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.

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 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.

Sintesis dan Karakterisasi Na-CMC dari A-Selulosa Serabut Kelapa Sawit

2021 ◽  
Vol 1 (9) ◽  
pp. 375-381
Author(s):  
Indriani Indriani ◽  
Abu Hasan ◽  
Anerasari Meydinariasty
Keyword(s):  
Palm Oil ◽  
Trichloroacetic Acid ◽  
Reaction Medium ◽  
Synthesis Process ◽  
Optimal Composition ◽  
Palm Fiber ◽  
Oil Processing ◽  
Reaction Media ◽  
By Products

Na-CMC adalah eter polimer selulosa linier yang digunakan sebagai bahan pengental, pengemulsi dan penstabil. Salah satu bahan dasar pembuatan Na-CMC yaitu serabut kelapa sawit. Serabut kelapa sawit merupakan salah satu hasil samping terbesar yang dihasilkan dalam proses pengolahan minyak kelapa sawit dan dapat dapat dijadikan sebagai sumber selulosa karena mengandung selulosa hingga 59,60%. Tujuan dari penelitian ini untuk mendaptakan komposisi optimal campuran media reaksi isopropanol-etanol dan konsentrasi asam trikloroasetat serta konsentrasi NaOH dengan memvariasikan komposisi media reaksi isopropanol-etanol menjadi 20:80; 40:60; 50:50; 60:40 dan 80:20, sedangkan untuk konsentrasi asam trikloroasetat yaitu 15%, 20% san 25% dan untuk konsentrasi NaOH adlah 15% dan 20%. Didapat bahwa  komposisi optimal media reaksi pada proses sintesis Na-CMC terdapat pada campuran isopropanol-etanol 80:20 dengan konsentrasi asam trikloroasetat 25% dan konsentrasi NaOH 20% menghasilkan nilai DS yang tertinggi yaitu sebesar 0,8124 dengan kemurnian dan pH berturut-turut sebesar 99,68% dan 7,9.   Na-CMC is a linear cellulose polymer ether used as a thickener, emulsifier and stabilizer. One of the basic ingredients for making Na-CMC is palm fiber. Palm fiber is one of the largest by-products produced in the palm oil processing process and can be used as a source of cellulose because it contains up to 59.60% cellulose. The purpose of this study was to obtain the optimal composition of the isopropanol-ethanol reaction media mixture and the concentration of trichloroacetic acid and NaOH concentration by varying the composition of the isopropanol-ethanol reaction medium to 20:80; 40:60; 50:50; 60:40 and 80:20, while the concentrations of trichloroacetic acid were 15%, 20% and 25% and the concentrations of NaOH were 15% and 20%, respectively. It was found that the optimal composition of the reaction medium in the Na-CMC synthesis process was found in a mixture of isopropanol-ethanol 80:20 with a concentration of 25% trichloroacetic acid and 20% NaOH concentration resulting in the highest DS value of 0.8124 with purity and pH respectively. 99.68% and 7.9.

Wavelength controlled production of SO4- radicals in the ultraviolet photolysis of ceric sulfate solutions

1984 ◽  
Vol 37 (3) ◽  
pp. 475 ◽  
Author(s):  
RW Matthews
Keyword(s):  
Rate Constants ◽  
Photochemical Reaction ◽  
Transfer Reaction ◽  
Quantum Yields ◽  
Oh Radical ◽  
Transfer Energy ◽  
Fluorescence Measurements ◽  
Sulfate Solutions ◽  
Ultraviolet Photolysis ◽  
Primary Photochemical Reaction

Solutions of cerium(III)/(IV) and formic acid in 0.4 M sulfuric acid have been photolysed under 254 nm and 365 nm light. Marked differences in the reaction kinetics and quantum yields are observed at the two different wavelengths. At 365 nm, the reactions leading to cerium(IV) reduction are caused almost exclusively by the SO4- radical. The ratio of rate constants, k(SO4- + CeIII)/ k(SO4- + HCOOH), is 116 � 11 and the quantum yield of sulfate radicals, ф(SO4-), is 0.023 � 0.002. At 254 nm, the reactions leading to cerium(IV) reduction are caused mainly by the OH radical, but approximately 35% of the oxidizing radicals formed in the primary photochemical reaction are SO4-. Cerium(III) species, excited at 254 nm, transfer energy to cerium(IV) and this results in an additional yield of OH and SO4- radicals. Fluorescence measurements confirmed the efficiency of the energy transfer reaction. The ratio of rate constants, k(OH+CeIII)/k(OH+HCOOH), is 2.22 � 0.18 and ф(CeIV*) and ф(CelIII*) giving oxidizing radicals are 0.116 � 0.010 and 0.0083 � 0.0008 respectively. Thus about 5 times more total oxidizing radicals are produced from excited cerium(IV) species at 254 nm than at 365 nm.

scholarly journals Phase-Selective Microwave Assisted Synthesis of Iron(III) Aminoterephthalate MOFs

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1469 ◽  
Author(s):  
Ana Arenas-Vivo ◽  
David Avila ◽  
Patricia Horcajada
Keyword(s):  
Reaction Medium ◽  
Microwave Assisted Synthesis ◽  
X Ray Diffraction ◽  
Synthetic Strategy ◽  
Transmission Electron ◽  
Metal Organic ◽  
High Space ◽  
Pure Phases ◽  
The Impact ◽  
Reaction Media

Iron(III) aminoterephthalate Metal-Organic Frameworks (Fe-BDC-NH2 MOFs) have been demonstrated to show potential for relevant industrial and societal applications (i.e., catalysis, drug delivery, gas sorption). Nevertheless, further analysis is required in order to achieve their commercial production. In this work, a systematic synthetic strategy has been followed, carrying out microwave (MW) assisted hydro/solvothermal reactions to rapidly evaluate the influence of different reaction parameters (e.g., time, temperature, concentration, reaction media) on the formation of the benchmarked MIL-101-NH2, MIL-88B-NH2, MIL-53-NH2 and MIL-68-NH2 solids. Characterization of the obtained solids by powder X-ray diffraction, dynamic light scattering and transmission electron microscopy allowed us to identify trends to the contribution of the evaluated parameters, such as the relevance of the concentration of precursors and the impact of the reaction medium on phase crystallization. Furthermore, we presented here for the first time the MW assisted synthesis of MIL-53-NH2 in water. In addition, pure MIL-101-NH2 was also produced in water while MIL-88-NH2 was the predominant phase obtained in ethanol. Pure phases were produced with high space-time yields, unveiling the potential of MW synthesis for MOF industrialization.

Time-resolved study of the photochemical reaction of 4-dimethylaminobenzonitrile with carbon tetrachloride

2001 ◽  
Vol 32 (2) ◽  
pp. 115-123 ◽  
Author(s):  
C. Ma ◽  
W. M. Kwok ◽  
P. Matousek ◽  
A. W. Parker ◽  
D. Phillips ◽  
...  
Keyword(s):  
Carbon Tetrachloride ◽  
Photochemical Reaction ◽  
Time Resolved
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