Mono, Di and Trifunctional Cyclic Organic Peroxides: The Effect of Substituents and Ring Size on their Thermolysis in 1,4-dioxan

2013 ◽  
Vol 66 (9) ◽  
pp. 1080 ◽  
Author(s):  
Rosa Nesprias ◽  
Gladys Eyler ◽  
Adriana Cañizo
Keyword(s):  
Thermal Decomposition ◽  
Statistical Treatment ◽  
Activation Parameters ◽  
Decomposition Reaction ◽  
Order Kinetic ◽  
Organic Peroxides ◽  
Solvent Interaction ◽  
Kinetic Behaviour ◽  
First Order ◽  
Thermal Stability Of

The thermal decomposition reaction of cyclic organic peroxides was studied in 1,4-dioxan at initial concentrations between ~10–4 and 10–2 mol L–1 and at a temperature interval between 100 and 170°C, according to the thermal stability of each compound. The kinetic behaviour observed in all systems studied follows a pseudo first order kinetic law up to at least ~86 % of peroxide conversion. An important substituent effect is operative on the rate constant values and consequently on the activation parameters of the thermal decomposition reaction. The application of different treatments (compensation affect or a statistical treatment) on the kinetic data shows the existence of two sets of cyclic peroxides with comparable kinetic behaviour. Different peroxide–solvent interaction mechanisms can be considered within each series.

scholarly journals Thermal decomposition of 3,6-diphenyl-1,2,4,5-tetroxane in nitromethane solution

2018 ◽  
Vol 15 (2) ◽  
pp. 6306-6310
Author(s):  
Nelly Lidia Jorge ◽  
Alexander German Bordón ◽  
Andrea Natalia Pila ◽  
Mariela Ines Profeta ◽  
Maria Josefa Jorge ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Benzoic Acid ◽  
Activation Enthalpy ◽  
Decomposition Reaction ◽  
Activation Entropy ◽  
Order Kinetic ◽  
Stepwise Mechanism ◽  
First Order ◽  
Mechanism Of Decomposition ◽  
Organic Products

The thermal decomposition reaction of benzaldehyde diperoxide (DFT; 0.001 mol L-1) in nitromethane solution studied in the temperature range of 130.0-166.0 °C, follows a first-order kinetic law up to at least 60% DFT conversion. The organic products observed were benzaldheyde and benzoic acid. A stepwise mechanism of decomposition was proposed where the first step is the homolytic unimolecular rupture of the O-O bond. The activation enthalpy and activation entropy for DFT in nitromethane were calculated (DH# = 106.3 ± 1.0 kJ mol-1 and DS# = -58.6 ± 1.1 J mol-1K-1) and compared with those obtained in other solvents to evaluate the solvent effect.

Thermal processing of sewage sludge by drying, pyrolysis, gasification and combustion

2001 ◽  
Vol 44 (10) ◽  
pp. 333-339 ◽  
Author(s):  
P. Stolarek ◽  
S. Ledakowicz
Keyword(s):  
Thermal Decomposition ◽  
Sewage Sludge ◽  
Kinetic Parameters ◽  
Thermal Processing ◽  
Combustion Process ◽  
Order Kinetic ◽  
Municipal Sludge ◽  
Pyrolysis Kinetics ◽  
Exponential Factor ◽  
First Order

Thermal processing of sewage sludge including drying, pyrolysis and gasification or combustion may be an alternative to other ways of utilising it. In this paper thermogravimetric analysis (TGA) was employed in the investigation of thermal decomposition of sewage sludge. The kinetic parameters of drying, pyrolysis and gasification or combustion of sewage sludge have been determined in an inert-gas (argon) and additionally some series of the sludge decomposition experiments have been carried out in air, in order to compare pyrolysis and combustion. The pyrolysis char has been gasified with carbon dioxide. A typical approach to the kinetics of thermal decomposition of a solid waste is to divide the volatile evolution into a few fractions (lumps), each of which is represented by a single first-order reaction. If these lumps are assumed to be non-interacting and evolved by independent parallel reactions the first-order kinetic parameters such as activation energy Ei and pre-exponential factor Ai can be determined from mathematical evaluation of TG or DTG curves. The object of our investigations was a municipal sludge from the two wastewater treatment plants (WTP) in Poland. The experiments have been carried out in the thermobalance Mettler-Toledo type TGA/SDTA851 LF, in the temperature range 30-1,000°C. Five different values of heating rate have been applied β = 2, 5, 10, 15 and 20 K/min. The values of Ei and Ai have been determined for all recognised lumps of gaseous products. The method employed has also revealed its usefulness for the determination of kinetic parameters for municipal sludge, that possess an undefined content. An alternative route to combustion of sewage sludge is its gasification, which significantly increases the gaseous product (pyrolytic gas + syngas). Besides pyrolysis kinetics, gasification or combustion process kinetics have also been determined.

The thermal decomposition of t-alkyl N-arylcarbamates. I. The effect of ring substituents

1967 ◽  
Vol 45 (21) ◽  
pp. 2537-2546 ◽  
Author(s):  
M. P. Thorne
Keyword(s):  
Carbon Dioxide ◽  
Thermal Decomposition ◽  
Phenyl Ring ◽  
Diphenyl Ether ◽  
Decomposition Reaction ◽  
Aromatic Nucleus ◽  
Aryl Group ◽  
First Order ◽  
Cyclic Mechanism ◽  
Decomposition Increase

A series of t-butyl N-arylcarbamates in which the aryl group is a phenyl or a meta- or para-substituted phenyl ring has been prepared. Decomposition of these compounds in diphenyl ether at 177.5 °C has shown that the reaction is essentially first order, yielding carbon dioxide, isobutylene, and the corresponding amine. The rates of decomposition increase with increasing electronegativity of the substituent on the aromatic nucleus, and give a Hammett plot with a slope of 0.54. A cyclic mechanism is proposed for the decomposition reaction.

scholarly journals The effect of storage temperature and thermal processing on catechins, procyanidins and total flavonoid stability in commercially available cocoa powders

2015 ◽  
Vol 13 (1) ◽  
pp. 39-49 ◽  
Author(s):  
Jelena Mrmosanin ◽  
Aleksandra Pavlovic ◽  
Jovana Veljkovic ◽  
Snezana Mitic ◽  
Snezana Tosic ◽  
...  
Keyword(s):  
Room Temperature ◽  
Storage Temperature ◽  
Total Flavonoids ◽  
Order Kinetic ◽  
First Order ◽  
Temperature Range ◽  
Powder Samples ◽  
Order Kinetic Model ◽  
Calculated Activation ◽  
Thermal Stability Of

Storage stability of catechin, epicatechin, procyanidins B1-B4 and total flavonoids in cocoa powder samples was studied over the temperature range 4-35?C. Thermal stability of total flavonoids was studied over the temperature range 95-125?C. Total flavonoids concentration decreased as a function of time and the degradation was accelerated at higher temperatures: a half-life (t1/2) of total flavonoids was much shorter at room temperature than during cold storage. A first-order kinetic model fitted well to all the data. Temperature dependence of the degradation rate constants, described by the Arrhenius equation, was more pronounced during heating than during storage. In the temperature interval from 4?C to 35?C, the calculated activation energies (Ea) for catechin, epicatechin and procyanidins B1-B4 were 20.4 kJ/mol, 12.5 kJ/mol, 9.4 kJ/mol, 21.6 kJ/mol, 19.4 kJ/mol, 23.7 kJ/mol, respectively.

Thermal decomposition of magnesium sesquicarbide

1983 ◽  
Vol 48 (7) ◽  
pp. 1963-1968 ◽  
Author(s):  
Bohumil Hájek ◽  
Pavel Karen ◽  
Vlastimil Brožek
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Data ◽  
Arrhenius Equation ◽  
Kinetic Equations ◽  
Decomposition Reaction ◽  
Point Of View ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
Thermal Stability Of

The structure of Mg2C3 and the course of its decomposition were studied. The powder X-ray diffraction patterns were analyzed to obtain the lattice parameters for hexagonal Mg2C3, a = 743.4 ± 0.5 pm, c = 1 056.4 ± 1.6 pm. Thermal decomposition data were obtained for temperatures 670-740 °C and pressure 130 Pa; they could be fitted satisfactorily by kinetic equations for various processes, including the 1 st order decomposition reaction, and so the controlling phenomenon of the reaction cannot be deduced based on the kinetic data. The 1 st order rate constants and reaction halflives were evaluated for various temperatures and approximated by the Arrhenius equation to calculate the parameters AA = 1.97 . 1014 s-1, EA = 333 kJ mol-1. The conditions of synthesis of Mg2C3 are discussed from the point of view of the choice of a suitable hydrocarbon for the reaction with magnesium. The thermal stability of the sesquicarbide increases with increasing pressure; it could be formed from dicarbide and sustained even at a temperature of 1 450 °C by applying a pressure as high as 6 GPa.

scholarly journals Cure Kinetics of an Optical Polythiourethane with Amine Catalyst by IR Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Weiping Du ◽  
Guiming Zhang ◽  
Song Wang ◽  
Lianjiang Tan ◽  
Huifang Chen
Keyword(s):  
Reaction Rate ◽  
Activation Parameters ◽  
Cure Kinetics ◽  
Order Kinetic ◽  
Cure Reaction ◽  
First Order ◽  
Entropy Of Activation ◽  
Catalyst Content ◽  
Ir Analysis ◽  
Kinetics Of

An optical polythiourethane based on m-xylylene diisocyanate (XDI) and 4-mercaptomethyl-3,6-dithia-1,8-octanedithiol (BES) has been studied. Triethylamine was adopted as a catalyst, and the solid-state isothermal cure reaction was carried out using FTIR spectroscopy, in the temperature range of 75°C-105°C. The -NCO absorption band of XDI was used to monitor the conversion of diisocyanate into polythiourethane. The reaction rate enhanced with an increase in the content of the catalyst, and the gel time determined by swelling test was shorter for the system with higher catalyst content. Kinetic parameters were calculated from the infrared spectrum data, and the results showed that the curing reaction of polythiourethane accords with first-order kinetic characteristics. The activation parameters obtained from the evaluation of kinetic data were △H∗=97.22 kJ mol−1, △S∗=−6.77 J K−1 mol−1, and Ea=100.23 kJ mol−1. The observed negative entropy of activation value supported the formation of a transition state in the cure reaction.

Effect of Organotin on the Thermal Stability of Poly(Vinyl Chloride)

2012 ◽  
Vol 550-553 ◽  
pp. 838-842 ◽  
Author(s):  
Feng Wei ◽  
Yi Heng Lu ◽  
Wei Long Liu
Keyword(s):  
Decomposition Reaction ◽  
Decomposition Temperature ◽  
Initial Reaction ◽  
Scanning Method ◽  
First Order ◽  
Third Phase ◽  
Poly Vinyl Chloride ◽  
Thermal Degradation Behavior ◽  
Three Stages ◽  
Thermal Stability Of

The thermal degradation behavior of PVC stabilized by the organotin were investigated by means of the thermogravimetric analysis and non-isothermal multiple scanning method. The results indicate that the lowest decomposition temperature is greater than 210°C in the conversion rate of 5%. The decomposition process occurred in three stages. The results calculated by Kissinger, Ozawa, Starink and Friedman methods show that the average apparent activation energy in first, second and third phase is 98.46kJ/mol, 111.24kJ/mol and 243.23kJ/mol respectively. In the initial reaction (α<10%), the decomposition reaction is controlled by the first order (F1) mechanism, with a half-life of 4.92h at 180°C.

scholarly journals Thermostability of the visual color and anthocyanins from Rio-Grande-Cherry (Eugenia involucrata DC)

2020 ◽  
Vol 23 ◽  
Author(s):  
Lauren Menegon de Oliveira ◽  
Francine Antelo
Keyword(s):  
Rio Grande ◽  
Color Difference ◽  
Order Kinetic ◽  
First Order ◽  
Color Parameters ◽  
Visual Color ◽  
Order Kinetic Model ◽  
Degradation Reaction ◽  
Thermal Stability Of ◽  
Total Color Difference

Abstract The extract of Rio-Grande-Cherry (Eugenia involucrata DC), pure and with stevia addition (0.75% and 1.5%) and sucrose addition (20% and 40%), was subjected to heat treatment at 10 °C, 25 °C and between 50 °C and 90 °C. Anthocyanins and the color parameters C* and TCD (total color difference) followed first-order reaction kinetics while h° followed a zero order kinetic model, under all conditions. The addition of sweeteners, through the reduction of water activity, influenced the thermal stability of the anthocyanins and of the color parameters C*, h° and TCD was the most pronounced effect in the latter. The lower the temperatures, the most relevant was the effect of the sweeteners on increasing half-life. Thermodynamically, the degradation reaction of anthocyanins was defined as endothermic, as well as non-spontaneous and transition state of the molecules more structurally organized than the reactants.

Kinetics and mechanism of the thermal decomposition of the thiosulphatopentaamminecobalt(III) ion in dilute aqueous acid

1986 ◽  
Vol 64 (2) ◽  
pp. 311-313
Author(s):  
Anthony Martin Newton
Keyword(s):  
Thermal Decomposition ◽  
Acetic Acid ◽  
Sodium Acetate ◽  
Major Product ◽  
Order Kinetic ◽  
Sodium Acetate Buffer ◽  
Reaction Products ◽  
First Order ◽  
Aqueous Acid ◽  
Reactive Complex

In acetic acid – sodium acetate buffer of pH 5.6 (25 °C) the Co(NH3)5S2O3+ ion undergoes redox decomposition rather than aquation. First-order kinetic are observed and the reaction products Co2+, NH3, and S4O62− are due to internal reduction of Co(III) by coordinated S2O32−. In dilute perchloric acid of pH < 4 the rate is retarded, first-order plots are not linear, and S4O62− is not a major product of the reaction. It is proposed that, in dilute HClO4, protonation of Co(NH3)5S2O3+ depletes the concentration of the reactive complex and that decomposition of coordinated HS2O3− occurs. Conversion of O-bonded S2O32− to S-bonded S2O32− in the reactive complex is also considered.

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