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Triazene

About: Triazene is a research topic. Over the lifetime, 759 publications have been published within this topic receiving 8714 citations. The topic is also known as: Triazene cleavage & 1-triazene.


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Journal ArticleDOI
TL;DR: In this paper, the authors describe acid-catalysed deacylation of 1-aryl-3-acyl-3methyltriazenes in aqueous sulfuric acid.
Abstract: The hydrolysis of 1-aryl-3-acyl-3-methyltriazenes in aqueous sulfuric acid is described. The 3-formyl derivative undergoes an acid-catalysed deacylation reaction, characterised by a monotonic rise in the pseudo-first-order rate constant, k0 with increasing acidity, solvent deuterium isotope effects, kH2SO4/kD2SO4, of 0.9 (at 0.95 mol dm–3 H2SO4) and 0.8 (at 2.85 mol dm–3 H2SO4) and an entropy of activation of –80 J mol–1 K–1. The 3-alkanoyl derivatives also undergo acid-catalysed decomposition involving cleavage of either the N3–C acyl bond or the N2–N3 triazene bond. Below 3 mol dm–3 H2SO4, only acyl bond cleavage is observed. At higher acidities the extent of N2–N3 bond cleavage increases. The reaction is characterised by (i) solvent deuterium isotope effects of ca. 0.6 at 2 and 5 mol dm–3 H2SO4 and ca. 0.4 at 8 mol dm–3 H2SO4, (ii)ΔS‡ values of –6.7 and –51 J mol–1 K–1 at 2 and 6.1 mol dm–3 H2SO4, respectively, (iii) Hammett ρ values for the substituent in the triazene N-aryl ring of –0.7 and –0.9 at 3 and 9 mol dm–3 H2SO4, respectively, and (iv) an increase in reactivity with electron donating ability of the alkyl substituent of the acyl group. The 3-trifluoroacetyl triazenes are subject to solvolysis of the neutral, as well as the protonated, substrate. The hydrolysis of the neutral substrate involves N–acyl bond cleavage and is characterised by a solvent deuterium isotope effect, kH2O/kD2O, of 2.4, and a Hammett ρ value of +0.8 for the substituent in the N-aryl ring. The reactivity of the neutral substrate diminishes with increasing acidity until 6 mol dm–3 H2SO4, beyond which acid-catalysed N–acyl bond cleavage predominates, for which the solvent isotope effect, kH2SO4/kD2SO4, is 0.8 and the Hammett ρ value –0.5. The 3-aroyl substrates suffer acid-catalysed decomposition, the extent of the N2–N3 bond cleavage process being greater than for the N-alkanoyl counterparts. The reactions are rationalised in terms of a process that involves pre-equilibrium protonation of the substrate either at the N1 triazene atom or the amide oxygen atom, followed by subsequent decomposition of the protonated substrate via either N3–C bond cleavage, involving attack of water at the amide carbonyl, or unimolecular N2–N3 bond cleavage. The relative extents of the N3–C and N2–N3 bond cleavage processes depend on the reactivity of the acyl group and the water activity; the higher the water activity and the more reactive the acyl group, the more deacylation is favoured.

6 citations

Journal ArticleDOI
TL;DR: The reaction of iodo- or bromo-substituted aryltriazenes with i-PrMgCl·LiCl generates the corresponding magnesiated derivatives which react with various electrophiles (acid chlorides, 3-iodoenones, allylic halides, aldehydes) affording polyfunctional triazenes.
Abstract: The reaction of iodo- or bromo-substituted aryltriazenes with i-PrMgCl·LiCl generates the corresponding magnesiated derivatives which react with various electrophiles (acid chlorides, 3-iodoenones, allylic halides, aldehydes) affording polyfunctional triazenes. They can be readily converted to the corresponding polyfunctional aryl iodides. This new synthetic strategy was applied to prepare functionalized carbazoles.

6 citations

Journal ArticleDOI
TL;DR: In this article, an attractive way to in situ create noble metal nanoparticles in block copolymer matrixes through the UV-triggered photodecomposition of the photolabile triazene units without the use of any conventional reducing agent was described.
Abstract: This article describes an attractive way to in situ create noble metal nanoparticles in block copolymer matrixes through the UV-triggered photodecomposition of the photolabile triazene units without the use of any conventional reducing agent. The poly(isodecyl methacrylate-co-triazene urethane methacrylate) random copolymer containing pendent photocleavable triazene junctions (COP-1) was synthesized under RAFT conditions and subsequently employed as macroinitiator to obtain a block copolymer, namely poly(isodecyl methacrylate-co-triazene urethane methacrylate)-block-poly(acrylic acid) (COP-2). The photogeneration of silver/gold metal nanoparticles (NPs) from noble metal precursors (1 wt% AgNO3 or AuBr3 metal salts) induced through the UV decomposition of triazene units with the formation of some radical active species was monitored in solution and thin films. The in situ growth of Ag/Au nanostructures into polymer matrixes for which the light is a key element has been confirmed by UV spectroscopy and TEM analysis. The TEM images allowed the visualization of the silver NPs (sizes of 4–16 nm in COP-1 and of 2–6 nm in COP-2) as well as of the gold NPs (sizes between 10 and 20 nm in COP-1 and from 15 to 25 nm in COP-2), which are mainly spherical in shape, even though there is some triangular or hexagonal gold nanoparticles.

6 citations

Journal ArticleDOI
01 Oct 1992-Talanta
TL;DR: 1-(4-Nitrophenyl)-3-(2-quinolyl)triazene has been synthesized, and used as an extremely sensitive reagent for the spectrophotometric determination of mercury by the decrease in the absorbance of the reagent at 490 nm and pH 9.0-10.8 in the presence of cetylpyridinium bromide.

6 citations

Journal ArticleDOI
TL;DR: In this paper, 1-(4-chloro-3-nitrophenyl)-3-(2-methoxyphenyl) triazene, (CNPMPT) structure was synthesized in the laboratory using new experimental methods.

6 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20236
202223
202116
202015
201917
201813