Kinetic Analysis for the Multistep Profiles of Organic Reactions: Significance of the Conformational Entropy on the Rate Constants of the Claisen Rearrangement

2015 ◽  
Vol 119 (48) ◽  
pp. 11641-11649 ◽  
Author(s):  
Yosuke Sumiya ◽  
Yutaka Nagahata ◽  
Tamiki Komatsuzaki ◽  
Tetsuya Taketsugu ◽  
Satoshi Maeda
Keyword(s):  
Kinetic Analysis ◽  
Rate Constants ◽  
Claisen Rearrangement ◽  
Organic Reactions ◽  
Conformational Entropy

The chlorination of acetone: a complete kinetic analysis

1986 ◽  
Vol 64 (6) ◽  
pp. 1250-1266 ◽  
Author(s):  
J. Peter Guthrie ◽  
John Cossar
Keyword(s):  
Kinetic Analysis ◽  
Rate Constants

Rate constants are reported for all of the major steps followed in the chlorination of acetone, including the chlorination of mono- and 1,1-dichloroacetone, the chlorination of hydroxyacetone, the chlorination and hydroxide-catalyzed rearrangement of 1,1-dihydroxyacetone, and the haloform cleavage of trichloroacetone. pKa values are reported for hydroxyacetone and monochloroacetone. Rate constants for the hydrolyses of chloroacetone and 1,1-dichloroacetone are reported; these reactions are probably not SN2 displacements but proceed by addition of hydroxide and intramolecular displacement.

scholarly journals Kinetic Evidence for Near Irreversible Nonionic Micellar Entrapment ofN-(2′-Methoxyphenyl)phthalimide (1) under the Typical Alkaline Reaction Conditions

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
M. Niyaz Khan ◽  
Yoke-Leng Sim ◽  
Azhar Ariffin
Keyword(s):  
Kinetic Analysis ◽  
Alkaline Hydrolysis ◽  
Rate Constants ◽  
Total Concentration ◽  
Reaction Conditions ◽  
First Order ◽  
Order Rate ◽  
Alkaline Reaction ◽  
Pseudo First Order ◽  
Hydrolysis Of

The values of pseudo-first-order rate constants (kobs) for alkaline hydrolysis of1, obtained at 1.0 mM NaOH and withinCmEnT(total concentration ofCmEn) range of 3.0–5.0 mM forC12E23and 10–20 mM forC18E20, fail to obey pseudophase micellar (PM) model. The values of the fraction of near irreversibleCmEnmicellar trapped1molecules (FIT1) vary in the range ~0–0.75 forC12E23and ~0–0.83 forC18E20under such conditions. The values ofFIT1become 1.0 at ≥10 mMC12E23and 50 mMC18E20. Kinetic analysis of the observed data at ≥10 mMC12E23shows near irreversible micellar entrapment of1molecules under such conditions.

The Vulcanization of Elastomers. XI. The Vulcanization of Natural Rubber with Sulfur in the Presence of Mercaptobenzothiazole. I

1957 ◽  
Vol 30 (3) ◽  
pp. 911-927 ◽  
Author(s):  
Otto Lorenz ◽  
Elisabeth Echte
Keyword(s):  
Activation Energy ◽  
Zinc Oxide ◽  
Natural Rubber ◽  
Kinetic Analysis ◽  
Rate Constants ◽  
Network Formation ◽  
Zinc Salt ◽  
Kcal Mole ◽  
Minimum Quantity ◽  
First Order

Abstract 1. The decrease of free sulfur occurs according to the first order law during the vulcanization of natural rubber accelerated by mercaptobenzothiazole in the presence of zinc oxide. The activating energy for this reaction amounts to 30.5 kcal./mole. 2. If zinc benzothiazolylmercaptide is used as an accelerator, one obtains the same rate constants for the sulfur decrease as in the presence of mercaptobenzothiazole. These seem to be equivalent as regards their effectiveness of acceleration. 3. A kinetic analysis of the reciprocal swelling, which represents a measure of network formation, indicates that the reaction is first order. Sulfur decrease and reciprocal swelling prove to be equal processes as regards rate. This is true where vulcanization is accelerated with mercaptobenzothiazole or with the zinc salt. 4. During vulcanization there occurs a decrease of accelerator concentration. This is dependent upon the temperature and is tied in with the combination sulfur with rubber. 5. If the quantity of the accelerator added is changed, the rate constants for sulfur decrease and for reciprocal swelling do not change, provided that a minimum quantity of accelerator is present. 6. In vulcanization accelerated with zinc benzothiazolylmercaptide, zinc oxide being absent, sulfur decrease again occurs according to the first order law but considerably faster, without thereby changing the activation energy. These investigations are being continued and the results will be discussed in detail in relation to other published contributions in this field.

scholarly journals Kinetically Guided Radical-Based Synthesis of C(sp3)-C(sp3) Linkages on DNA

2018 ◽  
Author(s):  
Jie Wang ◽  
Helena Lundberg ◽  
Shota Asai ◽  
Pedro Martín-Acosta ◽  
Jason S. Chen ◽  
...  
Keyword(s):  
Data Mining ◽  
Pharmaceutical Industry ◽  
Kinetic Analysis ◽  
Systematic Approach ◽  
Cross Coupling ◽  
Organic Reactions ◽  
The Past ◽  
Sensitive Parameters

<div><div><div><p>DNA-encoded libraries (DEL)-based discovery platforms have recently been widely adopted in pharmaceutical industry, mainly due to its powerful diversity and incredible number of molecules. In the past two decades since its disclosure, great strides have been made to expand the toolbox of reaction modes that are compatible with the idiosyncratic aqueous, dilute, and DNA-sensitive parameters of this system. However, construction of highly important C(sp3)-C(sp3) linkages on DNA through cross-coupling remains unexplored. In this article, we describe a systematic approach to translating standard organic reactions to a DEL-setting through the tactical combination of kinetic analysis and empirical screening with information captured from data mining. To exemplify this model, implementation of the Giese addition to forge high value C–C bonds on DNA was studied, which represents the first radical-based synthesis in DEL.</p></div></div></div>

Zur Anwendung von Extinktionsdiagrammen des Stillbens in Perfluormethylcyclohexan./Kinetic Analysis of Photochemical Reactions Using Extinction Diagrams

1972 ◽  
Vol 27 (11) ◽  
pp. 1349-1353 ◽  
Author(s):  
Heinz Mauser ◽  
Hans-Joachim Niemann ◽  
Rainer Kretschmer
Keyword(s):  
Kinetic Analysis ◽  
Rate Constants ◽  
Photochemical Reaction ◽  
Photochemical Reactions ◽  
Quantum Yields ◽  
Method Of Calculation

Extinction diagrams are applied for determining the number of partial reactions. In this paper a method is described for the calculation of the concentration of the reacting substances with the aid of extinction diagrams. The concentration values are more suitable for calculation of the rate constants, and in case of photochemical reactions the partial quantum yields, than the directly measured extinction values. The method of calculation is illustrated using the photochemical reaction of stilbene in a perfluorinated solvent as an example.

Formation of Carbon Dioxide in the Belousov-Zhabotinsky-Reaction

1984 ◽  
Vol 39 (10) ◽  
pp. 993-997 ◽  
Author(s):  
H. D. Försterling ◽  
H. Idstein ◽  
R. Pachl ◽  
H. Schreiber
Keyword(s):  
Carbon Dioxide ◽  
Rate Constants ◽  
Organic Reactions ◽  
Experimental Rate ◽  
Belousov Zhabotinsky Reaction

Abstract The rate of formation of CO2 in the BZ system is measured and compared to the predictions of the Field-Körös-Noyes (FKN)-theory. The experimental rate is found to be larger than the theoretical rate by a factor of about 100. This discrepancy cannot be easily explained without severe changes in the FKN model. Moreover, improved rate constants of the most important organic reactions in the BZ system are given.

scholarly journals Mutation in the M1 Domain of the Acetylcholine Receptor α Subunit Decreases the Rate of Agonist Dissociation

1997 ◽  
Vol 109 (6) ◽  
pp. 757-766 ◽  
Author(s):  
Hai-Long Wang ◽  
Anthony Auerbach ◽  
Nina Bren ◽  
Kinji Ohno ◽  
Andrew G. Engel ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Acetylcholine Receptor ◽  
Rate Constants ◽  
Single Channel ◽  
Receptor Activation ◽  
Congenital Myasthenic Syndrome ◽  
Α Subunit ◽  
Apparent Affinity ◽  
Amino Terminal ◽  
Channel Opening

We describe the kinetic consequences of the mutation N217K in the M1 domain of the acetylcholine receptor (AChR) α subunit that causes a slow channel congenital myasthenic syndrome (SCCMS). We previously showed that receptors containing αN217K expressed in 293 HEK cells open in prolonged activation episodes strikingly similar to those observed at the SCCMS end plates. Here we use single channel kinetic analysis to show that the prolonged activation episodes result primarily from slowing of the rate of acetylcholine (ACh) dissociation from the binding site. Rate constants for channel opening and closing are also slowed but to much smaller extents. The rate constants derived from kinetic analysis also describe the concentration dependence of receptor activation, revealing a 20-fold shift in the EC50 to lower agonist concentrations for αN217K. The apparent affinity of ACh binding, measured by competition against the rate of 125I-α-bungarotoxin binding, is also enhanced 20-fold by αN217K. Both the slowing of ACh dissociation and enhanced apparent affinity are specific to the lysine substitution, as the glutamine and glutamate substitutions have no effect. Substituting lysine for the equivalent asparagine in the β, ε, or δ subunits does not affect the kinetics of receptor activation or apparent agonist affinity. The results show that a mutation in the amino-terminal portion of the M1 domain produces a localized perturbation that stabilizes agonist bound to the resting state of the AChR.

Fluorescein-photosensitized Furan Oxidation in Methanolic and Reversed Micellar Solutions, Part II Kinetic Analysis

1980 ◽  
Vol 35 (1) ◽  
pp. 107-111 ◽  
Author(s):  
Norio Miyoshi ◽  
Giiti Tomita
Keyword(s):  
Singlet Oxygen ◽  
Kinetic Analysis ◽  
Rate Constants ◽  
Solvent Polarity ◽  
Radical Mechanism ◽  
Type I ◽  
Type Ii ◽  
Micellar Solutions ◽  
Alkyl Amines ◽  
Reaction Processes

Abstract The 1,3-diphenylisobenzofuran oxidation was investigated in methanolic and dodecyl-ammonium propionate reversed micellar solutions using fluorescein sodium as photosensitizer. The furan oxidation was caused by the singlet oxygen mechanism (Type II). Aniline enhanced remarkably the furan oxidation in methanolic solutions, but inhibited highly this oxidation in the reversed micellar solutions. This enhancement of the furan oxidation was considered to be brought about by the occurrence of a radical mechanism (Type I) besides Type II mechanism. No Type I reaction occurred in the micellar solutions. The rate constants concerning with both reaction processes were evaluated by kinetic analysis, employing various aryl-and alkyl-amines. The reaction mechanism of Type I and the quenching mechanism of singlet oxygen by amines were discussed from the relationship between the rate constants, and the ionization potential of amines and the solvent polarity.

Detailed kinetics of tetrafluoroethene ozonolysis

2018 ◽  
Vol 20 (44) ◽  
pp. 28059-28067 ◽  
Author(s):  
Tam V.-T. Mai ◽  
Minh v. Duong ◽  
Hieu T. Nguyen ◽  
Lam K. Huynh
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Kinetic Analysis ◽  
Rate Constants ◽  
Rate Model ◽  
Rate Determining Step ◽  
Calculated Rate ◽  
Detailed Kinetics ◽  
Kinetics Of

The reaction mechanism was explored at the CCSD(T)/CBS//B3LYP/aug-cc-pVTZ level. Detailed kinetic analysis was firstly carried out using an ME/RRKM rate model with the inclusion of anharmonic and tunneling treatments. 1,3-Cycloaddition is found to be the rate-determining step. Calculated rate constants confirm the latest experimental data.

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