Specific rate constants for the fragmentation of vibrationally excited benzyl radicals

1999 ◽  
Vol 1 (1) ◽  
pp. 81-90 ◽  
Author(s):  
M Damm ◽  
F Deckert ◽  
H Hippler ◽  
G Rink
Keyword(s):  
Rate Constants ◽  
Specific Rate ◽  
Vibrationally Excited ◽  
Benzyl Radicals

scholarly journals Kinetic analysis of chemical reactions coupled to an enzymic step. Application to acid phosphatase assay with Fast Red

1984 ◽  
Vol 223 (3) ◽  
pp. 633-638 ◽  
Author(s):  
J Escribano ◽  
F García-Carmona ◽  
F García-Cánovas ◽  
J L Iborra ◽  
J A Lozano
Keyword(s):  
Acid Phosphatase ◽  
Chemical Reactions ◽  
Rate Constants ◽  
Diazonium Salt ◽  
Specific Rate ◽  
Fast Red ◽  
Temperature Ranges ◽  
Lag Period ◽  
Ph Range ◽  
Phosphatase Assay

Acid phosphatase assay with alpha-naphthyl phosphate as substrate and the use of diazonium salt (Fast Red TR) for chromophore formation was kinetically analysed as a system of two chemical reactions coupled to an enzymic reaction. This system follows a mechanism defined as enzymic-chemical-chemical (EzCC). The accumulation of chromophore with reaction time presented a marked lag period, which was only dependent on the rate constants of the chemical reactions and was independent of the enzymic step. The specific rate constants of each chemical step were determined in 3.8-5.0 pH and 10-35 degrees C temperature ranges. Thermodynamic parameters of the chemical steps were also obtained. Measurement of acid phosphatase activity can be carried out in the pH range 3.8-5.0 (4.8 was optimal pH) without the need to eliminate the lag period.

Channel specific rate constants for reactions of O(1D) with HCl and HBr

1986 ◽  
Vol 84 (3) ◽  
pp. 1349-1354 ◽  
Author(s):  
P. H. Wine ◽  
J. R Wells ◽  
A. R. Ravishankara
Keyword(s):  
Rate Constants ◽  
Specific Rate

Ligand substitution reactions of pentacyanoferrate(II) complexes with N-heterocyclic cations in aqueous solution

1989 ◽  
Vol 67 (11) ◽  
pp. 1774-1779 ◽  
Author(s):  
Donal Hugh Macartney ◽  
Lauren Jean Warrack
Keyword(s):  
Aqueous Solution ◽  
Rate Constants ◽  
Dissociation Constants ◽  
Formation Rate ◽  
Spectroscopic Studies ◽  
Ligand Substitution ◽  
Acid Dissociation ◽  
Specific Rate ◽  
Dissociative Mechanism ◽  
Heterocyclic Cations

Kinetic and spectroscopic studies have been carried out in aqueous solution on the formation (from Fe(CN)5OH23−) and dissociation of pentacyanoferrate(II) complexes containing 1-(4-pyridyl)pyridinium and the neutral, protonated, and N-methylated forms of 4,4′-bipyridine (BPY), 1,2-bis(4-pyridyl)ethane (BPA), and trans-1,2-bis(4-pyridyl)ethylene (BPE). The pH dependences of the formation kinetics have been analyzed in terms of the specific rate and acid dissociation constants for these ligands. The rate constants (25.0 °C, I = 0.10 M) for the formation of the dinuclear complexes (NC)5FeLFe(CN)56− have been determined for BPY (50 M−1 s−1), BPA (66 M−1 s−1), BPE (95 M−1 s−1), and pyrazine (10 M−1 s−1), and are compared with the respective rate constants for the formation of (NC)5FeLCo(NH3)5. The relationships between the formation rate constants and the size of the ligand, the number of donor sites, and the magnitude and position of charges on the ligand are discussed in terms of an ion-pair dissociative mechanism. Keywords: pentacyanoferrate(II) complexes, N-heterocycles, ligand substitution, kinetics.

Vibrational energy distribution in HF formed by elimination from activated CH3CF3 and CH2CF2

1970 ◽  
Vol 48 (18) ◽  
pp. 2919-2930 ◽  
Author(s):  
P. N. Clough ◽  
J. C. Polanyi ◽  
R. T. Taguchi
Keyword(s):  
Rate Constants ◽  
Vibrational Energy ◽  
Flow System ◽  
Relative Rate ◽  
Elimination Reaction ◽  
Vibrationally Excited ◽  
Vibrational Levels ◽  
Relative Rate Constants ◽  
Fast Flow ◽  
Vibrational Energy Distribution

The combination–elimination reaction CH3 + CF3 → CH3CF3† → CH2CF2 + HF has been studied in a fast-flow system. Infrared chemiluminescence arising from the HF product has been observed from vibrational levels v = 1–4, and relative rate constants, k(v), have been obtained for HF formation in these levels. A study has also been made of the reaction CH2CF2 + Hg*(63P1) → CHCF + HF + Hg(61S0), which has been found to produce vibrationally-excited HF. Relative rate constants k(v) for vibrational levels v = 1–4 have been obtained. It appears that channelling of the potential energy into HF vibration, in the course of the elimination step, is more efficient in the first than in the second of these reactions. In the second reaction HF is eliminated with considerable rotational excitation.

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