Mechanism of Formation of Zinc Dimethyldithiocarbamate (ZnDMDC) in Tetramethylthiuram Disulfide (TMTD) Vulcanization

1956 ◽  
Vol 29 (3) ◽  
pp. 944-945 ◽  
Author(s):  
David Craig
Keyword(s):  
Zinc Oxide ◽  
Mechanism Of Formation ◽  
Tetramethylthiuram Disulfide ◽  
Rate Law ◽  
First Order ◽  
Order Rate ◽  
Excess Zinc

Abstract Scheele and Bielstein recently have commented at length on the copolymerization (CP) theory of vulcanization which we proposed. They find the theory untenable with respect to TMTD vulcanization as well as with that using equivalent amounts of tetramethylthiuram monosulfide (TMTM) and sulfur. They feel that our presentation lacked in clarity and, therefore, that they did not understand it fully. Scheele and coworkers report that 66 per cent of the TMTD, or of the mixture of equivalent amounts of TMTM and sulfur, reacts to form ZnDMDC according to the first-order rate law during vulcanization in the presence of excess zinc oxide. This finding is a notable contribution. In particular, it suggests the possibility of sulfur-oxygen interchange as a feature of the overall reaction, which we may write:

1H-DNMR-Untersuchungen zur inter- und intramolekularen Ligandenmobilität im System Co(II)/[18]Krone-6 / 1H DNMR Studies on the Inter- and Intramolecular Ligand Mobility in the System Co(II)/[18]crown-6

1984 ◽  
Vol 39 (1) ◽  
pp. 69-73 ◽  
Author(s):  
Franz L. Dickert ◽  
Walter Gumbrecht
Keyword(s):  
Crown Ether ◽  
Intermediate Product ◽  
Outer Sphere ◽  
Second Order ◽  
Ligand Concentration ◽  
Rate Law ◽  
First Order ◽  
Order Rate

The crown ether exchange could be studied in non-coordinating solvents by using the hy­drophobic complex [Co([18]crown-6)] + + . Appreciable outer-sphere association between complex and ligand (K°(50 °C) = 12 ± 0.5 M-1) occurs. This changes the second order rate law to first order (kmono(50 °C) = 7900 ± 500 s_1) with increasing ligand concentration. In the complex mer-[Co([18]crown-6)(CH3OH)3]+ + the stereochemical rearrangement of the uncoordinated part of the crown ether follows an intramolecular pathway via the complex [Co([18]crown-6)]++ as an intermediate product.

Die Kinetik des Zerfalls von tert. Butylperoxypivalat bei hohen Drücken und Temperaturen / The Kinetics of the Decomposition of tert.Butylperoxypivalate up to High Pressures and Temperatures

1981 ◽  
Vol 36 (12) ◽  
pp. 1371-1377 ◽  
Author(s):  
M. Buback ◽  
H. Lendle
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
High Pressures ◽  
Activation Volume ◽  
Rate Law ◽  
First Order ◽  
Order Rate ◽  
High Pressures And Temperatures ◽  
Kinetics Of

AbstractThe decomposition of tert. butylperoxypivalate dissolved in n-heptane has been measured ir-spectroscopically in optical high-pressure cells up to 2000 bar at temperatures between 65 °C and 105 °C. The reaction follows a first order rate law with an activation energy Ea = 122.3 ±3.0 kJ · mol-1 and an activation volume ⊿V≠ = 1.6 ± 1.0 cm3 mol-1 .

Revisiting the mechanism of β-O-4 bond cleavage during acidolysis of lignin. Part 1: Kinetics of the formation of enol ether from non-phenolic C6-C2 type model compounds

Holzforschung ◽  
2008 ◽  
Vol 62 (2) ◽  
pp. 164-168 ◽  
Author(s):  
Tomoya Yokoyama ◽  
Yuji Matsumoto
Keyword(s):  
Rate Constant ◽  
Bond Cleavage ◽  
Formation Rate ◽  
Type Model ◽  
Enol Ether ◽  
Rate Law ◽  
Lignin Model Compound ◽  
First Order ◽  
Order Rate ◽  
Pseudo First Order

Abstract The reaction route of a dimeric non-phenolic C6-C2 type lignin model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)ethanol (VIII), was kinetically examined under acidolysis conditions (0.2 mol l-1 HBr in 82% aqueous 1,4-dioxane at 85°C). The disappearance of (VIII) followed the pseudo-first-order rate law, and the rate constant k (VIII) was 0.00854. In the course of the reactions, the following compounds were produced quantitatively at any time: an enol ether, 1-(2-methoxyphenoxy)-2-(3,4-dimethoxyphenyl)ethylene (IX), 2-methoxyphenol (X), and a Hibbert's ketone, 3,4-dimethoxyphenylacetaldehyde (XI). The substances (X) and (XI) are the result of the β-O-4 bond cleavage and their amounts were always equal during the whole reaction. When (IX) was subjected to the acidolysis under the identical conditions, its disappearance followed the pseudo-first-order rate law, and the rate constant k (IX) was 0.00825. Furthermore, (VIII) was not observed at all, and (X) was produced quantitatively at any time. Based on these results, the formation rate of (IX) during the acidolysis of (VIII) is expressed by the equation: d[(IX)]/dt=A·k (VIII)[(VIII)]-k (IX)[(IX)], where A is the proportion of (VIII) that converted into (IX) when (VIII) degraded. It was confirmed by solving this differential equation that the formation and disappearance of (IX) is best simulated when A was assumed to be 1.00. Therefore, it was proven in this paper for the first time that (VIII) primarily converts into (IX), and subsequently the β-O-4 bond cleavage occurs and (X) and (XI) are yielded.

Thallic Ion Oxidation of Styrene: Kinetics of Decomposition of the Oxythallation Adduct C6H5—CH(OCH3)—CH2Tl(OAc)2

1974 ◽  
Vol 52 (15) ◽  
pp. 2667-2672 ◽  
Author(s):  
Louise Nadon ◽  
Miklos Zador
Keyword(s):  
Kinetic Parameters ◽  
Reactive Species ◽  
Rate Law ◽  
First Order ◽  
Order Rate ◽  
Rate Determining Step ◽  
Kinetics Of Decomposition ◽  
Low Concentrations ◽  
Kinetics Of

The kinetics of decomposition of the organo-thallic adduct formed in methanol between styrene and Tl(OAc)3, (C6H5—CH(OCH3)—CH2—Tl(OAc)2) has been studied in a water–methanol solvent. The reaction follows a first order rate law. The organo-thallic compound, RTl(OAc)2, is shown to be dissociated at low concentrations yielding two reactive species, RTlOH+ and RTl2+. The influence of acidity on the rate of decomposition shows that RTl2+ is much more reactive than RTiOH+. The kinetic parameters have been determined. The implication of the results on the rate-determining step of Tl(III) oxidation of styrene is discussed.

scholarly journals BENTAZON PREEMERGENCE ACTIVITY ON VELVETLEAF (Abutilon theophrasti MEDIC) AND PERSISTENCE IN SOUTHWESTERN ONTARIO SOILS

1983 ◽  
Vol 63 (4) ◽  
pp. 1015-1022 ◽  
Author(s):  
J. D. GAYNOR ◽  
A. S. HAMILL
Keyword(s):  
Laboratory Experiments ◽  
Soil Layer ◽  
Abutilon Theophrasti ◽  
Laboratory Studies ◽  
Surface Layers ◽  
Rate Law ◽  
First Order ◽  
Order Rate ◽  
Weed Seeds

Field and laboratory studies have demonstrated that bentazon (3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide) can effectively control velvetleaf (Abutilon theophrasti Medic) before the weed emerges from the soil. Laboratory experiments showed that the effectiveness of the bentazon depended upon its concentration in the soil and on the weed seeds being in or above the soil layer containing the herbicide. Experiments in the field relating velvetleaf control to bentazon residues in soil showed that velvetleaf can be controlled in southwestern Ontario when bentazon residues in the surface layers of soil exceed 0.2 kg/ha. Bentazon was rapidly degraded in two soils in southwestern Ontario with residues of less than 0.02 kg/ha 40 days after application. Degradation was closely approximated by first order rate law. Thus, an application of 1.0 kg/ha of bentazon should have residual preemergence activity against velvetleaf for 3–12 days after application.Key words: Degradation, residues, herbicide

Die Kinetik des Zerfalls von Ditertiärbutylperoxid bei hohen Drücken und Temperaturen / The Kinetic of the Decomposition of Di-tertiary-butyl-peroxide up to High Pressures and Temperatures

1979 ◽  
Vol 34 (12) ◽  
pp. 1482-1488 ◽  
Author(s):  
M. Buback ◽  
H. Lendle
Keyword(s):  
Activation Energy ◽  
High Pressures ◽  
Activation Volume ◽  
Tertiary Butyl ◽  
Rate Law ◽  
First Order ◽  
Order Rate ◽  
Peroxide Decomposition ◽  
Butyl Peroxide ◽  
High Pressures And Temperatures

AbstractThe decomposition of di-tertiary-butyl-peroxide dissolved in n-heptane has been measured ir-spectroscopically up to pressures of 2300 bar at temperatures between 140 °C and 200 °C. The reaction follows a first order rate law with an activation energy Ea = 151.4 ± 1.6 kJ mol-1 and an activation volume ΔV ǂ = 10.1 ± 1.1 cm3 mol-1. The effectivity of the peroxide decomposition is discussed.

Chemical stabilization of recoil 56Mn in MnSO4-KClO4 mixed crystals following (n, γ) process

2005 ◽  
Vol 93 (9-10) ◽  
Author(s):  
Shuddhodan P. Mishra ◽  
M. Vijaya
Keyword(s):  
Mixed Crystals ◽  
Chemical Stabilization ◽  
Rate Law ◽  
First Order ◽  
Order Rate

SummaryStabilization of recoilThe rate of annealing was found to increase while the extent of annealing decreased. The recoil re-entry process obeys first order rate law and the energies of activation for the system (MnSO

A kinetic standard for precise calibration of spectrophotometer cell temperature.

1981 ◽  
Vol 27 (5) ◽  
pp. 753-755 ◽  
Author(s):  
P A Adams ◽  
M C Berman
Keyword(s):  
Temperature Dependence ◽  
Rate Constants ◽  
Cell Temperature ◽  
First Order ◽  
Order Rate ◽  
Acid Catalyzed ◽  
Pseudo First Order ◽  
Hydrolysis Of

Abstract We describe a simple, highly reproducible kinetic technique for precisely measuring temperature in spectrophotometric systems having reaction cells that are inaccessible to conventional temperature probes. The method is based on the temperature dependence of pseudo-first-order rate constants for the acid-catalyzed hydrolysis of N-o-tolyl-D-glucosylamine. Temperatures of reaction cuvette contents are measured with a precision of +/- 0.05 degrees C (1 SD).

PLATELET AGGREGATION DOES NOT CONFORM TO SIMPLE PARTICLE COLLISION THEORY

1987 ◽  
Author(s):  
Moideen P Jamaluddin
Keyword(s):  
Platelet Aggregation ◽  
Rate Equation ◽  
Rate Constants ◽  
Kinetic Scheme ◽  
Order Type ◽  
Second Order ◽  
Particle Collision ◽  
Collision Theory ◽  
Rate Law ◽  
First Order

Platelet aggregation kinetics, according to the particle collision theory, generally assumed to apply, ought to conform to a second order type of rate law. But published data on the time-course of ADP-induced single platelet recruitment into aggregates were found not to do so and to lead to abnormal second order rate constants much larger than even their theoretical upper bounds. The data were, instead, found to fit a first order type of rate law rather well with rate constants in the range of 0.04 - 0.27 s-1. These results were confirmed in our laboratory employing gelfiltered calf platelets. Thus a mechanism much more complex than hithertofore recognized, is operative. The following kinetic scheme was formulated on the basis of information gleaned from the literature.where P is the nonaggregable, discoid platelet, A the agonist, P* an aggregable platelet form with membranous protrusions, and P** another aggregable platelet form with pseudopods. Taking into account the relative magnitudes of the k*s and assuming aggregation to be driven by hydrophobic interaction between complementary surfaces of P* and P** species, a rate equation was derived for aggregation. The kinetic scheme and the rate equation could account for the apparent first order rate law and other empirical observations in the literature.

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