Amine autoxidation in aqueous solution

1983 ◽  
Vol 36 (4) ◽  
pp. 719 ◽  
Author(s):  
ALJ Beckwith ◽  
PH Eichinger ◽  
BA Mooney ◽  
RH Prager
Keyword(s):  
Aqueous Solution ◽  
Electron Transfer ◽  
Free Radical ◽  
Electron Acceptors ◽  
Hydroxyl Groups ◽  
Free Base ◽  
Strong Electron ◽  
Radical Initiators ◽  
Mechanism Of Oxidation ◽  
Radical Traps

The uncatalysed autoxidation of aqueous solutions of tertiary aliphatic amines has been studied in order to obtain information concerning the mechanism of oxidation of Sirotherm resins. Oxidation occurs most rapidly in the free base, and the general correlation of rate with pK, or ionization potential suggests that electron transfer to form an aminium radical cation is rate-determining. The reaction is not initiated by free radical initiators, nor inhibited by radical traps. It is significantly catalysed by strong electron acceptors and by light and is moderately inhibited by the electron donor N-phenylanthranilic acid. Pyrrolidines and hexahydroazepines are oxidized faster than piperidines, and hydroxyl groups on β-carbons increase the rate of oxidation, while those on γ-carbons decrease it. The major products of autoxidation of alkyl pyrrolidines in water were found to be N-oxides. Various pyrrolidinones were isolated in smaller yield.

Kinetics of the photochemical reactions of the croconate dianion in aqueous solution

1992 ◽  
Vol 70 (1) ◽  
pp. 135-143 ◽  
Author(s):  
B Zhao ◽  
M. H. Back
Keyword(s):  
Aqueous Solution ◽  
Electron Transfer ◽  
Quantum Yield ◽  
Rate Constants ◽  
Photochemical Reactions ◽  
Electron Acceptors ◽  
Basic Solution ◽  
Hydroxyl Ion ◽  
Kinetics Of

The kinetics of the photochemical reactions of the dianion of croconic acid (1,2-dihydroxycyclopentenetrione) have been studied in aqueous solution in the presence of electron acceptors. In neutral solutions the quantum yield for disappearance of croconate dianion was small (< 10−3) but was substantially increased in basic solution and in the presence of electron acceptors. At pH 12 in the presence of 4-nitrobenzylbromide and biacetyl a quantum yield of 1 was obtained. The kinetics of the rate of disappearance of croconate dianion as a function of pH and concentration of acceptor showed that the excited dianion is oxidized by acceptors and reacts with hydroxyl ion. A mechanism is proposed that, by assuming reasonable values for the rate constants involved, is shown to be consistent with the results. Keywords: photolysis, kinetics, croconate dianion, electron transfer.

Photoinduced electron transfer across an organic molecular wall: octa acid encapsulated ESIPT dyes as electron donors

2017 ◽  
Vol 16 (6) ◽  
pp. 840-844 ◽  
Author(s):  
Fabiano S. Santos ◽  
Elamparuthi Ramasamy ◽  
V. Ramamurthy ◽  
Fabiano S. Rodembusch
Keyword(s):  
Aqueous Solution ◽  
Electron Transfer ◽  
Proton Transfer ◽  
Photoinduced Electron Transfer ◽  
Electron Acceptors ◽  
Water Soluble ◽  
Electron Donors ◽  
Octa Acid

Efficient photoinduced electron transfer from proton transfer dyes encapsulated within water soluble supramolecular host octa acid to electron acceptors present outside the capsule was observed in aqueous solution.

Relative Reactivities of 1,1,1-Trichloroethane and 1,1,1-Trichlorotrifluoroethane in Competitive Addition Reactions

1992 ◽  
Vol 57 (6) ◽  
pp. 1291-1298 ◽  
Author(s):  
František Adámek ◽  
Milan Hájek ◽  
Zbyněk Janoušek
Keyword(s):  
Free Radical ◽  
Reaction Mechanism ◽  
Relative Reactivity ◽  
Addition Reactions ◽  
Radical Initiation ◽  
Amine Complexes ◽  
Free Radical Initiation ◽  
Ru Complexes ◽  
Radical Initiators

Relative reactivity of CH3CCl3 and CF3CCl3 measured in competitive addition reactions with 1-hexene in the presence of free radical initiators or Cu, Pd and Ru complexes was found to depend on the type of catalyst. The unusual course of the reaction has been found in the additions catalyzed with copper(I)-amine complexes where CH3CCl3 in competition with CF3CCl3 was completely unreactive. The results have been explained in terms of the change of reaction mechanism and compared with classical free radical initiation.

Study of aerobic oxidation of phenyl PtII complexes (dpms)PtIIPh(L) (dpms = di(2-pyridyl)methanesulfonate; L = water, methanol, or aniline)

2009 ◽  
Vol 87 (1) ◽  
pp. 110-120 ◽  
Author(s):  
Julia R Khusnutdinova ◽  
Peter Y Zavalij ◽  
Andrei N Vedernikov
Keyword(s):  
Aqueous Solution ◽  
Aerobic Oxidation ◽  
Reductive Elimination ◽  
High Yield ◽  
Ambient Conditions ◽  
Activation Barriers ◽  
Methanol Solutions ◽  
Anionic Species ◽  
Mechanism Of Oxidation ◽  
Solution Mechanism

Oxidation of phenyl PtII complexes K[(dpms)PtIIPh2], 1, (dpms)PtIIPh(MeOH), 2, (dpms)PtIIPh(OH2), 3, and methyl PtII complex (dpms)PtIIMe(NH2Ph), 6, with O2 in aqueous or methanol solutions under ambient conditions leads to corresponding (dpms)PtIVR(X)OH complexes (R = X = Ph, 7; R = Ph, X = OH, 8; R = Ph, X = OMe, 9; R = Me, X = NHPh; 11; dpms = di(2-pyridyl)methanesulfonate). Complexes 7–9 could be isolated in high yield. Complex 11 as well as its phenyl analogue (dpms)PtIVPh(NHPh)OH, 10 can be prepared in high yield by oxidation of corresponding (dpms)PtIIR(NH2Ph) with H2O2 in methanol. Phenyl PtII complexes (dpms)PtIIPh(HX) derived from HX = aniline and DMSO, 4 and 5, respectively, are inert toward O2. The rate of oxidation of 1–5 with O2 decreases in the order 1 > 3 ~ 2 » 4, and 5 is unreactive. Methyl analogues are significantly more reactive compared with their phenyl counterparts. Proposed mechanism of oxidation with O2 includes formation of anionic species (dpms)PtIIR(X)– responsible for reaction with dioxygen. Attempts at C–O and C–N reductive elimination from phenyl PtIV complexes 7–10 do not lead to phenyl derivatives PhX at 80–100 °C, consistent with the results of the DFT estimates of corresponding activation barriers, ΔG0 exceeding 28 kcal/mol.Key words: platinum phenyl complexes, oxidation, dioxygen, aqueous solution, mechanism.

scholarly journals Alternative Mitochondrial Electron Transfer as a Novel Strategy for Neuroprotection

2011 ◽  
Vol 286 (18) ◽  
pp. 16504-16515 ◽  
Author(s):  
Yi Wen ◽  
Wenjun Li ◽  
Ethan C. Poteet ◽  
Luokun Xie ◽  
Cong Tan ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Free Radical ◽  
Cerebral Ischemia ◽  
Complex I ◽  
Focal Cerebral Ischemia ◽  
Neurological Diseases ◽  
Ischemia Reperfusion ◽  
Free Radical Scavengers ◽  
Mitochondrial Complex ◽  
Novel Strategy

Neuroprotective strategies, including free radical scavengers, ion channel modulators, and anti-inflammatory agents, have been extensively explored in the last 2 decades for the treatment of neurological diseases. Unfortunately, none of the neuroprotectants has been proved effective in clinical trails. In the current study, we demonstrated that methylene blue (MB) functions as an alternative electron carrier, which accepts electrons from NADH and transfers them to cytochrome c and bypasses complex I/III blockage. A de novo synthesized MB derivative, with the redox center disabled by N-acetylation, had no effect on mitochondrial complex activities. MB increases cellular oxygen consumption rates and reduces anaerobic glycolysis in cultured neuronal cells. MB is protective against various insults in vitro at low nanomolar concentrations. Our data indicate that MB has a unique mechanism and is fundamentally different from traditional antioxidants. We examined the effects of MB in two animal models of neurological diseases. MB dramatically attenuates behavioral, neurochemical, and neuropathological impairment in a Parkinson disease model. Rotenone caused severe dopamine depletion in the striatum, which was almost completely rescued by MB. MB rescued the effects of rotenone on mitochondrial complex I-III inhibition and free radical overproduction. Rotenone induced a severe loss of nigral dopaminergic neurons, which was dramatically attenuated by MB. In addition, MB significantly reduced cerebral ischemia reperfusion damage in a transient focal cerebral ischemia model. The present study indicates that rerouting mitochondrial electron transfer by MB or similar molecules provides a novel strategy for neuroprotection against both chronic and acute neurological diseases involving mitochondrial dysfunction.

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