Side reactions from the reduction of azo dyes with dithionite / Alois Püntener in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 80, N° 1 (01-02/1996)  

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 80, N° 1 (01-02/1996) . - p. 1-5 Titre : Side reactions from the reduction of azo dyes with dithionite Type de document : texte imprimé Auteurs : Alois Püntener, Auteur ; Jens Fennen, Auteur ; C. T. Page, Auteur Année de publication : 1996 Article en page(s) : p. 1-5 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The recently introduced amendment to the Consumer Goods Act in Germany concerns itself with the prohibition of the manufacture, marketing and import of consumer goods dyed with those azo dyes, which by cleavage of the azo bond(s) can liberate certain toxic listed aromatic amines. Inmany laboratory analytical methods the reduction of the azo bond is accomplished by treatment with sodium dithionite. However, using this strong reducing agent more than just the azo groups can be cleaved as specified in ther German Act. In some cases even new amines can be generated which are neither part of the dye structure nor involved in the synthesis of the dye. These additional amines are formed by a side reaction due to the analytical procedure used and can thus lead to incorrect analytical results. The example reported here relates to the formation of 4-aminodiphenyl, when the diazo component is aniline. En ligne : https://drive.google.com/file/d/17QGfHnQspIRDUwVKSRFj5CYbROGA4O0T/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8192 [article]

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Technical considerations in black dye selection - Technical note / Alois Püntener in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXIX, N° 3 (03/1994)  

[article]  inJOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA) > Vol. LXXXIX, N° 3 (03/1994) . - p. 55-59 Titre : Technical considerations in black dye selection - Technical note Type de document : texte imprimé Auteurs : Alois Püntener, Auteur ; Z. Markovich, Auteur ; C. T. Page, Auteur Année de publication : 1994 Article en page(s) : p. 55-59 Langues : Américain (ame) Index. décimale : 675.2 Préparation du cuir naturel. Tannage Résumé : Deep black is still a fashion color in leather, and black dyes occupy an important position in the tannery dye range. Achieving deep blacks is problematical, because the tanner has to balance a number of considerations including shade, strenght, penetration, fastness properties, application method, solubility, toxicological properties, and cost. This paper provides helpful information on how to select black dyes best suited to meet current tannery requirements. It shows a method for assessing color strength, covers the influence of diluents on properties, reviews toxicological aspects, and provides application hints and fastness property information. En ligne : https://drive.google.com/file/d/1VpEEqvCeeeL4xPjbAZmutC3H-Ww95WJx/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=8087 [article]

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The challenge of manufacturing leather dyes today / C. T. Page in JOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC), Vol. 82, N° 2 (03-04/1998)

[article]  inJOURNAL OF THE SOCIETY OF LEATHER TECHNOLOGISTS & CHEMISTS (JSLTC) > Vol. 82, N° 2 (03-04/1998) . - p. 75-77 Titre : The challenge of manufacturing leather dyes today Type de document : texte imprimé Auteurs : C. T. Page, Auteur ; Jens Fennen, Auteur Année de publication : 1998 Article en page(s) : p. 75-77 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 675 Technologie du cuir et de la fourrure Résumé : The introduction in July 1994 bye the German parliament of an amendment to their Consumer Goods Act, which prohibited certain azo dyes, has had consequences world-wide at all levels of the leather industry. The general thrust behind the law has strong support at all levels in the industry but the fine details have caught many unaware of their practical implications. Ther German law makers have found they needed several further amendments to bring even some degree of workability to the legislation. The test institutes world-wide have discoveres an exceedingly lucrative new business niche in chemical analysies. Those in the leather manufacturing chain, from tanners all over the world through to the German retail shops, have had to subject their products to analytical scrutiny at the parts per million level have discovered the limits of analytical methods. The German Act probihits the use of certain azo dyes in defined consumer goods that come into repeated contact with the skin. The azo dyes affected by this legislation are those that after splitting up of the dye molecule at eht azo groups release any of the 20 amines listed in the Act. Those involved in developing the analytical method quickly discovered it is easy to legally define this splitting up of dye molecules, but in practice much more difficult to implement so that only amines from the splitting of the azo group were detected. Dye molecules are happy to split in other ways if the reaction conditions are sufficient. Any type of correlation with the real life in vivo reduction reactions was never considered as the analysts struggled within strict time constraints to produce a German standard test method. The manufacture of a dye today, taking into account all the constraints of the above legislation, can lead to "clean" dyes being labelled as doubtful. The manufacturing process of a dye will be followed to show how such a situation could arise. It is clear that there are still areas of greynes in the Act as it stands, but the rapid expansion of this type of legislation within Europe means that all in the leather industry will have to work with the current political, commercial and analytical compromise situation. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7869 [article]

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