Photo-reductive fading of disperse azo dyes on nylon substrate: thermochemical analyses of reactions of photo-induced radicals using the semiempirical molecular orbital method / Yasuyo Okada in COLORATION TECHNOLOGY, Vol. 125, N° 6 (2009)  

[article]  inCOLORATION TECHNOLOGY > Vol. 125, N° 6 (2009) . - p. 305-321 Titre : Photo-reductive fading of disperse azo dyes on nylon substrate: thermochemical analyses of reactions of photo-induced radicals using the semiempirical molecular orbital method Type de document : texte imprimé Auteurs : Yasuyo Okada, Auteur ; Toshio Hihara, Auteur ; Zenzo Morita, Auteur Année de publication : 2010 Article en page(s) : p. 305-321 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 667.3 Teinture et impression des tissus Résumé : When the excited triplet states of disperse azo dyes with nitro groups abstract hydrogen to generate hydrazinyl (from azo groups) and nitrosyl hydroxide radicals (from nitro groups), both the radicals as H-acceptors carry out azo scission, conversion to nitrogen dioxide via disproportionation reactions and self-decomposition via rearrangement. A kinetic equation was formulated by the sum of these reactions, which describes the initial rates (KPA) of reductive fading. The KPA values were controlled by the rate constants of the reactions of hydrazinyl and nitrosyl hydroxide radicals as H-acceptors, which were estimated by thermochemical analyses of the reactants, intermediates and end products using the semiempirical molecular orbital PM5 method, and by the concentrations of the reactants: H-acceptors and H-donors. The KPA values observed for 12 dyes were explained semi-quantitatively by multiple routes of reactions depending upon to what extent each radical reaction was thermochemically favoured. DOI : 10.1111/j.1478-4408.2009.00212.x En ligne : http://onlinelibrary.wiley.com/doi/10.1111/j.1478-4408.2009.00212.x/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7620 [article]

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Photofading of phenylazo-aniline, -pyridone and -quinolone disperse dyes on a nylon 6 substrate / Yasuyo Okada in COLORATION TECHNOLOGY, Vol. 125, N° 2 (2009)  

[article]  inCOLORATION TECHNOLOGY > Vol. 125, N° 2 (2009) . - p. 86-98 Titre : Photofading of phenylazo-aniline, -pyridone and -quinolone disperse dyes on a nylon 6 substrate Type de document : texte imprimé Auteurs : Yasuyo Okada, Auteur ; Zenzo Morita, Auteur ; Toshio Hihara, Auteur Année de publication : 2009 Article en page(s) : p. 86-98 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 667.3 Teinture et impression des tissus Résumé : The photofading of phenylazo-aniline, -pyridone and -quinolone disperse dyes on nylon fabric was analysed using the Kubelka–Munk (K/S) spectra of fabrics exposed to a carbon arc in air. The exposure of dyed fabric through ultraviolet and coloured filters, which do not shield the main absorption band, showed a large decrease in the initial rate (KPA) of fading. Compared with the KPA values without filters, the values using filters were half as large for dyes without the nitro groups and a quarter as large for dyes with the nitro groups. The KPA values may be qualitatively explained by the sum of azo scission (decrease of K/S value at lambda max) and the conversion of nitro groups to nitroso groups. These phenomena occur, respectively, via thermal disproportionation reactions between hydrazinyl radicals (from the azo group) and the reaction between hydrazinyl and N-centred nitrosyl hydroxide radicals (from the nitro group). The azo scission is promoted by N-centred nitrosyl hydroxide radicals via the latter reactions. DOI : 10.1111/j.1478-4408.2009.00179.x En ligne : http://onlinelibrary.wiley.com/doi/10.1111/j.1478-4408.2009.00179.x/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4853 [article]

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Radical mechanism of azo cleavage for monoazo reactive dyes, a QSPR study : the similarity between photoreduction on polyamide substrates and thermal reduction in aqueous dithionite solutions / Yasuyo Okada in COLORATION TECHNOLOGY, Vol. 132, N° 4 (08/2016)  

[article]  inCOLORATION TECHNOLOGY > Vol. 132, N° 4 (08/2016) . - p. 327-343 Titre : Radical mechanism of azo cleavage for monoazo reactive dyes, a QSPR study : the similarity between photoreduction on polyamide substrates and thermal reduction in aqueous dithionite solutions Type de document : texte imprimé Auteurs : Yasuyo Okada, Auteur ; Toshio Hihara, Auteur ; Zenzo Morita, Auteur Année de publication : 2016 Article en page(s) : p. 327-343 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Colorants azoïques Colorants réactifs Dithionite de sodium Polyamide 6 Réduction (chimie) Solutions aqueuses (chimie) Thermochimie Index. décimale : 667.3 Teinture et impression des tissus Résumé : The same radical mechanism occurs in reductive azo cleavage via monohydrogenated radicals generated as the starting reactants in photo- and thermal (by dithionite) reduction on a nylon 6 substrate and in aqueous and alcoholic solutions. The rates of photo- and thermal azo cleavage in the solid and liquid phases have been thermochemically analysed by calculating the heats of formation of the reactants, intermediates, and products for (1) intramolecular hydrogen transfer (self-decomposition via rearrangement) in the photo- and radically induced hydrazinyl radicals as well as for (2) the disproportionation (redox reaction) between the radicals via a molecular orbital method. The rates of reductive fading (or azo cleavage) are controlled by the heats of reaction via reaction pathways (1) and (2) as well as by rearrangement, depending on the reaction system. Photoreduction of these dyes on polyamide generated the same end products – diazo components and iminooxoquinones from the coupling component – as the products of thermal reduction in aqueous sodium dithionite and of photoreduction in the liquid phase. Photofading on polyamide substrates owing to continuous irradiation is controlled by three factors: the quantum yield of photoinduced hydrazinyl radicals, its rearrangement processes, and the heats of reaction for the thermal azo cleavage reactions via the two pathways. These factors may become molecular descriptors that correlate the rates of fading with molecular structures. The present study may become an introductory trial to construct quantitative structure–property relationship modelling for reduction-fast azo dyes. Note de contenu : - EXPERIMENTAL : Dyes used - Parameters used for the analysis - Materials : dyeing and exposure - RESULTS AND DISCUSSION : Formation of the (MHN) moiety - Thermochemical analysis for the rates of thermal reduction of food azo dyes - Rates of photoreduction for model azo dyes in an alcoholic aqueous solution - Photoreduction of reactive azo dyes on PA substrates DOI : 10.1111/cote.12223 En ligne : https://onlinelibrary.wiley.com/doi/epdf/10.1111/cote.12223 Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=26735 [article]

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Relationship between photofading and chemical structure of disperse azo dyes on nylon fabric / Yasuyo Okada in COLORATION TECHNOLOGY, Vol. 126, N° 4 (2010)  

[article]  inCOLORATION TECHNOLOGY > Vol. 126, N° 4 (2010) . - p. 215-230 Titre : Relationship between photofading and chemical structure of disperse azo dyes on nylon fabric Type de document : texte imprimé Auteurs : Yasuyo Okada, Auteur ; Toshio Hihara, Auteur ; Mie Hirose, Auteur ; Zenzo Morita, Auteur Année de publication : 2010 Article en page(s) : p. 215-230 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 667.3 Teinture et impression des tissus Résumé : The initial rates of photofading for 30 disperse azo dyes on nylon fabric upon exposure to a carbon arc in air have been analysed by formulating a kinetic equation that describes azo scission via the disproportionation reactions and intramolecular H-transfer by two kinds of hydrazinyl radicals and the conversion of a nitro group to a nitroso group via the disproportionation reaction of nitrosyl hydroxide radicals. The five reaction rate constants are discussed in terms of the heats of reaction by calculating the heats of formation for the reactants, intermediates and products of each reaction using the PM5 method. Phenylazo- and thiazoleazo-N,N-substituted anilines and phenylazo-pyridones exhibited large rate constants of multiple terms, while phenylazo-phenols had the highest light fastness and very small rate constants for the disproportionation reactions of hydrazinyl radicals. Photofading on nylon fabric was primarily controlled by the thermal reactions of photo-induced monohydrogenated dye radicals, which occurred via one or two primary multiple routes. Note de contenu : EXPERIMENTAL : Dyes used - Method of dyeing, exposure and molecular orbital calculation. RESULTS AND DISCUSSION : Photofading behaviours on PA fabric - Azo scission by reaction of hydrazinyl radicals with MHN radicals - Multiple reaction routes exhibiting fading ratios and Kpa values - Thermochemical analysis of PAPs - General conclusions regarding thermochemical analysis of azo dyes - Relationship between chemical structure and reductive fading. DOI : 10.1111/j.1478-4408.2010.00250.x En ligne : http://onlinelibrary.wiley.com/doi/10.1111/j.1478-4408.2010.00250.x/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=9874 [article]

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Substituent effects on the photofading of disperse azo dyes on poly(ethylene terephthalate) substrate / Yasuyo Okada in COLORATION TECHNOLOGY, Vol. 126, N° 3 (2010)  

[article]  inCOLORATION TECHNOLOGY > Vol. 126, N° 3 (2010) . - p. 127-139 Titre : Substituent effects on the photofading of disperse azo dyes on poly(ethylene terephthalate) substrate Type de document : texte imprimé Auteurs : Yasuyo Okada, Auteur ; Toshio Hihara, Auteur ; Mie Hirose, Auteur ; Zenzo Morita, Auteur Année de publication : 2010 Article en page(s) : p. 127-139 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 667.3 Teinture et impression des tissus Résumé : The relationships between the chemical structures and oxidative fading of the disperse azo dyes, p-nitrophenylazo- and benzothiazoleazo-anilines, on poly(ethylene terephthalate) substrate are discussed in terms of the parameters k0,i (rate constants of reaction towards 1O2) and fi (photosensitivity), the molecular parameters of molecular orbital theory and substituents in the diazo and coupling components, on the assumption that the initial rates of oxidative fading are proportional to the product of k0,i and fi. 2-Methoxy-5-acetylamino-N-substituted aniline couplers exhibited large fi values. 2-Chloro and 4-nitro substituents of aniline diazo components exhibited small fi values or high quantum yields of internal conversion, while 4-nitro substituent did not. A close correlation between N-substituents and light fastness, proposed by Müller and supplemented by Dawson, demonstrates the applicability of frontier orbital theory, through the highest occupied molecular orbital (HOMO) energy of the dyes, to the analysis of oxidative fading. Dyes with N-2-cyanoethyl substituents, which gave a lower HOMO energy, also exhibited superior light fastness compared with N-2-hydroxyethyl substituents. DOI : 10.1111/j.1478-4408.2010.00237.x En ligne : http://onlinelibrary.wiley.com/doi/10.1111/j.1478-4408.2010.00237.x/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=9457 [article]

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