Structure and Reactivity of 3,3‐Disubstituted 1‐(5‐Nitro‐2,1‐benzisothiazol‐3‐yl)triazenes

Abstract

The reaction between 5‐nitro‐2,1‐benzisothiazole‐3‐diazonium species and N‐substituted anilines produces the 1‐(5‐nitro‐2,1‐benzisothiazol‐3‐yl)‐3,3‐disubstituted triazenes 1. These triazenes are highly stable, and even in strongly acidic medium (0.5 mol⋅L−1 H2SO4) they are only slowly decomposed back to the diazonium ion and substituted anilinium ion (for the N‐ethyl derivative in 0.5 mol·L−1 H2SO4 at 25 °C, t1/2 ≈︁ 7 h). A series of six triazenes were characterised by their 1H and 13C NMR spectra and mass spectra. Two of the triazenes were also identified by X‐ray crystallography. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Structure of azo coupling products of 5-nitro-2,1-benzisothiazole-3-diazonium hydrogensulphate with aromatic amines

“…The way of preparation and the properties of triazenes 1aef (R 1 ¼ CH 3 , R 2 ¼ H; R 1 ¼ C 2 H 5 , R 2 ¼ H; R 1 ¼ C 6 H 5 , R 2 ¼ H; R 1 ¼ n-C 4 H 9 , R 2 ¼ H; R 1 ¼ n-C 4 H 9 , R 2 ¼ CH 3 ; R 1 ¼ CH 2 CH 2 CN, R 2 ¼ CH 3 ; R 1 ¼ CH 2 CH 2 OH, R 2 ¼ Cl) were published in our earlier paper [1]. The above-given triazenes were characterised by elemental analysis, 1 H and 13 C NMR spectra and APCI mass spectra.…”

“…The above-given triazenes were characterised by elemental analysis, 1 H and 13 C NMR spectra and APCI mass spectra. In three cases, X-ray structural analyses were also carried out with R 1 ¼ C 6 H 5 , R 2 ¼ H and R 1 ¼ CH 2 CH 2 OH, R 2 ¼ Cl [1] and with R 1 ¼ n-C 4 H 9 , R 2 ¼ H [2]. The triazenes are brilliant orange substances with l max w 460 nm and 3 max w 2.5 Â 10 4 l mol ÿ1 cm ÿ1 .…”

“…They are surprisingly stable in acid media in contrast to the 1,3-diaryltriazenes so far known, which are rapidly split in acid medium to give the diazonium ion and amine [3e5]. We have found out that 1-(5-nitro-2,1-benzisothiazol-3-yl)-3-ethyl-3-phenyltriazene is decomposed in 0.5 mol l ÿ1 H 2 SO 4 in aqueous acetic acid (1:1 v/v) at 25 C to give 5-nitro-2, 1-benzisothiazole-3-diazonium with a half-life t 1/2 ¼ 417 min [1]. We ascribe the high stability of triazenes 1 to the different sites of protonation of these substances, as compared with 1, 3-diaryltriazenes.…”

“…We ascribe the high stability of triazenes 1 to the different sites of protonation of these substances, as compared with 1, 3-diaryltriazenes. While 1,3-diaryltriazenes are protonated at the NH group of triazene grouping, triazenes 1 are presumably protonated at the heterocyclic nitrogen [1].…”

Effects of Micellar Aggregates on the Kinetics and Mechanism of the Reaction between 4‐Nitrobenzenediazonium Ions and Some Amino Acids

“…Triazenes are also important in organic chemistry [21] because they have been (and still are) used as protecting groups in natural-product synthesis [22] and combinatorial chemistry [22], and they have been incorporated into polymer [23] and oligomer [24] synthesis and used to form novel heterocycles [25]. Tracey and Shuker [26] characterized azo coupling adducts of benzenediazonium ions with aromatic peptides and proteins, and Patt and Patt [27] studied the reaction of 4-[ A literature survey indicates that there are not many kinetic studies on the reaction of arenediazonium ions with amino acids or proteins in aqueous solution [15 -17] [28]. Most of the kinetic studies have been carried out in alkaline solution, and contradictory reports appeared.…”