersion in the liquid phase (bubbling), by liquid phase dispersion in the gas phase (spraying), or by bubbling and spraying, and mixing. These concurrent operations are carried out during motion of the disk aerator (which is a patent claim). The authors describe the functioning of the disk aerator, the composition of the wastewater produced during wet gasification of carbide, the chemistry of recarbonation and decarbonation, and the concept of applying the disk aerator so as to make the wastewater fit for reuse (after suitable neutralization) as feeding water in acetylene generators.

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