scholarly journals Erratum: Transition states and rate constants for ion–molecule association. II. Li++(CH3)2O→Li+[(CH3)2O] [J. Chem. Phys. 86, 1348 (1986)]

1987 ◽  
Vol 86 (12) ◽  
pp. 7250-7250
Author(s):  
Scott R. Vande Linde ◽  
Sandra L. Mondro ◽  
William L. Hase
Keyword(s):  
Rate Constants ◽  
Transition States ◽  
Chem Phys

Substituent effects of rate constants for thermal [4π + 2π] cycloreversion of spiro-fused β-lactam oxadiazolines

1993 ◽  
Vol 71 (6) ◽  
pp. 907-911 ◽  
Author(s):  
Michel Zoghbi ◽  
John Warkentin
Keyword(s):  
Thermal Decomposition ◽  
Rate Constant ◽  
Rate Constants ◽  
Transition States ◽  
Substituent Effects ◽  
Ground States ◽  
Phenyl Substituent ◽  
First Order ◽  
Average Value ◽  
Carbonyl Ylide

Twelve Δ3-1,3,4-oxadiazolines in which C-2 is also C-4 of a β-lactam moiety (spiro-fused β-lactam oxadiazoline system) were thermolyzed as solutions in benzene. Substituents in the β-lactam portion affect the rate constant for thermal decomposition of the oxadiazolines to N2, acetone, and a β-lactam-4-ylidene. The total spread of first-order rate constants at 100 °C was 47-fold and the average value was 6.7 × 10−4 s−1. A phenyl substituent at N-1 or at C-3 was found to be rate enhancing, relative to methyl. At C-3, H and Cl were also rate enhancing, relative to methyl. The data are interpreted in terms of the differential effects of substituents on the stabilities of the ground states, and on the stabilities of corresponding transition states for concerted, suprafacial, [4π + 2π] cycloreversion. The first products, presumably formed irreversibly, are N2 and a carbonyl ylide. The latter subsequently fragments to form acetone (quantitative) and a β-lactam-4-ylidene.

Studies in solvolysis. Part VIII. An entropy correlation related to the reaction of various nucleophiles with malachite green

1977 ◽  
Vol 55 (4) ◽  
pp. 686-692 ◽  
Author(s):  
Stephen Harvey Morris ◽  
John Marshall William Scott ◽  
Frederick Steele
Keyword(s):  
Temperature Dependence ◽  
Malachite Green ◽  
Methyl Iodide ◽  
Rate Constants ◽  
Transition States ◽  
Reaction Coordinate ◽  
Similar Correlation ◽  
Displacement Reactions

The entropies of activation related to the reactions of aqueous malachite green with the nucleophiles water, hydroxide, hydrazine, ammonia, hypochlorite, and sulphite have been calculated from the temperature dependence of the rate constants appropriate to these reactions. The entropies of the transition states for these reactions have been characterized and the transition states shown to be 'reactant like'. A similar correlation, based on data for a series of nucleophiles attacking methyl iodide, suggests that the transition states for the SN2 displacement reactions are also 'reactant like' with respect to the attacking nucleophile. A relationship between two distinct parameters each of which is related to the position of transition states along the reaction coordinate is considered.

The Hydrolysis of Bis(2-chloroethyl) Sulfide (Sulfur Mustard) in Aqueous Mixtures of Ethanol, Acetone and Dimethyl Sulfoxide

1993 ◽  
Vol 46 (3) ◽  
pp. 293 ◽  
Author(s):  
RI Tilley
Keyword(s):  
Transition State ◽  
Dimethyl Sulfoxide ◽  
Rate Constants ◽  
Charge Separation ◽  
Sulfur Mustard ◽  
Transition States ◽  
Aqueous Mixtures ◽  
Sulfide Sulfur ◽  
Rate Of Hydrolysis ◽  
Hydrolysis Of

The rate of hydrolysis of bis (2-chloroethyl) sulfide (sulfur mustard) in aqueous mixtures of ethanol, acetone and dimethyl sulfoxide has been measured and compared with previously reported values. Rate constants in water at 25°C for the two consecutive hydrolysis reactions undergone by sulfur mustard were estimated to be (2.93�0.15)×10-3 and (3.87�0.14)×10-3 s-1. Charge separation of 0.42 in the transition states was indicated together with significant solvation of the positive end of the transition state dipoles.

Substituent and solvent effects on the reaction between 2,6-Di-t-butyl-α-(3,5-di-t-butyl-4-oxocyclohexa-2,5-dien-1-ylidene)-p-tolyloxyl (galvinoxyl) and phenols

1978 ◽  
Vol 31 (6) ◽  
pp. 1201 ◽  
Author(s):  
N Nishimura ◽  
K Okahashi ◽  
T Yukutomi ◽  
A Fujiwara ◽  
S Kubo
Keyword(s):  
Carbon Tetrachloride ◽  
Binary Mixtures ◽  
Solvent Effects ◽  
Rate Constants ◽  
Isotope Effects ◽  
Mixed Solvents ◽  
Transition States ◽  
Activation Parameters ◽  
Substituted Phenols ◽  
Kinetic Behaviour

Rate constants and associated activation parameters for the reaction of galvinoxyl with substituted phenols were obtained in carbon tetrachloride and in cyclohexane-dioxan binary mixtures. Substantial isotope effects were observed for O-deuterated phenols. The rate constants are correlated with σ+ values. These findings are discussed by considering the polar contribution of substituents to the stabilization of the transition states. In the mixed solvents, the kinetic behaviour is well expressed by the equations which are based on the theory of Kondo and Tokura.

scholarly journals Anharmonic effect of the rate constant of the reactions of CH3SCH2OO system in high-temperature combustion

2017 ◽  
Vol 95 (10) ◽  
pp. 1064-1072 ◽  
Author(s):  
Yu Hao ◽  
Xinxiang Pan ◽  
Liguo Song ◽  
Yang Ding ◽  
Wenwen Xia ◽  
...  
Keyword(s):  
High Temperature ◽  
Total Energy ◽  
Rate Constant ◽  
Rate Constants ◽  
Transition States ◽  
Main Reaction ◽  
Anharmonic Effect ◽  
Barrier Heights ◽  
Temperature Combustion ◽  
High Temperature Combustion

The study mainly focuses on the anharmonic effect of the reactions of CH3SCH2OO system. The geometries of the reactants and the transition states are optimized with Gaussian 09. The barrier heights are calculated with the energy of the reactants and the transition states. The RRKM theory is utilized to calculate the anharmonic and harmonic rate constants of the reactions. The anharmonic effect of these reactions can be clearly demonstrated by our results. Generally speaking, in the study, for most reactions, the rate constants increase with the temperature in the canonical case and the total energy in the microcanonical case, and the anharmonic effect of these reactions is significant and should not be neglected in high-temperature combustion. In CH3SCH2OO system, CH3SCH2OO → CH2SCH2OOH → CH2S + CH2O + OH is the main reaction channel. After a series of calculations, the anharmonic effect is remarkable, especially in high-temperature combustion. By analyzing other meaningful reactions that followed that channel above, the anharmonic effect of these reactions is generally obvious enough, especially for those reactions whose barrier heights are relatively low.

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