PHOTOLYSIS OF 2, 2′, 4, 4′-TETRADEUTERODIETHYL KETONE

1951 ◽  
Vol 29 (12) ◽  
pp. 1092-1103 ◽  
Author(s):  
M. H. J. Wijnen ◽  
E. W. R. Steacie
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Diethyl Ketone ◽  
Temperature Range ◽  
A Value ◽  
Ethyl Radicals

The photolysis of CH3CD2COCD2CH3 has been studied over a temperature range from 25°C. to 365°C. The results confirm several features of the mechanism, previously proposed for the photolysis of diethyl ketone. It is concluded that disproportionation of ethyl radicals occurs by a "head to tail" mechanism. As activation energy for the reaction[Formula: see text]a value E4 = 8.7 kcal. was found. As activation energy for Reaction (5)[Formula: see text]a value of E5 = 11.7 kcal. was found. An activation energy of ∼ 17 kcal. is estimated for the thermal decomposition of the pentanonyl radical

ADDITION OF ETHYL RADICALS TO ETHYLENE

1957 ◽  
Vol 35 (7) ◽  
pp. 588-594 ◽  
Author(s):  
J. A. Pinder ◽  
D. J. Le Roy
Keyword(s):  
Activation Energy ◽  
Reaction Zone ◽  
Addition Reaction ◽  
Steric Factor ◽  
Square Root ◽  
Temperature Range ◽  
Ethyl Radical ◽  
Ethyl Radicals

The addition of ethyl radicals to ethylene has been studied in the temperature range 58° to 123 °C. The radicals were produced by the mercury photosensitized decomposition of hydrogen in the presence of ethylene, and the rate of the addition reaction was measured in terms of the rate of formation of n-hexane by the combination of ethyl and butyl radicals. Corrections were made for the non-uniformity of radical concentrations in the reaction zone. Assuming a negligible activation energy for the combination of two ethyl radicals, the activation energy for the addition reaction is 5.5 kcal. per mole; the steric factor, relative to the square root of the steric factor for ethyl radical combination, is 5.0 × 10−5.

The thermal decomposition of RDX at temperatures below the melting point. II. Activation energy

1970 ◽  
Vol 23 (4) ◽  
pp. 749 ◽  
Author(s):  
JJ Batten ◽  
DC Murdie
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Melting Point ◽  
Kinetic Parameter ◽  
Arrhenius Equation ◽  
Kcal Mole ◽  
Decomposition Products ◽  
Sample Geometry ◽  
Temperature Range ◽  
Definition Of

The activation energy has been determined in the temperature range 170-198�. If the sample was spread the activation energy was independent of the definition of the kinetic parameter substituted in the Arrhenius equation and was 63 kcal mole-1. In the case of the unspread samples the activation energies of the induction, acceleration, and maximum rates were 49, 43, and 62 kcal mole-1 respectively. The effect that sample geometry has on the activation energy is attributed to gaseous decomposition products influencing the reaction.

ACTIVATION ENERGY FOR CREEP OF TIN

1958 ◽  
Vol 36 (11) ◽  
pp. 1445-1449 ◽  
Author(s):  
L. G. Bonar ◽  
G. B. Craig
Keyword(s):  
Activation Energy ◽  
Steady State ◽  
High Purity ◽  
Steady State Creep ◽  
Temperature Cycling ◽  
Constant Stress ◽  
Creep Tests ◽  
Temperature Range ◽  
A Value

The literature reports values ranging from 8000 to 26,000 cal per g-atom for the activation energy for the creep of tin. The present investigation analyzed the results of constant stress creep tests during steady state creep, and by means of temperature cycling. A value of approximately 9000 cal per g-atom for the creep of high purity tin in the temperature range 300 to 350° K was obtained.

THE PHOTOLYSIS OF AZOETHANE

1958 ◽  
Vol 36 (2) ◽  
pp. 344-353 ◽  
Author(s):  
H. Cerfontain ◽  
K. O. Kutschke
Keyword(s):  
Activation Energy ◽  
Quantum Yield ◽  
Addition Reaction ◽  
Kcal Mole ◽  
A Value ◽  
Ethyl Radicals

The photolysis of azoethane at λ 3660 Å has been reinvestigated. The quantum yield of nitrogen formation was found to be dependent on the azoethane pressure and the temperature, indicating collisional deactivation of excited azoethane molecules.The results confirm the mechanism proposed by Ausloos and Steacie (1). For the activation energy of the addition reaction C2H5 + C2H5N2C2H5 a value of 6.0 ± 0.3 kcal./mole has been obtained, assuming a negligible activation energy for the combination reaction of two ethyl radicals.

Thermoreactivity of Sol-Gel Precursor for ZnO-Based Thin Films

2006 ◽  
Vol 514-516 ◽  
pp. 73-77 ◽  
Author(s):  
Viorica Muşat ◽  
Paula M. Vilarinho ◽  
Regina da Conceição Corredeira Monteiro ◽  
Elvira Fortunato ◽  
E. Segal
Keyword(s):  
Differential Equation ◽  
Thin Films ◽  
Activation Energy ◽  
Thermal Decomposition ◽  
Organic Compounds ◽  
Sol Gel ◽  
Hexagonal Lattice ◽  
Kinetic Investigation ◽  
Temperature Range ◽  
Carbonate Hydroxide

The thermoreactivity of a zinc acetate non-alkoxide solution used for the preparation of ZnO-based thin films was investigated in the temperature range 20-600°C by TG-DTA, XRD and SEM data. We found that the formation in air of ZnO crystallites from the sol-gel precursor occurs above 150°C simultaneously with the decomposition of an intermediary compound, most probably carbonate hydroxide (sclarite and/or hydrozincite). At 200 °C, the crystalline structure is well defined in terms of ZnO hexagonal lattice parameters, although residual organic compounds and water were not yet fully removed and an amorphous phase coexists. A kinetic investigation on the thermal decomposition of sol-gel precursor from DTA data using Kissinger differential equation is also presented. Apparent activation energy values of about. 100 kJ mol-1 corresponding to the nonisothermal decomposition of solid precursors in the temperature range 170-250oC have been found.

THE REACTIONS OF METHYL AND ETHYL RADICALS WITH DIETHYL KETONE

1954 ◽  
Vol 32 (6) ◽  
pp. 593-597 ◽  
Author(s):  
P. Ausloos ◽  
E. W. R. Steacie
Keyword(s):  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Diethyl Ketone ◽  
Temperature Range ◽  
Steric Factors ◽  
Ethyl Radicals

The hydrogen-abstraction reactions of methyl and ethyl radicals from diethyl ketone have been studied in the temperature range 25 to 160 °C. Azomethane and azoethane were used as photochemical sources of methyl and ethyl radicals. The activation energies found were 7.0 and 7.6 kcal., respectively, for the reactions:[Formula: see text][Formula: see text]If the combination of both methyl and ethyl radicals is assumed to occur at every collision, the steric factors for the two reactions are E1 = 7.4 × 10−4, E2 = 7.1 × 10−4.

THE THERMAL DECOMPOSITION OF ETHANE: PART I. INITIATION AND TERMINATION STEPS

1966 ◽  
Vol 44 (4) ◽  
pp. 505-514 ◽  
Author(s):  
M C. Lin ◽  
M. H. Back
Keyword(s):  
Thermal Decomposition ◽  
High Pressure ◽  
Rate Coefficients ◽  
First Order ◽  
Temperature Range ◽  
Order Rate ◽  
Ethyl Radical ◽  
Initiation Reaction ◽  
Ethyl Radicals

The rates of production of methane and butane in the pyrolysis of ethane have been measured over the temperature range 550–620 °C and at pressures of 40–600 mm. At high pressure the rates of formation of both products were first order in ethane, but below 200 mm the first-order rate coefficients decreased. The ratio of methane to butane was consistent with the interpretation that methane is a measure of the initiation reaction and that the combination and disproportionation of ethyl radicals is the main termination step. The order of the decomposition of the ethyl radical with respect to ethane varied between 0.38 and 0.59. The results are discussed in terms of the mechanism of the overall process.

Molecular relaxation in Chitosan films in GHz frequency range

2014 ◽  
Vol 1613 ◽  
pp. 83-88
Author(s):  
Siva Kumar-Krishnan ◽  
Evgen Prokhorov ◽  
Gabriel Luna-Barcenas
Keyword(s):  
Activation Energy ◽  
Low Frequency ◽  
Bound Water ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Temperature Range ◽  
A Value ◽  
Chitosan Films ◽  
First Time

ABSTRACTThe molecular relaxations behavior of chitosan (CS) films in the wide frequency range of 0.1-3x109 Hz (by using three different impedance analyzers) have been investigated in the temperature range of -100C to 120°C using Dielectric Spectroscopy (DS). Additionally to the low frequency molecular relaxations such as α and β relaxations, for the first time, high frequency (1-3 GHz) relaxation process has been observed in the chitosan films. This relaxation exhibits Arrhenius-type dependence in the temperature range of -100 C to 54°C with negative activation energy -2.7 kJ/mol. At temperatures above 54°C, the activation energy changes from -2.7 kJ/mol to +4.4 kJ/mol. Upon cooling, the activation energy becomes negative again with a value of -1.2 kJ/mol. The bound water between chitosan molecules strongly modifies molecular motion and the relaxation spectrum, giving rise to a new relaxation at the frequency at ca. 1 GHz. In situ FTIR analysis has shown that this relaxation related to the changes in vibration of the –OH, NH and –CO functional groups.

THE THERMAL DECOMPOSITION OF DIPHENYLACETIC ACID

1960 ◽  
Vol 38 (8) ◽  
pp. 1271-1276 ◽  
Author(s):  
Margaret H. Back ◽  
A. H. Sehon
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Rate Constant ◽  
Phenylacetic Acid ◽  
Decomposition Reaction ◽  
Temperature Range ◽  
Diphenylacetic Acid

The pyrolysis of diphenylacetic acid was investigated over the temperature range 515-636° C using the toluene-carrier technique. The main products of this system were similar to those formed in the thermal decomposition of phenylacetic acid. The rate constant for the reaction[Formula: see text]was calculated as k′ = 8 × 1012.exp(−52,000/RT) sec−1.The over-all decomposition reaction was found to be partly heterogeneous and, therefore, the activation energy for reaction [1] may be only tentatively identified with D[(C6H5CH)2—COOH].

THE LIQUID PHASE PHOTOLYSIS OF DIETHYL KETONE AND METHYL ETHYL KETONE

1958 ◽  
Vol 36 (2) ◽  
pp. 400-409 ◽  
Author(s):  
P. Ausloos
Keyword(s):  
Liquid Phase ◽  
Quantum Yield ◽  
Methyl Ethyl Ketone ◽  
Methyl Ethyl ◽  
Diethyl Ketone ◽  
Arrhenius Plots ◽  
Temperature Range ◽  
A Value ◽  
Recombination Reactions

The liquid phase photolysis of diethyl ketone has been studied in the temperature range from −35° to 95 °C. The CO quantum yield at 95 °C. was found to be close to unity. At 28 °C. decrease in intensity and addition of heptane led to a substantial increase of the CO and the ethane yields.The methyl ethyl ketone liquid phase photolysis at temperatures between 5° and 75 °C. led to the same observations. Arrhenius plots of RE/RB1/2[K] gave for both compounds a value of 5 kcal./mole.Gas phase studies in the temperature range of 0° to 60 °C. confirmed the low CO quantum yield reported previously and showed evidence for disproportionation and recombination reactions between ethyl and propionyl radicals.

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