Nucleophilic substitution of the nitro group in 1-substituted 3-nitro-1 H -1,2,4-triazoles in ethanolic potassium hydrox
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Nucleophilic substitution of the nitro group in 1-substituted 3-nitro-1H-1,2,4-triazoles in ethanolic potassium hydroxide Ani H. Hasratyan1*, Astkhik А. Sukoyan1, Aleksan G. Shakhatuni2, Gevorg G. Danagulyan1,3, Hovhannes S. Attaryan1,3 1
Institute of Organic Chemistry of Scientific–Technological Center of Organic and Pharmaceutical Chemistry, National Academy of Sciences of the Republic of Armenia, 26 Azatutyan Ave., Yerevan 0014, Armenia; e-mail: [email protected] 2 Molecular Structure Research Center of Scientific–Technological Center of Organic and Pharmaceutical Chemistry, National Academy of Sciences of the Republic of Armenia, 26 Azatutyan Ave., Yerevan 0014, Armenia; e-mail: [email protected] 3 Russian-Armenian University, 123 Hovsep Emin St., Yerevan 0051, Armenia; e-mail: [email protected] Translated from Khimiya Geterotsiklicheskikh Soedinenii, 2020, 56(8), 1100–1102
Submitted March 5, 2020 Accepted after revision May 14, 2020
Dehydrochlorination of 1-(2-chloroethyl)-3-nitro-1H-1,2,4-triazole in ethanolic potassium hydroxide is accompanied by nucleophilic substitution of the nitro group by the ethoxy group. The same nucleophilic exchange in 1-substituted 3-nitro-1H-1,2,4-triazoles occurs in methanol and n-propanol solutions of potassium hydroxide. Keywords: 1,2,4-triazole, dehydrochlorination, ethanolic solutions, nitro group, nucleophilic substitution.
1-(2-Haloethyl)-3-nitro-1H-1,2,4-triazoles, alkylation products of 3-nitro-1H-1,2,4-triazole, are intermediates in the synthesis of 3-nitro-1-vinyl-1H-1,2,4-triazole, which is considered an important reagent for the creation of highperformance components of explosives and propellants.1,2 In our recent communication,3 we proposed a new medium, 50% aqueous N-methylmorpholine N-oxide (NMO) in the presence of alkali (NaOH), for the alkylation of 3-nitro-1H-1,2,4-triazole with 1,2-dibromoethane. This communication is devoted to the study of the alkylation of 3-nitro-1H-1,2,4-triazole (1) with 1,2-dichloroethane in a similar system (KOH as alkali). However, it was found that under the selected conditions, the alkylation of triazole 1 with 1,2-dichloroethane does not occur. We modified the conditions and studied the alkylation process in anhydrous NMO solution, which led to the formation of 1-(2-chloroethyl)-3-nitro-1H-1,2,4-triazole (2) in 67% yield (Scheme 1). Further, in order to obtain 3-nitro-1-vinyl-1H-1,2,4triazole (3), dehydrochlorination of compound 2 in ethanolic KOH solution was carried out (Scheme 2). 0009-3122/20/56(8)-1100©2020 Springer Science+Business Media, LLC
Scheme 1 NO2
N N H
N 1
Scheme 2
1100
Cl
Cl
KOH, 65–70°C, 6 h 67%
NMO, H2O NMO
N N
NO2 N Cl 2
Chemistry of Heterocyclic Compounds 2020, 56(8), 1100–1102
However, according to the 1H and 13C NMR spectroscopy data, it was found that a mixture of two products, namely, triazoles 4 and 5, had been isolated instead of the expected 3-nitro-1-vinyl-1,2,4-triazole (3). In fact, the process of triazole 2 dehydrochlorination with potassium hydroxide in EtOH is accompanied by n
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