Photoreduction by amines

Cohen, Saul G.; Parola, Abraham H.; Parsons, George H.

doi:10.1021/cr60282a004

Cited by 645 publications

(279 citation statements)

References 17 publications

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“…Moreover, the reaction rate for the three drugs in the deoxygenated aqueous HS solution was in the order: diphenhydramine > propranolol > mexiletine (Figure 2). This was in satisfactory agreement with the common reaction order, namely, tertiary amine > secondary amine > primary amine for the photooxidation of amines by ketones sensitizer in various deoxygenated organic solutions (39). It has been demonstrated that the p-π conjugation effect was unfavorable to the photooxidation of the amine drugs.…”

Section: Kinetics Of Photodegradationsupporting

confidence: 84%

Indirect Photodegradation of Amine Drugs in Aqueous Solution under Simulated Sunlight

Chen

et al. 2009

Environ. Sci. Technol.

206

114

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The photodegradation of the widely used amine drugs including primary amine (mexiletine), secondary amine (propranolol, phenytoin), and tertiary amine (diphenhydramine, antipyrine) were investigated in the presence of nitrate and humic substances under simulated sunlight. All of the amine drugs were photodegraded by nitrate due to the attack of hydroxyl radicals ( • OH). The bimolecular rate constants for the reaction between each amine drug and • OH ranged from (2.1 ( 0.2) × 10 9 to (8.7 ( 0.3) × 10 9 M -1 s -1 . In contrast, only mexiletine, propranolol, and diphenhydramine were selectively photodegraded in the presence of humic substances (HS). Fulvic acid was a more efficient sensitizer than humic acid throughout. The HS triplet states were verified to be main reactive species in the photochemical reaction. Furthermore, an electron transfer mechanism for the reaction with the HS triplet states was proposed on the basis of all information obtained under a series of experiments. The electron transfer from the nonbonding electrons on nitrogen (N-electrons) of the amine drugs to the excited ketone of the HS occurred. The availability of N-electrons and presence of hydrogen on carbon R of amine (R-hydrogen) were two key factors for the electrontransfer interaction. Moreover, the photoproducts were identified by GC-MS and the degradation pathways were proposed. The results strongly suggest the impact of humic substances on the photochemical fate of amine drugs in the natural waters.

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Section: Kinetics Of Photodegradationsupporting

confidence: 84%

Indirect Photodegradation of Amine Drugs in Aqueous Solution under Simulated Sunlight

Chen

et al. 2009

Environ. Sci. Technol.

206

114

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“…Photoinduced electron transfer (PET) is a feasible reaction between ketone or aromatic hydrocarbon photosensitizers and amines [26][27][28][29]. Being a secondary amine, TEMP (E ox = 1.0 V vs SCE) [45] could be oxidized by PET if the process is thermodynamically allowed.…”

Section: Electron Transfer Oxidation Of Temp To Tempomentioning

confidence: 99%

“…Although the TEMPO/EPR method has been largely employed [17][18][19][20][21][22][23][24][25], a systematic investigation of the scope and limitations of this technique has never been performed. For instance, amines are widely known for their quenching ability of excited states, so a probable source of artefacts may be the interaction between the excited photosensitizer and TEMP [26][27][28][29]. The aim of the present study is to compare the results obtained for the detection and quantification of singlet oxygen by means of the direct method (TRNIR emission) and the indirect 1 O 2 trapping mode (TEMPO/EPR method), using a set of well known photosensitizers.…”

Section: Introductionmentioning

confidence: 99%

Scope and limitations of the TEMPO/EPR method for singlet oxygen detection: the misleading role of electron transfer

Nardi

Manet

Monti

et al. 2014

Free Radical Biology and Medicine

215

104

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“…Gupta and Rohatgi-Mukherjee [12] also obtained the same relation for the photooxidation of I -in Me0H-H20 mixed solutions, and proposed a charge-transfer intermediate for the quenching for singlet oxygen by iodide ion. Cohen et al [13] have obtained a linear relation between the log of the quenching rate constant (kq) for triplet benzophenone or fluorenone by amines and 1/e. They proposed the following relation between jOg kq and 1/e; log kq = A GET = IP(D0) -E(Ac-/Ac) -…”

Section: Resultsmentioning

confidence: 99%

Lifetime of Singlet Oxygen and Quenching by NaN₃ in Mixed Solvents

Miyoshi

Ueda

Fuke

et al. 1982

Zeitschrift Für Naturforschung B

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Singlet oxygen was generated by the photosensitization of erythrosine. The lifetime of singlet oxygen and the quenching rate constant for singlet oxygen by NaN3 were measured by a thermal lensing method in MeOH-H2O mixed solvents. The reciprocal of the lifetime increased linearly with the increase of the H2O mole fraction. Semi-log plot of the quenching constant against the reciprocal of the solvent polarity exhibited a linear relation. The quenching of the singlet oxygen by NaN3 may proceed through a partial charge-transfer intermediate. The activation energy for the quenching reaction of N3- + 1O2 →[N3·1O2-] increased with the increase of the solvent polarity. The lifetime was also measured in MeOH-ethyleneglycol mixed solvents, and its relation with viscosity was obtained

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Photoreduction by amines

Cited by 645 publications

References 17 publications

Indirect Photodegradation of Amine Drugs in Aqueous Solution under Simulated Sunlight

Indirect Photodegradation of Amine Drugs in Aqueous Solution under Simulated Sunlight

Scope and limitations of the TEMPO/EPR method for singlet oxygen detection: the misleading role of electron transfer

Lifetime of Singlet Oxygen and Quenching by NaN₃ in Mixed Solvents

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Photoreduction by amines

Cited by 645 publications

References 17 publications

Indirect Photodegradation of Amine Drugs in Aqueous Solution under Simulated Sunlight

Indirect Photodegradation of Amine Drugs in Aqueous Solution under Simulated Sunlight

Scope and limitations of the TEMPO/EPR method for singlet oxygen detection: the misleading role of electron transfer

Lifetime of Singlet Oxygen and Quenching by NaN3 in Mixed Solvents

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Lifetime of Singlet Oxygen and Quenching by NaN₃ in Mixed Solvents