Kinetische Wasserstoffisotopeneffekte und allgemeine Basenkatalyse der Azokupplung. Zur Kenntnis der Kupplungsreaktion, 9. Mitteilung

Abstract

Volumen XXXVIII, Fasciculus VI (1955) -No. 192-193. 1597 9,l g, 37,4% de &tones. 8,6 g sont traites avec 14 g de borate d'ethyle comme indique plus haut. Les 5,5 g d'ester borique sont saponifies avec 15 ml de KOH alcoolique 10% pendant 2 h. On obtient 5,2 g dc produit dont 4,9 g distillant sous 0,12 torr entre 72 et 73O; d:2,5 = 0,9620, n$ = 1,4980. Rendement calcule sup la dih-y presente dans le produit de depart 86%. DCtermination de la vitesse d'isomCrisation par l'acide sulfurique CE ZOyo. On prepare 46chantiIlons contenant 5g du m6me melange (dihydro-ionones c t e t y, 94,876 de cetones) et 50 ml d'acide sulfurique a 20%. On les agite L temperature ambiante, le premier 5 h, le second 10 11, lo troisittme 24 h et le quatrikme 48 h. Dans les produits de reaction extraits A Yether, on determine ensuite la teneur en cirtones par oximation. lo 55,2y0 ; 2 O 47,0% ; 3 O 37,8%; 4O 37,6%. A p r h 24 h, l'isomerisation est donc pratiquement complkte.SUMMARY.

Micellar Effects on Dediazoniation and on Azo Coupling Reactions

“…Coupling rates change dramatically with pH because free amines and phenoxide or naphthoxide ions are much more reactive than their protonated forms (9)(10)(11)(12)(13). Therefore, the control of pH in azo-coupling reactions is of primary importance, particularly since the concentration of the active arenediazonium ion decreases rapidly in alkaline solution due to the competing reaction of arenediazonium ions with OH − to form diazotates becomes significant, which makes it so that the coupling reaction under strongly alkaline conditions is not usually possible (3,(13)(14)(15).…”

Dediazoniations of Arene Diazonium Ions in Homogenous Solution. Part IV: Change‐over from a heterolytic to a homolytic mechanism in 2,2,2‐trifluoroethanol pyridine mixtures

“…In other related systems, e.g. in water [13] and in pyridine [8] (141, diazopyridinium ions have been detected by various methods. We have begun a detailed study of these equilibria in TFE/pyridine systems.…”

Azo Dyes

“…In the manufacture of trisazo dyes, good yield and purity during final coupling are often obtained only in the presence of pyridine or other bases as coupling accelerators [35]. Intermediate isolation and separation of impurities prior to continuation of coupling are also frequently necessary.…”