One-electron photooxidation of carbazole in the presence of carbon tetrachloride. Part I. Carbon tetrachloride and ethanol used as reaction media

1982 ◽  
Vol 60 (8) ◽  
pp. 945-956 ◽  
Author(s):  
Bogumil Zelent ◽  
Gilles Durocher
Keyword(s):  
Electron Transfer ◽  
Carbon Tetrachloride ◽  
Photochemical Reaction ◽  
Ethanol Solution ◽  
Photochemical Reactions ◽  
Reaction Products ◽  
Solvent Cage ◽  
Ct Complex ◽  
Heterolytic Dissociation ◽  
Reaction Media

The photochemical reaction products of carbazole with carbon tetrachloride in ethanol have been isolated and identified along with photoproducts in the irradiated solution of carbazole in pure CCl4 using water and ethanol added after the irradiation. This allowed us to discuss the complex mechanism of secondary photochemical changes in the carbazole–CCl4 system. We propose that the electron transfer from carbazole to CCl4 molecule in the excited CT complex, [Formula: see text] is the primary photochemical reaction followed by an heterolytic dissociation of a C—Cl bond which gives rise to the primary photoproducts in the solvent cage [C+•Cl−ĊCl3]. Secondary photochemical reactions initiate transformation of the radical cation of carbazole in the solvent cage giving rise to the following intermediate species:[Formula: see text]The probability of formation and further transformations of these Transient products: α, β, and γi, depends strongly on the nature of the reaction media. Thermodynamically stable products are formed depending on the reaction media; (carboethoxy)carbazoles, (carbo-N-carbazyl)carbazoles, and carbazole – carboxylic acids can serve as a proof for the formation of the above listed intermediates. All the results reported on the secondary photochemical reactions strongly support the electron-transfer primary mechanism used to explain the fluorescence quenching of carbazole by CCl4.These results also explain the changes observed in the fluorescence spectrum of carbazole when the ethanol solution of carbazole in the presence of CCl4 is irradiated.

One-electron photooxidation of N-ethylcarbazole in the presence of carbon tetrachloride. Products and mechanism of the photochemical reaction

1985 ◽  
Vol 63 (7) ◽  
pp. 1654-1665 ◽  
Author(s):  
Bogumil Zelent ◽  
Gilles Durocher
Keyword(s):  
Carbon Tetrachloride ◽  
Photochemical Reaction ◽  
Reaction Medium ◽  
Chloride Ion ◽  
Photochemical Reactions ◽  
The Other ◽  
Main Process ◽  
Reaction Products ◽  
Solvent Cage ◽  
Ct Complex

The mechanism of the photodecomposition of N-ethylcarbazole (NEC) in the presence of carbon tetrachloride has been discussed on the basis of the photoproducts identified. The photodissociation of the N-ethyl bond and the electron transfer in the transiently formed ex-CT complex, [Formula: see text], have been proposed as the primary photochemical processes involved irr the singlet excited NEC molecule. The latter, treated as the main process, leads to the radical cation of NEC, chloride ion, and trichloromethyl radical in the solvent cage, [NEC+•Cl−ĊCl3]. The other reactions in the system studied are analysed following the decomposition of NEC+• in the presence of Cl− and ĊCl3, which can occur by the N-ethyl group and (or) by the aromatic ring. The formation of intermediate products such as[Formula: see text]in the solvent cage gives rise to secondary photochemical reactions in the system studied. The polarity and chemical activity of the reaction media used strongly influence the nature of the secondary photochemical transformations both in and outside the solvent cage. The formation mechanism of the photochemical reaction products in CCl4 when ammonia was used, after and during irradiation, has been explained mainly by the transformations of the radical αr and cation αk as well as by the carbazyl radical β, which is also formed in the reaction medium. On the other hand, reaction of the cation [Formula: see text] explains the formation of the photoproducts in the irradiated solution of NEC with CCl4 in ethanol. These photochemical results have been compared to the photochemical reactions involved in the carbazole–CCl4 system.

One-electron photooxidation of carbazole in the presence of carbon tetrachloride. Part II. Carbon tetrachloride as a reaction medium. Use of ammonia after irradiation and during irradiation

1982 ◽  
Vol 60 (19) ◽  
pp. 2442-2450 ◽  
Author(s):  
Bogumil Zelent ◽  
Gilles Durocher
Keyword(s):  
Carbon Tetrachloride ◽  
Photochemical Reaction ◽  
Reaction Medium ◽  
Radical Cations ◽  
Mechanism Of Formation ◽  
Ammonia Gas ◽  
Solvent Cage ◽  
Determining Factors ◽  
Primary Photochemical Reaction ◽  
Reaction Media

In part I of this series of papers we proposed the mechanism of electron transfer as the primary photochemical reaction in the carbazole – carbon tetrachloride system along with a secondary photochemical reaction initiated by transformations of the radical cation of carbazole in the solvent cage resulting in intermediates:[Formula: see text]In this paper we discuss the influence of ammonia, used after and during irradiation, on the mechanism of secondary transformation and the formation of thermodynamically stable products in the system studied. Such compounds as N-cyanocarbazole, 1-cyanocarbazole, and 3-cyanocarbazole have been formed as the main products during neutralization of the photolyte solution by ammonia gas. The mechanism of formation of these compounds has been explained by the chemical reaction of ammonia with cations α and γi. If ammonia is present in the solution of carbazole in CCl4 during irradiation, such products as N,N′-dicarbazyl and N-cyanocarbazole are mainly formed along with 3-(N-carbazyl)carbazole, 3,9-di-(N-carbazyl)carbazole, and N-cyano-3-(N-carbazyl)carbazole. In such a case, reactions of radicals β are the determining factors in the secondary photochemical transformations. Radicals β are formed by the reaction involving ammonia with radical cations of carbazole. All the results in this paper have been discussed taking under consideration the influence of the reaction media on the mechanism of photochemical transformation of carbazole.

Photochemical Reactions of Bromoanthracenes with N,N-Dimethylaniline in Solution

1981 ◽  
Vol 36 (7) ◽  
pp. 846-851 ◽  
Author(s):  
Jan Fulara ◽  
Tadeusz Latowski
Keyword(s):  
Photochemical Reaction ◽  
Photochemical Reactions ◽  
Medium Effect ◽  
Reaction Products ◽  
Photochemical Transformations

AbstractMajor products of the photolysis of 9-bromoanthracene and 9,10-dibromoanthracene in benzene and acetonitrile as well as photochemical reaction products of the two bromoanthracenes with N,N-dimethylaniline in these solvents have been isolated and identified. The mechanisms of partial reactions are discussed and attention is paid to the medium effect on the photochemical transformations.

Mutagenicity assays of photochemical reaction products of biphenyl (BP) and o-phenylphenol (OPP) with NOx

Chemosphere ◽  
1981 ◽  
Vol 10 (2) ◽  
pp. 223-228 ◽  
Author(s):  
Teruhisa Hirayama ◽  
Motoshi Nohara ◽  
Hirohiko Shindo ◽  
Shozo Fukui
Keyword(s):  
Photochemical Reaction ◽  
Reaction Products

scholarly journals Spectroscopic evidence for direct flavin-flavin contact in a bifurcating electron transfer flavoprotein

2020 ◽  
Vol 295 (36) ◽  
pp. 12618-12634
Author(s):  
H. Diessel Duan ◽  
Nishya Mohamed-Raseek ◽  
Anne-Frances Miller
Keyword(s):  
Electron Transfer ◽  
Density Functional ◽  
Protein Denaturation ◽  
Rhodopseudomonas Palustris ◽  
Density Functional Theory Calculations ◽  
Site Directed Mutagenesis ◽  
Functional Theory ◽  
Electron Transfer Flavoprotein ◽  
Midpoint Potential ◽  
Ct Complex

A remarkable charge transfer (CT) band is described in the bifurcating electron transfer flavoprotein (Bf-ETF) from Rhodopseudomonas palustris (RpaETF). RpaETF contains two FADs that play contrasting roles in electron bifurcation. The Bf-FAD accepts electrons pairwise from NADH, directs one to a lower-reduction midpoint potential (E°) carrier, and the other to the higher-E° electron transfer FAD (ET-FAD). Previous work noted that a CT band at 726 nm formed when ET-FAD was reduced and Bf-FAD was oxidized, suggesting that both flavins participate. However, existing crystal structures place them too far apart to interact directly. We present biochemical experiments addressing this conundrum and elucidating the nature of this CT species. We observed that RpaETF missing either FAD lacked the 726 nm band. Site-directed mutagenesis near either FAD produced altered yields of the CT species, supporting involvement of both flavins. The residue substitutions did not alter the absorption maximum of the signal, ruling out contributions from residue orbitals. Instead, we propose that the residue identities modulate the population of a protein conformation that brings the ET-flavin and Bf-flavin into direct contact, explaining the 726 nm band based on a CT complex of reduced ET-FAD and oxidized Bf-FAD. This is corroborated by persistence of the 726 nm species during gentle protein denaturation and simple density functional theory calculations of flavin dimers. Although such a CT complex has been demonstrated for free flavins, this is the first observation of such, to our knowledge, in an enzyme. Thus, Bf-ETFs may optimize electron transfer efficiency by enabling direct flavin-flavin contact.

Mutagenicity of coal-pyrolyzed products and their photochemical reaction products with nitrogen oxides in Salmonella typhimurium TA98 and TA100

1983 ◽  
Vol 122 (3-4) ◽  
pp. 273-278 ◽  
Author(s):  
Teruhisa Hirayama ◽  
Motoshi Nohara ◽  
Takayasu Ando ◽  
Masaru Tanaka ◽  
Kimiko ◽  
...  
Keyword(s):  
Nitrogen Oxides ◽  
Salmonella Typhimurium ◽  
Photochemical Reaction ◽  
Reaction Products

Photochemical Reaction of Mo(CO)6with Et2GeH2: NMR and DFT Studies of Reaction Products; Crystal Structure of a Novel Complex [{Mo(μ-η2-H−GeEt2)(CO)4}2]

2009 ◽  
Vol 28 (20) ◽  
pp. 5857-5865 ◽  
Author(s):  
Magdalena Zyder ◽  
Andrzej Kochel ◽  
Jarosław Handzlik ◽  
Teresa Szymańska-Buzar
Keyword(s):  
Crystal Structure ◽  
Photochemical Reaction ◽  
Dft Studies ◽  
Reaction Products ◽  
Novel Complex

Photochemical reactions of azo compounds. IX. Further studies related to the photochemical reactions of bisazo compounds

1967 ◽  
Vol 20 (2) ◽  
pp. 321 ◽  
Author(s):  
NC Jamieson ◽  
GE Lewis
Keyword(s):  
Sulphuric Acid ◽  
Photochemical Reaction ◽  
Photochemical Reactions ◽  
Azo Compounds ◽  
Bisazo Compounds ◽  
First Time

The photochemical reactions of 4,4?-bis(phenylazo)biphenyl and 4- phenyl-azoazobenzene in 98% sulphuric acid have been examined, for comparison with the corresponding reactions in 22N acid. Photochemical cyclodehydrogenation of 4-phenylazoazobenzene to two benzo[c]cinnoline derivatives has thereby been effected for the first time. The observed course of the latter reaction has led, in turn, to studies of the benzidine rearrangement of 2-(2-phenylhydrazino)benzo[c]- cinnoline, of the photochemical cyclodehydrogenation of 3-phenylazobenzene, and of the photochemical reaction of 2-phenylazobenzo[c]cinnoline. The results of these investigations are now recorded and discussed.

LED Light Sources in Organic Synthesis: An Entry to A Novel Approach

2021 ◽  
Vol 18 ◽  
Author(s):  
Aparna Das
Keyword(s):  
Organic Compounds ◽  
Organic Synthesis ◽  
Photochemical Reaction ◽  
Low Cost ◽  
Environmentally Friendly ◽  
Photochemical Reactions ◽  
Light Sources ◽  
Blue Led ◽  
Oxidation Reduction ◽  
Novel Approach

: In recent years, photocatalytic technology has shown great potential as a low-cost, environmentally friendly, and sustainable technology. Compared to other light sources in photochemical reaction, LEDs have advantages in terms of efficiency, power, compatibility, and environmentally-friendly nature. This review highlights the most recent advances in LED-induced photochemical reactions. The effect of white and blue LEDs in reactions such as oxidation, reduction, cycloaddition, isomerization, and sensitization is discussed in detail. No other reviews have been published on the importance of white and blue LED sources in the photocatalysis of organic compounds. Considering all the facts, this review is highly significant and timely.

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