Metal Complexes for Cotton see also Section

As opposed to copper complex dyes, 1 2 chromium and cobalt complexes can only be bound to cotton if a fiber-reactive group is incorporated in the dye backbone [32], For example, the reactive 1 2 chromium-cobalt complex 20 C.I. Reactive Black 8, 18207 M = Cr/Co = ca. 3 1 M = Cr [ 79828-44-7] M = Co [79817-89-3] provides black prints on cotton, whereby the corresonding pure 1 2 chromium 

Copper-containing substantive dyes such as 21 C.I. Direct Blue 93, 22810 [13217-74-8] have long been used for coloring cotton [34], 

The Benzo Fast Copper (I.G. Farbenindustrie) and the Cuprophenyl (Geigy) dyes are converted to insoluble copper complexes on the fiber by treating the dyeings with a copper salt. Copper complex formation on the fiber has strongly lost technical significance due to the copper content in dyehouse effluents. The mostly copper-containing Indosol direct dyes recently launched by Sandoz are cross-linked on and with the fiber by aftertreatment with a special reactive agent [35], 

In demethylative coppering to give the bis-copper complex 22 [74592-99-7] (3 Na, Li salt) [36], the sodium salt of the disazo compound made by coupling of bis-diazotized 3,3 -dimethoxy-4,4 -diaminodiphenyl with two equivalents of 8-amino-l-hydroxynaphthalene-3,6-disulfonic acid in alkaline medium is dissolved in water by adding diethanolamine. An ammonia alkaline copper(n) sulfate solution made from CuS04-5 H20 and of ammonia are added. The mixture is heated at 80-90 °C for 14 h. The solution is then cooled to 40 °C and the bis-coppered dye 22 salted out with sodium chloride. It dyes cotton in lightfast blue shades. 

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