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Paper | Regular issue | Vol 55, No. 1, 2001, pp.127-133
Published online, 1st January, 1970
DOI: 10.3987/COM-00-9070
1H- and 13C-NMR Investigations on σ-Adduct Formation of 1,2,4-Triazine 4-Oxides and 3-Chloro-6-phenyl-1,2,4-triazine with Liquid Ammonia and Alkylamines

Andrzej Rykowski,* Oleg N. Chupakhin, Dmitry N. Kozhevnikov, Valery N.Kozhevnikov, Vladimir L. Rusinov, and Henk C. Van der Plas

*Institute of Chemistry, University of Podlasie, ul. 3-go Maja 54, 08-110 Siedlce, Poland

Abstract

1H- and 13C-NMR spectra of the σ-adducts formed between 6-phenyl-1,2,4-triazine 4-oxide (1a), 3-ethyl-6-phenyl-1,2,4-triazine 4-oxide (1b) and liquid ammonia, methylamine or dimethylamine are described, together with 1H NMR spectra of 3-chloro-6-phenyl-1,2,4-triazine (7) in liquid ammonia. The results of the NMR study have shown that the carbon C-5 in 1a-b and 7 is the preferred site for nucleophilic attack by liquid ammonia and alkylamines at low temperatures (from -75° to -20°C). The s-adduct (5e) formed between 1a and dimethylamine at -75°C on heating to -20°C irreversibly converts to open-chain product (3a), via intermediary C-3 σ-adduct (6). The amination of 7 into 3-amino-6-phenyl-1,2,4-triazine (10) occurs via SN(AE) mechanism involving the isomerisation of the C-5 σ-adduct (8) into the C-3 σ-adduct (9) as confirmed by a 15N study with labeled liquid ammonia.