THE KINETICS OF THE REACTION OF ORGANIC ISOTHIOCYANATES WITH 1-OCTANOL IN o-DICHLOROBENZENE

1962 ◽  
Vol 40 (12) ◽  
pp. 2369-2375 ◽  
Author(s):  
Yoshio Iwakura ◽  
Hisao Okada
Keyword(s):  
Reaction Mechanism ◽  
Rate Constants ◽  
Catalytic Effect ◽  
Relative Rate ◽  
Slow Step ◽  
Dibutyltin Dilaurate ◽  
Kcal Mole ◽  
Large Excess ◽  
First Order ◽  
Kinetics Of

The kinetics of the reaction of organic isothiocyanates with a large excess of 1-octanol in o-dichlorobenzene was examined at 90–140°. The rate of the reaction was first order with respect to the concentration of isothiocyanate, but the apparent second-order rate constants calculated varied according to the initial 1-octanol concentration. These facts can be explained by a reaction mechanism involving two molecules of 1-octanol in the transition state for the slow step of the reaction. The relative rate of the reaction of isothiocyanates with 1-octanol at 120° decreased in the order of benzyl, phenyl, allyl, ethyl, n-butyl, n-hexyl, isobutyl, and cyclohexyl isothiocyanate. The apparent energies of activation and log A were obtained as 13.5–16.5 kcal/mole and 4.65–6.46 (A in liter/mole min), respectively. Tributylamine had a slight catalytic effect, but dibutyltin dilaurate and ferric acetylacetonate had a strong catalytic action in these reactions.

The kinetics of hydration of tricalcium silicate

1970 ◽  
Vol 48 (21) ◽  
pp. 3291-3299 ◽  
Author(s):  
K. G. McCurdy ◽  
B. P. Erno
Keyword(s):  
Reaction Mechanism ◽  
Intermediate Product ◽  
Activation Energies ◽  
Tricalcium Silicate ◽  
Rate Data ◽  
Large Excess ◽  
First Order ◽  
Kinetics Of ◽  
Subsequent Decomposition

An investigation has been made of the kinetics of hydration of tricalcium silicate at several temperatures in a large excess of water in the presence of various added ions. The rate data have been interpreted by a reaction mechanism which involves: (a) the first order hydration of tricalcium silicate to form an intermediate product, 1.5CaO•SiO2, which can react by two pathways, (b) the direct first order decomposition of intermediate, 1.5CaO•SiO2, to form lime and silica or (b′) complexing of intermediate with silica and subsequent decomposition to form lime and silica. This reaction mechanism predicts the rate of production of base during the hydration. The effect of various added ions is interpreted in terms of the proposed mechanism.Rate constants and activation energies for the various steps in the proposed mechanism are reported.

Vulcanization of Elastomers. 40. Vulcanization of Natural Rubber and Synthetic Rubber with Sulfur in Presence of Sulfenamides. III

1965 ◽  
Vol 38 (1) ◽  
pp. 189-203 ◽  
Author(s):  
W. Scheele ◽  
J. Helberg
Keyword(s):  
Activation Energy ◽  
Reaction Mechanism ◽  
Natural Rubber ◽  
Rate Constants ◽  
Sulfur Concentration ◽  
Kcal Mole ◽  
Synthetic Rubber ◽  
Chemical Constitution ◽  
Induction Times ◽  
Kinetics Of

Abstract Vulcanization of natural rubber with sulfur was studied in presence of six sulfenamides, to determine the effect of the chemical constitution of the sulfenamide on sulfur decrease and on crosslinking. The results can be condensed as follows: (1) The kinetics of sulfur disappearance is in every respect qualitatively independent of the chemical constitution of the sulfenamide. (2) For the sulfenamides investigated, the smallest and largest rate constants for sulfur decrease differed only by a factor of two. (3) Greater differences are encountered in the induction times for sulfur decrease and for crosslinking. The latter are notably longer than those for sulfur disappearance. (4) The same activation energy, 23 kcal/mole, is derived from the temperature dependence of the induction times for all the sulfenamides. (5) The dissociation of sulfenamides in solution and their reaction with mercaptobenzothiazole were investigated further. The results provide the basis for a proposed reaction mechanism, which is presented in detail and can account for a number of the features typical of sulfenamide-accelerated vulcanization. (6) The drop in sulfur concentration goes at practically the same rate, if one introduces, instead of N, N-dicyclohexyl-2-benzothiazolesulfenamide, the corresponding ammonium mercaptide in equimolar concentration.

Kinetics and mechanisms of the thermal decomposition of propane II. The reaction inhibited by nitric oxide

1962 ◽  
Vol 270 (1341) ◽  
pp. 254-266 ◽  
Keyword(s):  
Nitric Oxide ◽  
Volume Ratio ◽  
Inflexion Point ◽  
Kcal Mole ◽  
Large Excess ◽  
First Order ◽  
Partial Pressures ◽  
Pressure Time ◽  
Initiation Reaction ◽  
Kinetics Of

The kinetics of the pyrolysis of propane inhibited by nitric oxide were investigated from 640 to 560 °C and at partial pressures of propane from 25 to 550 mm Hg. The pressure-time curves were found to be S-shaped, and the induction period was lengthened considerably as the propane pressure was lowered. Complete inhibition by nitric oxide was obtained with 10 to 12% nitric oxide. The initial rates were found to be proportional to the 3/2 power of the pressure over most of the temperature range, and to a slightly lower power at the highest temperatures. The orders of reaction corresponding to the inflexion point are close to unity at the highest temperatures, and increase steadily as the temperature is lowered. The activation energy calculated from the inflexion rates in the first-order region was 69.4 kcal/ mole. The rates decreased with an increase in the surface to volume ratio. The addition of a large excess of carbon dioxide had no effect on the fully inhibited rates. The results are shown to be consistent with a mechanism in which the initiation reaction involves the abstraction of a hydrogen atom from propane by nitric oxide, and in which the termination reaction is between HNO and a propyl radical.

Kinetics of reactions involving CN emission. II. The reaction between oxygen atoms and cyanogen

1965 ◽  
Vol 288 (1413) ◽  
pp. 275-291 ◽  
Keyword(s):  
Flow System ◽  
Relative Rate ◽  
Initial Attack ◽  
Kcal Mole ◽  
Exponential Factor ◽  
First Order ◽  
Relative Rate Constants ◽  
Kinetics Of ◽  
O 10 ◽  
Oxygen Atoms

The reaction between oxygen atoms and cyanogen has been studied in a flow system at temperatures up to 400 °C in the pressure range 1.0 to 5.0 mmHg. This reaction is first order in both reactants, and has an activation energy of 11.0 ± 2.0 kcal/mole; this is associated with the initial attack of an oxygen atom on cyanogen for which the exponential factor is close to 4 x 10 13 cm 3 mole -1 s -1 . It has not been possible to choose between mechanisms in which the initial steps are O + C 2 N 2 = NCO + CN (6) and O + NCO = NO + CO, (7) or O + C 2 N 2 = NCN + CO (8) and O + NCN = NO + CN. (9) Subsequent reactions include CN + NO = CO + N 2 , (11) O + CN = N + CO. (12) In the presence of molecular oxygen reactions (10) and (7) become important CN + O 2 = NCO + O. (10) Strong CN emission accompanying the reaction is shown to be largely due to the reaction O+O+CN = O 2 + CN*. (20) Quenching of this emission by various additives is associated with their reaction with CN for which relative rate constants are deduced.

THE KINETICS OF THE TERTIARY-AMINE-CATALYZED REACTION OF ORGANIC ISOCYANATES WITH THIOLS

1960 ◽  
Vol 38 (12) ◽  
pp. 2418-2424 ◽  
Author(s):  
Yoshio Iwakura ◽  
Hisao Okada
Keyword(s):  
Reaction Mechanism ◽  
Tertiary Amine ◽  
Relative Rate ◽  
Catalytic Action ◽  
Tertiary Amines ◽  
First Order ◽  
Kinetics Of

The kinetics of the reactions of isocyanates with thiols in the presence of tertiary amines were examined. The rate of the reaction was of the first order with respect to the concentration of isocyanate, thiol, and tertiary amine. The catalytic action of tertiary amines decreased in the order of triethylenediamine, triethylamine, diethylcyclohexylamine, tributylamine, N-methylmorpholine, pyridine, and quinoline. The relative rate of the reaction of phenylisocyanate with thiols decreased in the order of phenylmethanethiol, 1,4-butanedithiol, 1-butanethiol, 1-dodecanethiol, and thiophenol. The reaction took place more smoothly in strong ionizing solvents. These facts can be explained by the reaction mechanism indicated by the equations [6] to [8].

Vulcanization of Elastomers. 24. The Effect of Fillers on the Course of Vulcanization Reactions. I

1960 ◽  
Vol 33 (2) ◽  
pp. 326-334
Author(s):  
Walter Scheele ◽  
Günter Mau ◽  
Gregor Kemme
Keyword(s):  
Chemical Reactions ◽  
Rate Constants ◽  
Chemical Mechanism ◽  
Rubber Compound ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Qualitative Effect ◽  
Kinetics Of ◽  
Limiting Value

Abstract The effect of Aerosil on the chemical reactions and the kinetics observed in thiuram vulcanizations was subjected to closer scrutiny. Results now available show: 1. Aerosil does not alter the chemical mechanism of thiuram vulcanizations. It also has no qualitative effect on the kinetics of the various reactions involved. Thiuram disappearance and dithiocarbamate formation over by far the greatest range of conversions are first order reactions. Nevertheless, the limiting value of dithiocarbamate formation is somewhat higher than in the absence of Aerosil. 2. Quantitatively speaking, essential differences are involved. The rate constants for both thiuram loss and dithiocarbamate formation rise considerably when Aerosil is used; in both cases there is a dependence on the Aerosil content of the rubber compound. Yet the activation energies of thiuram disappearance and dithiocarbamate formation are practically the same as in Aerosil-free thiuram vulcanizations, amounting to about 21 kcal/mole. 3. Measurements of the limiting equilibrium swelling reveal that adding Aerosil does not result in additional crosslinking, so that in thiuram vulcanizations the catalytic action displayed by silica gel is the outstanding feature.

Submerged upflow biotower operation and computer simulation

1994 ◽  
Vol 30 (11) ◽  
pp. 143-146
Author(s):  
Ronald D. Neufeld ◽  
Christopher A. Badali ◽  
Dennis Powers ◽  
Christopher Carson
Keyword(s):  
Computer Simulation ◽  
Benzoic Acid ◽  
Computer Model ◽  
Rate Constants ◽  
Batch Mode ◽  
Operational Conditions ◽  
First Order ◽  
Low Concentrations ◽  
Biological Transformation ◽  
Kinetics Of

A two step operation is proposed for the biodegradation of low concentrations (< 10 mg/L) of BETX substances in an up flow submerged biotower configuration. Step 1 involves growth of a lush biofilm using benzoic acid in a batch mode. Step 2 involves a longer term biological transformation of BETX. Kinetics of biotransformations are modeled using first order assumptions, with rate constants being a function of benzoic acid dosages used in Step 1. A calibrated computer model is developed and presented to predict the degree of transformation and biomass level throughout the tower under a variety of inlet and design operational conditions.

Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

1960 ◽  
Vol 33 (2) ◽  
pp. 335-341
Author(s):  
Walter Scheele ◽  
Karl-Heinz Hillmer
Keyword(s):  
Activation Energy ◽  
Physical Properties ◽  
Chemical Kinetics ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Limiting Value ◽  
Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

Kinetics of the successive chlorination of 1,2-dichloroethane in the liquid phase

1969 ◽  
Vol 22 (6) ◽  
pp. 1177 ◽  
Author(s):  
DS Caines ◽  
RB Paton ◽  
DA Williams ◽  
PR Wilkinson
Keyword(s):  
Liquid Phase ◽  
Rate Constants ◽  
Relative Rate ◽  
Stirred Tank ◽  
Continuous Stirred Tank Reactor ◽  
Alternative Pathways ◽  
Tank Reactor ◽  
Relative Rate Constants ◽  
Continuous Stirred Tank ◽  
Kinetics Of

Liquid 1,2-dichloroethane has been chlorinated by dissolved chlorine to a succession of chloroethanes up to the ultimate hexachloroethane. The results of both batch and continuous stirred tank reactor systems have been analysed by computer techniques to give a set of relative rate constants from which one can predict the product composition for a given chlorine uptake, the aim in this work being to optimize the production of tetrachloroethanes. An unusual feature of the kinetics is that 1,1,1,2- and 1,1,2,2-tetrachloroethanes provide alternative pathways between 1,1,2-trichloroethane and pentachloroethane.

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