排序方式: 共有11条查询结果,搜索用时 703 毫秒
1.
2.
Chauzov V. A. Parchinskii V. Z. Sinel"shchikova E. V. Burasov A. V. Ugrak B. I. Parfenov N. N. Petrosyan V. A. 《Russian Chemical Bulletin》2002,51(8):1523-1532
The reactions of 1,4-dimethoxybenzene with 4-nitropyrazole, 3,4-dinitro-5-methylpyrazole, 1,2,4-triazole, 3-nitro-1,2,4-triazole, and tetrazole were studied during undivided amperostatic electrolysis on a Pt electrode in MeCN, CH2Cl2, and MeOH. The main reaction products were 2-azolyl-1,4-dimethoxybenzenes and (or) 1,4-diazolyl-1,4-dimethoxycyclohexa-2,5-dienes. In all cases except 1,2,4-triazole, N-arylation occurs only in the presence of the Alk4N+ salts of azoles or 2,4,6-trimethylpyridine as a base. The mechanism of the reactions is discussed. 相似文献
3.
Electrochemical acetoxylation of 1,4-dimethoxybenzene during amperostatic electrolysis in an undivided cell at Pt electrodes
in MeCN or MeOH solutions containing Et4NOAc gives 2,5-dimethoxyphenyl acetate if AcOH or CH2Cl2 co-solvent has been added in a concentration of ≥50%. The reaction mechanism includes a nucleophilic attack of AcO− ion on the ipso-position of 1,4-dimethoxybenzene radical cation. The process efficiency depends on factors that determine the stability and
reactivity of the intermediate 1,4-dimethoxy-1-acetoxyarenonium cation.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1534–1538, July, 2005. 相似文献
4.
The influence of the acid components of the medium on the anodic 2,5-dimethoxy-phenylation of various azoles at the nitrogen atom was studied for constant-current electrolysis of the mixture azole—1,4-dimethoxybenzene in an undivided cell. Elimination of azole functions in the key steps of the process can be catalyzed by such electrophilic species as Brønsted (AcOH) and Lewis acids (ZnCl2) and even the radical cation generated in the anodic oxidation of 1,4-dimethoxybenzene. The data obtained provided evidence for the existence of the arenonium cation as a key reaction intermediate. 相似文献
5.
Electrochemical azolation of 1,2-and 1,3-dimethoxybenzenes with tetrazole, pyrazole and triazole derivatives in MeCN in an
undivided cell with Pt electrodes proceeds through the formation of intermediate arenonium cations of the ipso-structure. Nature of the starting arenes and the corresponding intermediate arenonium cations determine composition and yields
of the target products. 相似文献
6.
7.
Data on the effect of the acid-base properties of the medium on the yield and composition of the products of N-dimethoxyphenylation of azoles (pyrazole, triazole, their substituted derivatives, and tetrazole) upon galvanostatic electrolysis
of azole—1,4-dimethoxybenzene mixtures in nucleophilic (MeOH) and neutral (MeCN) media were considered and the trends of this
process were discussed. The generation of arenium cations (1,4-dimethoxy-1-azolylbenzenium in MeCN and 1,1,4-trimethoxybenzenium
in MeOH) as the key intermediates of electrosynthesis of N-(dimethoxyphenyl)azoles, was proved experimentally. A new approach to the synthesis of N-(dimethoxyphenyl)azoles through electrosynthesis of 1,1,4,4-tetramethoxycyclohexa-2,5-diene by electrooxidation of 1,4-dimethoxybenzene
in MeOH as the first step and the reaction of this quinone diketal with azoles as the second step was suggested. The efficiency
of this route to N-(dimethoxyphenyl)azoles is comparable with the efficiency of the purely electrochemical one-step process.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2101–2109, November, 2007. 相似文献
8.
9.
The reactions of 1,4-dimethoxybenzene with azoles (pyrazole, triazole, and their derivatives, as well as tetrazole) were studied
by undivided amperostatic electrolysis at Pt electrodes in MeOH. The process proceeds via the formation of a 1,1,4-trimethoxyarenonium cation as the key intermediate and affords 1,1,4,4-tetramethoxycyclohexa-2,5-diene,
1,1,4-trimethoxy-4-(azol-1-yl)cyclohexa-2,5-diene, and 1,4-dimethoxy-2-(azol-1-yl)benzene as the main products. Azole and
solvent molecules compete as nucleophiles during electrolysis. A fine mechanism of the process was considered.
Dedicated to Academician N. K. Kochetkov on the occasion of his 90th birthday.
__________
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1166–1171, May, 2005. 相似文献
10.
A. V. Burasov T. S. Vakhotina V. A. Petrosyan 《Russian Journal of Electrochemistry》2005,41(8):903-907
Using the obtaining of 1,4-dimethoxy-2-(3-nitro-1,2,4-triazole-1-yl)benzene (I) and 1,4-dimethoxy-2-(tetrazolyl-1+-2)benzene (II) as an example, a method for indirect electrosynthesis of these substances is developed. In the first stage of this process, electrosynthesis of 1,1,4,4-tetramethoxycyclohexane-2,5-diene is realized by means of oxidation of 1,4-dimethoxybenezene on a platinum anode in an environment of MeOH in a diaphragmless cell. In the second, chemical interaction of this diene with 3-nitro-1,2,4-triazole and tetrazole is performed when heating a mixture of these substances for a long time at 110°C in the presence of additives of collidine. As a result, target products I and II were obtained with a good (60–90%) yield. Realization of this process opens new possibilities for producing N-arylazoles.__________Translated from Elektrokhimiya, Vol. 41, No. 8, 2005, pp. 1014–1019.Original Russian Text Copyright © 2005 by Burasov, Vakhotina, Petrosyan. 相似文献