Azo Coupling Reaction of Heterocyclic Diazo Compounds

Sawaguchi, H.; Hashida, Yoji; Matsui, Kohji

doi:10.1246/nikkashi1898.74.9_1859

Cited by 8 publications

(4 citation statements)

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“…Sawaguchi et al [9] have measured the rate of azo coupling of various heteroaromatic diazonium ions with 2-naphthol-3,6-disulfonic acid. There exist an extensive patent literature on azo dyes synthesized with heteroaromatic diazonium ions since Dickey and Towne realized in the early 1950s, that industrially interesting disperse dyes can be obtained on this basis.…”

Section: Introductionmentioning

confidence: 99%

Azocalixarenes. 3

et al. 2004

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Section: Introductionmentioning

confidence: 99%

Azocalixarenes. 3

et al. 2004

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“…For X-azo-2-naphthol-3,6-disulfonic acid derivatives (Chart S3), the deprotonation of the hydroxyl group whose hydrogen atom forms a hydrogen bond with the β-N atom was reported to depend on the basicity of the β-N atom: (1) when X is a substituted benzene ring, the substituent had little effect on the p K a (p K a = 11.03 for X = p -CH 3 C 6 H 4 and 10.22 for X = p -NO 2 C 6 H 4 ), and (2) when X was a thiazole ring rather than a benzene ring, the p K a decreased by 3 orders of magnitude (p K a = 8.07 for X = thiazol-2-yl and 7.87 for X = benzothiazol-2-yl) due to the highly electron-withdrawing properties of the thiazole structure . A similar trend in the p K a values was observed for the azoB s (Table ), perhaps because the basicity of the β-N atom also plays a role in determining their p K a B .…”

Section: Resultsmentioning

confidence: 99%

o-Azophenylboronic Acid-Based Colorimetric Sensors for d-Fructose: o-Azophenylboronic Acids with Inserted Protic Solvent Are the Key Species for a Large Color Change

et al. 2020

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Many boronic acid-based chemosensors for saccharides have been developed; however, their detection mechanisms have seldom been studied. In this study, we synthesized 10 o-azophenylboronic acid derivatives (azoBs) and conducted a fundamental study on the reactivity and the sensing mechanism of azoBs, which undergoes a large color change, e.g., from red to yellow, upon a reaction with saccharides. Their pH-independent formation constants were determined by spectrophotometric titration and then converted to the conditional formation constant K′ at pH 7.4. A linear free energy relationship was established between log K′ and the pK a of azoB. 11B NMR measurements indicate that in aprotic solvents, azoB forms a trigonal planar structure, while in protic solvents, it forms a quasi-tetrahedral structure (azoB-ROH) with a protic solvent molecule (ROH) inserted between the boronic acid moiety and the azo group. In addition, UV–vis spectroscopic studies showed that the color change during the reaction between azoB and d-fructose in ROH was caused by the release of the ROH from azoB-ROH by d-fructose. Based on the findings in this study, we proposed a guideline for designing an azoB-based chemosensor that exhibits high reactivity toward saccharides and a sufficient color change to allow for the visual detection of saccharides.

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“…Under our azo coupling conditions (pH 4.01 -5.97) the equilibrium is almost completely on the side of the zwitterion 7 in eq. [3]. The mesomeric structure 7b demonstrates (7) in Fig.…”

Section: Discussionmentioning

confidence: 94%

“…Goerdeler and Haubrich (2) have made a semiquantitative comparison of the reactivity of 3-phenyl-1,2,4-thiadiazole-5-diazonium ion with 2-naphthol and the respective reaction with 2,4-dinitrobenzenediazonium ion. Sawaguchi et al (3) have measu~ed the rate of azo coupling of various heteroaromatic diazonium ions with 2-naphthol-3,6-disulfonic acid. There exists an extensive patent literature on azo dyes synthesized with heteroaromatic diazonium ions since Dickey and Towne realized in the early 1950s that industrially interesting disperse dyes can be obtained on this basis.…”

Section: Introductionmentioning

confidence: 99%

Mechanism of azo coupling reactions. Part 34. Reactivity of five-membered ring heteroaromatic diazonium ions

Diener¹,

Zollinger²

1986

Can. J. Chem.

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. Can. J. Chem. 64, 1102Chem. 64, (1986. The azo coupling reactions of six five-membered ring heteroaromatic diazonium ions with 2-naphthol-3,6-disulfonic acid are investigated kinetically at various pH values. The dependence of the measured rate constants on the acidity of the aqueous reaction system is evaluated. It can be shown that the 2-naphtholate-3,6-disulfonate trianion reacts4 x 10' -8 x 10' times faster than the 2-naphthol-3,6-disulfonate dianion. The rate constants of the six diazonium ions vary by more than four orders of magnitude. The logarithms of the rate constants of all comparable diazonium ions correlate linearly with 'H nmr chemical shifts of the respective unsubstituted heteroaromatic parent compounds. An analogous correlation was found for azo couplings with substituted benzenediazonium ions. Diazotization of heteroaromatic amines does not go to completion, rather to an equilibrium. It is shown therefore that in acidic coupling systems the azo compound is only the kinetically controlled product. The thermodynamic products are l-nitroso-2-naphthol-3,6-disulfonic acid and the heteroaromatic amine.HEINZ DIENER et HEINRICH ZOLLINGER. Can. J. Chem. 64, 1102 (1986). Operant i divers pH, on a ttudit la cinttique de rtactions de couplage azo entre six ions diazonium d'htttrocycles aromatiques i cinq chainons et l'acide naphtol-2 disulfonique-3,6. On a tvalut la dtpendance des constantes de vitesses mesurtes sur I'aciditt du systkme aqueux de lartaction. On peut dtmontrer que le trianionnaphtolate-2 disulfonate-3,6 rtagit de 4 x 108i 8 X 10' plus rapidement que le dianion naphtol-2 disulfonate-3,6. Les constantes de vitesse pour les six ions diazonium varient par plus de quake ordres de grandeurs. I1 existe une corrtlation linkaire entre les constantes de vitesse de tous les ions diazonium comparables et les dtplacements chimiques en rmn du 'H des composts htttroaromatiques debase qui ne sont pas substitues. On a pu ttablir une corrtlation analogue pour les couplages azo avec des ions benzknediazonium substituts. La rtaction de diazotation des amines htttroaromatiques n'est pas complkte; il s'agit plutBt d'un tquilibre. On dtmontre alors que, dans les systkmes de couplages acides, les composts azo ne sont que les produits de contrBle cinttique. Les produits de contrtile thermodynamique sont l'acide nitroso-1 naphtol-2 disulfonique-3,6 et I'amine htttroaromatique.[Traduit par la revue]

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Azo Coupling Reaction of Heterocyclic Diazo Compounds

Cited by 8 publications

References 0 publications

Azocalixarenes. 3

Azocalixarenes. 3

o-Azophenylboronic Acid-Based Colorimetric Sensors for d-Fructose: o-Azophenylboronic Acids with Inserted Protic Solvent Are the Key Species for a Large Color Change

Mechanism of azo coupling reactions. Part 34. Reactivity of five-membered ring heteroaromatic diazonium ions

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