Halogenation with N-haloamines in strong acids. II. Kinetics and rate constants

1970 ◽  
Vol 48 (4) ◽  
pp. 554-560 ◽  
Author(s):  
J. Spanswick ◽  
K. U. Ingold
Keyword(s):  
Rate Constant ◽  
Decanoic Acid ◽  
Propagation Rate ◽  
The Self ◽  
Radical Chain ◽  
Rate Of Reaction ◽  
Propagation Rate Constant ◽  
Strong Acids ◽  
Kinetics Of ◽  
Rate Controlling Step

The kinetics of the radical chain chlorination of decanoic acid by N-chlorodimethylamine and N-chloropiperidine in 2 and 4 M H2SO4 in acetic acid have been examined at 30°. The rate of reaction is proportional to the decanoic acid concentration and to the square root of the rate of chain initiation. The rate controlling step for propagation involves the attack of an aminium radical on decanoic acid, and termination involves the self-reaction of two aminium radicals. The latter reaction may involve the prior, rapid deprotonation of one or both radicals. The propagation rate constant has been estimated to be in the range 7 × 102 to 1 × 104 M−1 s−1 and the termination rate constant to be in the range 6 × 106 to 5 × 107 M−1 s−1.

Synthesis and Polymerization Kinetics of PMMA in Imidazolium Ionic Liquids

2013 ◽  
Vol 423-426 ◽  
pp. 528-531
Author(s):  
Pei Wang ◽  
Yuan Liu ◽  
Wen Su ◽  
Lian Liu
Keyword(s):  
Molecular Weight ◽  
Rate Constant ◽  
Average Molecular Weight ◽  
Propagation Rate ◽  
Polymerization Kinetics ◽  
Growth Rate Constant ◽  
Weight Average Molecular Weight ◽  
Propagation Rate Constant ◽  
Kinetics Of ◽  
Chain Propagation Rate

Polymerization of high molecular weight PMMA was achieved in [BMIM]PF4at reaction temperature 60oC, 65°C and 70 °C, reaction time 60min. The data including the yield, molecular weight and molecular weight distribution of PMMA were analysized. The results showed that the weight average molecular weight of PMMA in [BMIM]PF4is up to 275867, respectively 4 and 7 times of molecular weight in cyclohexane and toluene. Secondly, the polymerization kinetics of PMMA in [BMIM]PF4were tested, the apparent chain propagation rate constant of PMMA are 0.93×104,1.11 ×104and 14.1×104in 60 °C, 65°C and 70 °C. Compared with the growth rate constant in toluene, the polymerization rate constant PMMA in the ionic liquid increased by 4~7 times.

Synthesis and Polymerization Kinetics of PMMA in [BMIM]BF6 Imidazolium Ionic Liquids

2013 ◽  
Vol 395-396 ◽  
pp. 411-414 ◽  
Author(s):  
Pei Wang ◽  
Yuan Liu ◽  
Wen Su ◽  
Lian Liu
Keyword(s):  
Molecular Weight ◽  
Rate Constant ◽  
Average Molecular Weight ◽  
Propagation Rate ◽  
Polymerization Kinetics ◽  
Growth Rate Constant ◽  
Weight Average Molecular Weight ◽  
Propagation Rate Constant ◽  
Kinetics Of ◽  
Chain Propagation Rate

Polymerization of high molecular weight PMMA was achieved in [BMIPF6by contrasted in cyclohexane, toluene solvent at reaction temperature 60 C, 65C and 70 C, reaction time 60min. The data including the yield, molecular weight and molecular weight distribution of PMMA were analysized in 3 kind of solvent. The results showed that the weight average molecular weight of PMMA in [BMIPF6is up to 730000, respectively 7 and 10 times of molecular weight in cyclohexane and toluene. Secondly, the polymerization kinetics of PMMA in [BMIPF6were tested, the apparent chain propagation rate constant of PMMA are 10.7×10412.9 ×104and 19.9×104in 60 C, 65C and 70 C. Compared with the growth rate constant in toluene, the polymerization rate constant PMMA in the ionic liquid increased by 5~10 times.

Emulsion polymerization of styrene

1959 ◽  
Vol 253 (1274) ◽  
pp. 331-348 ◽  
Keyword(s):  
Emulsion Polymerization ◽  
Rate Constant ◽  
Propagation Rate ◽  
Critical Examination ◽  
Reaction Site ◽  
Latex Particles ◽  
Rate Of Reaction ◽  
Propagation Rate Constant

A critical examination of the emulsion polymerization of styrene has been carried out with a simplified emulsion recipe. In particular, attention has been paid to precise methods of measuring the rate of reaction, the number of latex particles and the concentration of monomer at the reaction site. On the basis of these measurements the propagation rate constant has been evaluated by means of the expression of the Smith—Ewart theory of polymerization in emulsion. The value obtained is very little different from that found in bulk polymerizations in styrene.

scholarly journals Kinetics of thiamin cleavage by sulphite

1969 ◽  
Vol 113 (4) ◽  
pp. 611-615 ◽  
Author(s):  
J. Leichter ◽  
M. A. Joslyn
Keyword(s):  
Aqueous Solutions ◽  
Rate Constant ◽  
Sulphur Dioxide ◽  
First Order ◽  
Ph Values ◽  
Rate Of Reaction ◽  
Kinetics Of

Results are presented on the rate of thiamin cleavage by sulphite in aqueous solutions as affected by temperature (20–70°), pH(2·5–7·0), and variation of the concentration of either thiamin (1–20μm) or sulphite (10–5000μm as sulphur dioxide). Plots of the logarithm of percentage of residual thiamin against time were found to be linear and cleavage thus was first-order with respect to thiamin. At pH5 the rate was also found to be proportional to the sulphite concentration. In the pH region 2·5–7·0 at 25° the rate constant was 50m−1hr.−1 at pH5·5–6·0, and decreased at higher or lower pH values. The rate of reaction increased between 20° and 70°, indicating a heat of activation of 13·6kcal./mole.

scholarly journals Estimation of activation parameters for the propagation rate constant of styrene

1996 ◽  
Vol 34 (12) ◽  
pp. 2473-2479 ◽  
Author(s):  
Bart G. Manders ◽  
Gr�gory Chambard ◽  
Wieb J. Kingma ◽  
Bert Klumperman ◽  
Alex M. Van Herk ◽  
...  
Keyword(s):  
Rate Constant ◽  
Activation Parameters ◽  
Propagation Rate ◽  
Propagation Rate Constant

scholarly journals Kinetic and spectrophotometric studies on the renaturation of deoxyribonucleic acid

1968 ◽  
Vol 109 (4) ◽  
pp. 543-557 ◽  
Author(s):  
K. J. Thrower ◽  
A. R. Peacocke
Keyword(s):  
Ionic Strength ◽  
Rate Constant ◽  
Base Pairs ◽  
Phage Dna ◽  
Dna Strands ◽  
Entropy Of Activation ◽  
T7 Phage ◽  
Kinetics Of ◽  
Rate Controlling Step ◽  
Adenine Thymine

The kinetics of the renaturation of Escherichia coli DNA in 0·4–1·0m-sodium chloride at temperatures from 60° to 90° have been studied. The extent of renaturation was a maximum at 65° to 75° and increased with ionic strength, and the rate constant increased with both ionic strength and temperature. The energy and entropy of activation of renaturation were calculated to be 6–7kcal.mole−1 and −40cal.deg.−1mole−1 respectively. It has been shown that renaturation is a second-order process for 5hr. under most conditions. The results are consistent with a reaction in which the rate-controlling step is the diffusion together of two separated complementary DNA strands and the formation of a nucleus of base pairs between them. The kinetics of the renaturation of T7-phage DNA and Bordetella pertussis DNA have also been studied, and their rates of renaturation related quantitatively to the relative heterogeneity of the DNA samples. By analysis of the spectra of DNA at different stages during renaturation it was shown that initially the renatured DNA was rich in guanine–cytosine base pairs and non-random in base sequence, but that, as equilibrium was approached, the renatured DNA gradually resembled native DNA more closely. The rate constant for the renaturation of guanine–cytosine base pairs was slightly higher than for adenine–thymine base pairs.

scholarly journals An Estimation of the Propagation Rate Constant for the Radiation-Induced Polymerization of Gaseous Isobutene

1968 ◽  
Vol 41 (7) ◽  
pp. 1737-1737 ◽  
Author(s):  
Yasuyuki Noro ◽  
Kenji Fueki ◽  
Zen-ichiro Kuri
Keyword(s):  
Rate Constant ◽  
Propagation Rate ◽  
Radiation Induced ◽  
Propagation Rate Constant

Kinetics of the reaction H + C2H6 → H2 + C2H5 in the temperature region of 1000 K

1984 ◽  
Vol 62 (1) ◽  
pp. 86-91 ◽  
Author(s):  
J.-R. Cao ◽  
M. H. Back
Keyword(s):  
Equilibrium Constant ◽  
Rate Constant ◽  
Temperature Region ◽  
Recent Measurement ◽  
Hydrogen Atoms ◽  
Elementary Reactions ◽  
Temperature Range ◽  
Hydrogen Molecules ◽  
Kinetics Of ◽  
Rate Controlling Step

A system for the measurement of rate constants for elementary reactions of hydrogen atoms in the temperature region of 1000 K is described. The concentration of hydrogen atoms is controlled by the equilibrium constant for dissociation of hydrogen molecules. The kinetics of the rate of conversion of ethane to ethylene in this system has been studied over the temperature range 876–1016 K. The results show that the rate-controlling step is[Formula: see text]and the value obtained for the rate constant is[Formula: see text](R = 1.987 cal mol−1 deg−1). This value is compared with values obtained from other methods over the temperature range 300–1400 K. Combination with a recent measurement of the rate constant for the reverse reaction yields an experimental value for the equilibrium constant for the reaction.

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