Modulation spectroscopy. Kinetics for the self-reactions of some α-aminoalkyl radicals in solution

1982 ◽  
Vol 60 (3) ◽  
pp. 274-278 ◽  
Author(s):  
Paul R. Marriott ◽  
Arlindo L. Castelhano ◽  
David Griller
Keyword(s):  
Absorption Spectrum ◽  
Reaction Kinetics ◽  
Unpaired Electron ◽  
Rate Constants ◽  
Lone Pair ◽  
The Self ◽  
Modulation Spectroscopy ◽  
Alkyl Radicals ◽  
Diffusion Controlled ◽  
Kinetics Of

The optical spectra and reaction kinetics of some a-aminoalkyl radicals, RĊHN(CH2R)2; R≡H, Me, Ph, were measured in solution using the technique of modulation spectroscopy. These radicals undergo diffusion controlled self-reaction with rate constants [Formula: see text]. When R≡Ph, the absorption spectrum has a well defined maximum at 346 nm; ε = 3390 M−1 cm−1, while the spectra when R≡H or Me were less intense [Formula: see text] and tailed into the visible. These spectra are substantially red-shifted when compared with those of simple alkyl radicals, an effect which is thought to be due to the interaction between the unpaired electron and the lone pair of electrons on nitrogen.

Absorption Spectrum and Reaction Kinetics of the HO2Radical in the Gas Phase

1972 ◽  
Vol 56 (9) ◽  
pp. 4426-4432 ◽  
Author(s):  
C. J. Hochanadel ◽  
J. A. Ghormley ◽  
Paul J. Ogren
Keyword(s):  
Absorption Spectrum ◽  
Reaction Kinetics ◽  
Gas Phase ◽  
Kinetics Of

Electron transfer kinetics of cobaloxime complexes

1996 ◽  
Vol 74 (5) ◽  
pp. 658-665 ◽  
Author(s):  
Kefei Wang ◽  
R.B. Jordan
Keyword(s):  
Electron Transfer ◽  
Exchange Rate ◽  
Rate Constants ◽  
Ph Dependence ◽  
Outer Sphere ◽  
The Self ◽  
Oxidation Of Co ◽  
Reduction Potentials ◽  
Inner Sphere ◽  
Kinetics Of

The rates of oxidation of CoII(dmgBF2)2(OH2)2 by CoIII(NH3)5X2+ (X = Br−, Cl−, and N3−) have been studied at 25 °C in 0.10 M LiClO4. The rate constants are 50 ± 9, 2.6 ± 0.2, and 5.9 ± 1.0 M−1 s−1 for X = Br−, Cl−, and N3−, respectively, in 0.01 M acetate buffer at pH 4.7. The relative rates are consistent with the inner-sphere bridging mechanism established earlier by Adin and Espenson for the analogous reactions of CoII(dmgH)2(OH2)2. The rate constants with CoII(dmgBF2)2(OH2)2 typically are ~103 times smaller and this is attributed largely to the smaller driving force for the CoII(dmgBF2)2(OH2)2 complex. The outer-sphere oxidations of cobalt(II) sepulchrate by CoIII(dmgH)2(OH2)2+ (pH 4.76–7.35, acetate, MES, and PIPES buffers) and CoIII(dmgBF2)2(OH2)2+ (pH 3.3–7.42, chloroacetate, acetate, MES, and PIPES buffers) have been studied. The pH dependence gives the following rate constants (M−1 s−1) for the species indicated: (1.55 ± 0.09) × 105 (CoIII(dmgBF2)2(OH2)2+); (5.5 ± 0.3) × 103 (CoII(dmgH)2(OH2)2+); (3.1 ± 0.5) × 102 (CoIII(dmgH)2(OH2)(OH)); (2.5 ± 0.3) × 102 (CoIII(dmgBF2)2(OH2)(OH)). The known reduction potentials for cobalt(III) sepulchrate and the diaqua complexes, and the self-exchange rate for cobalt(II/III) sepulchrate, are used to estimate the self-exchange rate constants for the dioximate complexes. Comparisons to other reactions with cobalt sepulchrate indicates best estimates of the self-exchange rate constants are ~2.4 × 10−2 M−1 s−1 for CoII/III(dmgH)2(OH2)2and ~5.7 × 10−3 M−1 s−1 for CoII/III(dmgBF2)2(OH2)2. Key words: electron transfer, cobaloxime, inner sphere, outer sphere, self-exchange.

scholarly journals Reaction Kinetics of Carbon Dioxide in Aqueous Diethanolamine Solutions Using the Stopped-Flow Technique

2012 ◽  
Vol 19 (1) ◽  
pp. 55-66 ◽  
Author(s):  
Marta Siemieniec ◽  
Hanna Kierzkowska-Pawlak ◽  
Andrzej Chacuk
Keyword(s):  
Carbon Dioxide ◽  
Reaction Kinetics ◽  
Rate Constants ◽  
Reaction Rate ◽  
Reaction Rate Constant ◽  
Stopped Flow ◽  
First Order ◽  
Pseudo First Order ◽  
Kinetics Of ◽  
Good Agreement

Reaction Kinetics of Carbon Dioxide in Aqueous Diethanolamine Solutions Using the Stopped-Flow Technique The pseudo-first-order rate constants (kOV) for the reactions between CO2 and diethanolamine have been studied using the stopped-flow technique in an aqueous solution at 293, 298, 303 and 313 K. The amine concentrations ranged from 167 to 500 mol·m-3. The overall reaction rate constant was found to increase with amine concentration and temperature. Both the zwitterion and termolecular mechanisms were applied to correlate the experimentally obtained rate constants. The values of SSE quality index showed a good agreement between the experimental data and the corresponding fit by the use of both mechanisms.

Relationships among structure, reactivity towards thiols and basicity of phenylhydrazonopropanedinitriles

1985 ◽  
Vol 50 (9) ◽  
pp. 2065-2076 ◽  
Author(s):  
Ernest Šturdík ◽  
Marián Antalík ◽  
Pavol Sulo ◽  
Štefan Baláž ◽  
Edita Ďurčová ◽  
...  
Keyword(s):  
Reaction Kinetics ◽  
Rate Constants ◽  
Simple Relation ◽  
Second Order ◽  
Spectrophotometric Investigation ◽  
Hammett Constants ◽  
Similar Dependence ◽  
Kinetics Of ◽  
Derivatives Of

Data required for characterization of reactivity of ortho-, meta-, and para-substituted derivatives by first and second order rate constants were obtained from spectrophotometric investigation of reaction kinetics of phenylhydrazonopropanedinitriles with model thiols. The reactivity has been found to be linearly dependent on Hammett constants of substituents. Similar dependence revealed the basicity characterized by pKa values determined spectrophotometrically. Whilst reactivity and basicity of meta- and para-substituted derivatives is dependent, ortho-substituted derivatives did not obey any simple relation between reactivity and basicity. This finding is important for utilization of ortho-derivatives of phenylhydrazonopropanedinitrile when studying the uncoupling effect of these substances upon oxidative and photosynthetic phosphorylation.

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