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2‐Alkyl‐1,2,3,4‐benzotetrazinium Salts: Synthesis and NMR Studies of the Novel 2‐Alkyl‐1,2,3,4‐tetrazinium/ ortho ‐(Alkylazo)diazonium Equilibrium
Author(s) -
Lipilin Dmitry L.,
Belyakov Pavel A.,
Strelenko Yuri A.,
Churakov Aleksandr M.,
Smirnov Oleg Yu.,
Ioffe Sema L.,
Tartakovsky Vladimir A.
Publication year - 2002
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/1099-0690(200211)2002:22<3821::aid-ejoc3821>3.0.co;2-y
Subject(s) - chemistry , alkyl , carbon 13 nmr , proton nmr , salt (chemistry) , ring (chemistry) , nmr spectra database , medicinal chemistry , nuclear magnetic resonance spectroscopy , chemical shift , stereochemistry , organic chemistry , spectral line , physics , astronomy
The diazotization of anilines bearing the ortho ‐alkylazo group resulted in benzenediazonium salts 3 , which exist in equilibrium with the 2‐alkyl‐1,2,3,4‐benzotetrazinium salt cyclic isomers 4 . The structures of 3 and 4 were confirmed by 1 H, 13 C, and 15 N NMR studies. The relative proportions of the cyclic and open‐chain forms were determined by a 1 H NMR study. The 3 ⇄ 4 equilibrium is fast on the NMR timescale, and only one set of signals is observed in the 1 H and 13 C NMR spectra. The equilibrium strongly depends on the substituents on the aromatic ring, while being practically unaffected by the substituents (methyl or tert ‐butyl) on the azo group. Some of the investigated salts exist only in the cyclic form ( 4f , 4g ), others only in the open‐chain form ( 3k ). (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)