Correlation of Calculated Activation Energies with Experimental Rate Constants for an Enzyme Catalyzed Aromatic Hydroxylation

1998 ◽  
Vol 120 (30) ◽  
pp. 7641-7642 ◽  
Author(s):  
Lars Ridder ◽  
Adrian J. Mulholland ◽  
Jacques Vervoort ◽  
Ivonne M. C. M. Rietjens
Keyword(s):  
Rate Constants ◽  
Activation Energies ◽  
Experimental Rate ◽  
Aromatic Hydroxylation ◽  
Calculated Activation

Kinetics of esterification of monoisopropylphenols with phosphoryl trichloride

1989 ◽  
Vol 54 (5) ◽  
pp. 1311-1317
Author(s):  
Miroslav Magura ◽  
Ján Vojtko ◽  
Ján Ilavský
Keyword(s):  
Liquid Phase ◽  
Rate Constants ◽  
Reaction Rates ◽  
Activation Energies ◽  
The Individual ◽  
Kinetics Of

The kinetics of liquid-phase isothermal esterification of POCl3 with 2-isopropylphenol and 4-isopropylphenol have been studied within the temperature intervals of 110 to 130 and 90 to 110 °C, respectively. The rate constants and activation energies of the individual steps of this three-step reaction have been calculated from the values measured. The reaction rates of the two isomers markedly differ: at 110 °C 4-isopropylphenol reacts faster by the factors of about 7 and 20 for k1 and k3, respectively. This finding can be utilized in preparation of mixed triaryl phosphates, since the alkylation mixture after reaction of phenol with propene contains an excess of 2-isopropylphenol over 4-isopropylphenol.

Reactions of trifluoromethyl radicals. V. Hydrogen abstraction from methyl acetate and methyl (2H3)Acetate

1980 ◽  
Vol 33 (7) ◽  
pp. 1437
Author(s):  
NL Arthur ◽  
PJ Newitt
Keyword(s):  
Isotope Effect ◽  
Rate Constants ◽  
Methoxy Group ◽  
Methyl Acetate ◽  
Kinetic Isotope Effect ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Temperature Range ◽  
Kinetic Isotope ◽  
Acetyl Group

Hydrogen abstraction by CF3 radicals from CH3COOCH3 and CD3COOCH3 has been studied in the temperature range 78-242°, and data have been obtained for the reactions: CF3 + CH3COOCH3 → CF3H+[C3H5O2] �������������(3) CF3 + CH3COOCH3 → CF3H+CH2COOCH3������������ (4) CF3 + CD3COOCH3 → CF3D+CD2COOCH3������������ (6) CF3 + CD3COOCH3 → CF3H+CD3COOCH2������������ (7) The corresponding rate constants, based on the value of 1013.36 cm3 mol-1 S-1 for the recombination of CF3 radicals, are given by (k in cm3 mol-1 s-1 and E in J mol-1): logk3 = (11.52�0.05)-(35430�380)/19.145T ���� (3)logk4 = (11.19�0.07)-(34680�550)/19.145T ���� (4)logk6 = (11.34�0.06)-(46490�490)/19.145T ���� (6)logk7 = (11.26�0.05)-(36440�400)/19.145T ���� (7)At 400 K, 59% of abstraction occurs from the acetyl group, and 41 % from the methoxy group. The kinetic isotope effect at 400 K for attack on the acetyl group is 25, due mainly to a difference in activation energies.

The reactions of O(3P) with 2-propanone, 2-butanone, and 3-pentanone

1986 ◽  
Vol 64 (7) ◽  
pp. 1408-1414 ◽  
Author(s):  
John M. Roscoe
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Substrate Concentration ◽  
Activation Energies ◽  
Absolute Rate ◽  
The Absolute

The reactions of O(3P) with 2-propanone, 2-butanone, and 3-pentanone have been studied kinetically as a function of temperature and substrate concentration. The absolute rate constants for these reactions in the gas phase, in the units M−1 s−1, obey the following relations.[Formula: see text]The activation energies for these reactions are comparable to those for the reactions of O(3P) with alcohols, but the preexponential factors for the reactions of O(3P) with these ketones are significantly smaller than those for the analogous reactions with alcohols. The available data indicate that the reactivity of O(3P) toward ketones shows a variation with polar effects of substituents which is similar to that found for the reactions of OH with ketones.

THE REACTIONS OF TRIFLUOROMETHYL RADICALS WITH PROPANE, n-BUTANE, AND ISOBUTANE

1956 ◽  
Vol 34 (2) ◽  
pp. 103-107 ◽  
Author(s):  
P. B. Ayscough ◽  
E. W. R. Steacie
Keyword(s):  
Rate Constants ◽  
Hydrogen Abstraction ◽  
Activation Energies ◽  
Methyl Radicals ◽  
Kcal Mole

A study of the reactions of trifluoromethyl radicals, produced by the photolysis of hexafluoroacetone, with propane, n-butane, and isobutane has been made. The rate constants of the hydrogen-abstraction reactions have been determined at temperatures between 27 °C and 119 °C and the activation energies found to be 6.5 ± 0.5, 5.1 ± 0.3, and 4.7 ± 0.3 kcal./mole respectively. These values are compared with those obtained for the reactions with methane and ethane, and with the corresponding reactions of methyl radicals.

Reaction between alkali metal ferrocyanides and persulfates in aqueous solution

1967 ◽  
Vol 45 (20) ◽  
pp. 2411-2418 ◽  
Author(s):  
R. W. Chlebek ◽  
M. W. Lister
Keyword(s):  
Aqueous Solution ◽  
Alkali Metal ◽  
Rate Constants ◽  
Ion Pairs ◽  
Metal Cations ◽  
Activation Energies ◽  
Alkali Metal Cations ◽  
Potassium Salts ◽  
Apparent Activation Energies

The rates of the reaction of ferrocyanide and persulfate ions, in the presence of various concentrations of different alkali metal cations, have been measured at various temperatures and ionic strengths. The results are interpreted in terms of ion pairs and support the view that the actual reacting species are MFe(CN)6−3 and MS2O8−, where M is an alkali metal. This is similar to the situation found earlier for potassium salts of these ions. The rate constants obtained on this assumption increase gradually from lithium to cesium. Values are also obtained for the apparent activation energies of these reactions.

THE REACTIONS OF ACTIVE NITROGEN WITH THE BUTANES

1954 ◽  
Vol 32 (7) ◽  
pp. 718-724 ◽  
Author(s):  
R. A. Back ◽  
C. A. Winkler
Keyword(s):  
Nitrogen Atom ◽  
Rate Constants ◽  
Hydrogen Cyanide ◽  
Main Product ◽  
Activation Energies ◽  
Reactive Species ◽  
Atomic Nitrogen ◽  
Initial Attack ◽  
Active Nitrogen ◽  
Rate Controlling Step

The main product of the reactions of active nitrogen with n- and iso-butanes at 75 °C. and 250 °C. was hydrogen cyanide. Small amounts of C2 hydrocarbons, mainly ethylene and acetylene, were produced in both reactions. Second order rate constants were calculated on the assumption that the reactive species in active nitrogen is atomic nitrogen, and that the initial attack of a nitrogen atom is the rate-controlling step. The activation energies were then estimated to be 3.6 kcal. and 3.1 kcal. and the probability factors 4.5 × 10−4 and 4.4 × 10−4, for the n-butane and isobutane reactions respectively.

Effects of oxidant concentration and temperature on decolorization of azo dye: comparisons of UV/Fenton and UV/Fenton-like systems

2012 ◽  
Vol 65 (11) ◽  
pp. 1970-1974 ◽  
Author(s):  
C. Y. Kuo ◽  
C. Y. Pai ◽  
C. H. Wu ◽  
M. Y. Jian
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Azo Dye ◽  
Activation Energies ◽  
First Order ◽  
First Order Kinetics ◽  
Oxidant Concentration ◽  
Decolorization Efficiency ◽  
Pseudo First Order ◽  
Reactive Red 2

This study applies photo-Fenton and photo-Fenton-like systems to decolorize C.I. Reactive Red 2 (RR2). The oxidants were H2O2 and Na2S2O8; Fe2+, Fe3+, and Co2+ were used to activate these two oxidants. The effects of oxidant concentration (0.3–2 mmol/L) and temperature (25–55 °C) on decolorization efficiency of the photo-Fenton and photo-Fenton-like systems were determined. The decolorization rate constants (k) of RR2 in the tested systems are consistent with pseudo-first-order kinetics. The rate constant increased as oxidant concentration and temperature increased. Activation energies of RR2 decolorization in the UV/H2O2/Fe2+, UV/H2O2/Fe3+, UV/Na2S2O8/Fe2+ and UV/Na2S2O8/Fe3+ systems were 32.20, 39.54, 35.54, and 51.75 kJ/mol, respectively.

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