Relative reactivities of dihydrophenazine and dihydrophenazonium radicals in electron-transfer to an azobenzene

1970 ◽  
Vol 48 (17) ◽  
pp. 2718-2721 ◽  
Author(s):  
Richard L. Reeves
Keyword(s):  
Electron Transfer ◽  
Sulfuric Acid ◽  
Kinetic Study ◽  
Rate Constant ◽  
Transfer Reaction ◽  
Order Rate Constant ◽  
Electron Transfer Reaction ◽  
Second Order ◽  
Aqueous Acetonitrile ◽  
Predominant Species

A kinetic study of the electron-transfer reaction between a model azobenzene and dihydrophenazonium ion-radical and dihydrophenazine was carried out in 0.2 N sulfuric acid in 50 v/v aqueous acetonitrile. The second-order rate constant for the dihydrophenazine is greater than that of the ion-radical by a factor of 104. It is shown that in solutions in which the ion-radical is the predominant species, the principal electron-transfer agent is the dihydrophenazine formed by dismutation of the radical.

FT-EPR Study of Spin-correlated Radical Pairs Formed by Electron Transfer Quenching of Porphyrin Triplets in Micellar Solution

1998 ◽  
Vol 02 (04) ◽  
pp. 353-361 ◽  
Author(s):  
VOLKER WEIS ◽  
HANS VAN WILLIGEN
Keyword(s):  
Electron Transfer ◽  
Statistical Model ◽  
Rate Constant ◽  
Micellar Solution ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Cetyltrimethylammonium Chloride ◽  
Radical Pairs ◽  
Homogeneous Solutions ◽  
Kinetics Of

The spin-correlated radical pairs (SCRPs) formed by photoinduced electron transfer from zinc tetrakis(4-sulfonatophenyl)porphyrin ( ZnTPPS ) to quinones in micelles of the cationic surfactant cetyltrimethylammonium chloride ( CTAC ) were studied by means of Fourier transform EPR (FT-EPR). It is shown that variation of the power of the microwave pulse allows the separation of EPR signals arising from SCRPs and free radicals. The measured kinetics of radical formation can be accounted for in terms of a statistical model taking into account the non-uniform distribution of the solutes over the micelles. The rate constant of electron transfer quenching (kq) of the ZnTPPS triplet state by duroquinone (DQ) is found to be 1.05 × 106 s−1. The FT-EPR measurements gave information also on the kinetics of the homogeneous electron transfer reaction DQ − + DQ → DQ + DQ − in CTAC solution in which the DQ − anion radicals were generated by light-induced electron transfer from ZnTPPS . It is found that the dependence of the rate of this reaction on quinone concentration deviates from the linear relationship found in homogeneous solutions. A statistical model is proposed to account for the data. Based on this model, the rate constant of the self-exchange reaction (k ex ) is 4.1 × 106 s−1. From results obtained with duroquinone and benzoquinone as acceptors, it is concluded that ZnTPPS is located at the micelle/water interface.

Electron Transfer Reaction of Ion Pairs: 1.  Surfactant Cobalt(III) Complexes by Fe(CN)64− in Microheterogeneous Media

2015 ◽  
Vol 229 (3) ◽  
Author(s):  
Karuppiah Nagaraj ◽  
Krishnan Senthil Murugan ◽  
Pilavadi Thangamuniyandi
Keyword(s):  
Electron Transfer ◽  
Kinetic Study ◽  
Transfer Reaction ◽  
Ion Pairs ◽  
Electron Transfer Reaction ◽  
Single Chain ◽  
Microheterogeneous Media

AbstractThe kinetic study of reduction of single chain surfactant octahedral cobalt(III) complexes,

scholarly journals Kinetics and Mechanism of Oxidation of L-Ascorbic Acid by Pt(IV)(aq) in Aqueous Hydrochloric Acid Medium

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Sadhana Senapati ◽  
S. P. Das ◽  
A. K. Patnaik
Keyword(s):  
Electron Transfer ◽  
Ascorbic Acid ◽  
Acid Medium ◽  
Redox Reaction ◽  
Transfer Reaction ◽  
Total Concentration ◽  
Activation Parameters ◽  
Order Rate Constant ◽  
Electron Transfer Reaction ◽  
Reaction Products

Reduction of [PtCl6]2− by L-ascorbic acid (H2ASc) in 0.1 M aqueous acid medium has been investigated spectrophotometrically under pseudo-first order condition at [PtCl6]2− = 0.005–0.007 mol dm−3, 0.05 ≤ [H2ASc]/mol dm−3 ≤ 0.3, 298 K ≤ T ≤ 308 K, [H+] = 0.14 mol dm−3, I=0.5 mol dm−3. The redox reaction follows the rate law: d[Pt(IV)]/dt = k[H2ASc][Pt(IV)], where k is the second-order rate constant and [H2ASc] is the total concentration of ascorbic acid. Electron transfer from [H2ASc] to Pt(IV) center leading to the release of two halide ions and formation of the reaction products, square planner Pt(II) halide complex, and dehydrated ascorbic acid is suggested. This redox reaction follows an outersphere mechanism as Pt(IV) complex is substituted inert. Activation parameters were calculated corresponding to rate of electron transfer reaction k. Activation parameters favor the electron transfer reaction.

scholarly journals Kinetic Study on Induced Electron Transfer Reaction in Pentaamminecobalt(III) Complexes of α-Hydroxy Acids by Pyridinium Fluorochromate in Micellar Medium

2011 ◽  
Vol 8 (3) ◽  
pp. 1102-1107
Author(s):  
B. Mohammed Nawaz ◽  
K. Subramani ◽  
Mansur Ahmed
Keyword(s):  
Electron Transfer ◽  
Kinetic Study ◽  
Carbonyl Compounds ◽  
Transfer Reaction ◽  
Electron Transfer Reaction ◽  
Micellar Medium ◽  
Hydroxy Acids ◽  
Uv Visible ◽  
Pyridinium Fluorochromate

Pyridinium fluorochromate (PFC) oxidation of pentaamminecobalt(III) complexes of α-hydroxy acids in micellar medium yielding nearly 100% of carbonyl compounds are ultimate products. The decrease in UV-visible absorbance at λ=502 nm for Co(III) complex corresponds to nearly 100% of the initial absorbance. The stoichiometry of unbound ligand and cobalt(III) complex is accounting for about 100% reduction at the cobalt(III) centre. The kinetic and stoichiometric results have been accounted by a suitable mechanism.

A Kinetic Study of the Electron-Transfer Reaction of the Phthalimide-N-oxyl Radical (PINO) with Ferrocenes

2007 ◽  
Vol 72 (23) ◽  
pp. 8748-8754 ◽  
Author(s):  
Enrico Baciocchi ◽  
Massimo Bietti ◽  
Massimo Di Fusco ◽  
Osvaldo Lanzalunga
Keyword(s):  
Electron Transfer ◽  
Kinetic Study ◽  
Transfer Reaction ◽  
Electron Transfer Reaction
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