Water-soluble fiber-reactive colorants, method for the production thereof, and use their use

#The invention relates to the field of fiber-reactive azo dyes.

#DE-A-3516667 describes green to olive metal complex dyes for use as reactive dyes for cotton, wool or nylon. However, they have certain application defects, for example an excessive dependence of the color yield on varying parameters in the dyeing process, or an inadequate or unlevel build-up on cotton, good build-up resulting from the ability of a dye to provide a stronger dyeing when used in a higher dye concentration in the dyebath. Moreover, these dyes exhibit unsatisfactory fixation yields, i.e., the portion of dye permanently fixed on the material to be dyed is too low, especially at low temperatures, and also unsatisfactory washfastnesses.

#However, it is important, for ecological and economic reasons, to provide dyes having particularly high fixation yields in order that the portion of unfixed dye in the dyehouse effluent may be minimized. Moreover, dyes should always provide uniformly strong dyeings, ideally regardless of changing dyeing parameters, for example the dyeing temperature in the dyeing process. Furthermore, washfastness requirements are more stringent these days.

#The examples hereinbelow serve to illustrate the invention. Parts and percentages are by weight, unless otherwise stated. The compounds described in the examples in terms of a formula are partly indicated in the form of free acids; in general these compounds are prepared and isolated in the form of their salts, preferably sodium or potassium salts, and used for dyeing in the form of their salts. The starting compounds mentioned in the following examples, especially table examples, can similarly be used in the synthesis in the form of the free acid or in the form of their salts, preferably alkali metal salts, such as sodium or potassium salts.

#a) 20.3 parts of 3-amino-4-methoxybenzenesulfonic acid are dissolved in 100 parts of water under neutral conditions and admixed with 30 parts of concentrated hydrochloric acid and 30 parts of ice. 6.9 parts of sodium nitrite in 100 parts of water are added with stirring and subsequently stirred in for 60 minutes. Excess nitrite is destroyed with amidosulfonic acid. 15.3 parts of 3,4-dimethoxyaniline are added and the pH is adjusted to 4.0 with 10% sodium carbonate solution for 2 hours. The precipitated dye is filtered off with suction.

#b) The dye prepared under a) is dissolved under neutral ocnditions, admixed with 6.9 parts of sodium nitrite and added dropwise with thorough stirring to a mixture of 30 parts of ice and 50 parts of concentrated hydrochloric acid. This is followed by 15 minutes of stirring when excess nitrite is destroyed with amidosulfonic acid. 31 parts of 5-hydroxy-1,7-disulfo-2-naphthylamine are added and the batch is slowly adjusted to pH 5 with 10% sodium carbonate solution.