GB636399A - Manufacture of reducing agents derived from alkali sulphides and dyestuffs preparations containing them - Google Patents

Abstract

Reducing agents are made by reacting a degradation product of a high molecular weight natural carbohydrate or a low molecular weight carbohydrate with an alkali sulphide in concentrated aqueous solution at a raised temperature not substantially above 108 DEG C., and drying at a temperature not substantially above 108 DEG C. A sulphur dye or its leuco-body may be incorporated dry in the dry product, or the leuco-body may be incorporated wet or dry, before or after drying of the reducing agent itself, followed by drying. The dye may be vatted with excess alkali sulphide and the carbohydrate product added, followed by drying. Carbohydrate products specified are dextrin, British gum, cane sugar, glucose, l vulose. The sulphide may be sodium sulphide or hydrosulphide. In examples: (1) dextrin, cane sugar, glucose, or l vulose is mixed with sodium sulphide fused in its own water of crystallization, followed by drying; (2) the dye obtained by sulphurizing N-p-hydroxyphenyl - N1 - o - carboxyphenyl - p - phenylene diamine is mixed dry with the product of (1), or converted to its leuco-body with sodium sulphide and the dry leuco-body mixed with the product of (1), or vatted with sodium sulphide in presence of dextrin, followed by drying only, and by drying and mixing with the product of (1). Also in examples: (3) Pyrogene Deep Black P is vatted with excess sodium sulphide and dextrin; followed by drying; (4) Pyrogene Yellow O is mixed dry with the product of (1) or vatted with sodium sulphide and dextrin. Specification 418,746 is referred to.ALSO:Reducing agents are made by reacting a degradation product of a high molecular weight natural carbohydrate or a low molecular weight carbohydrate with an alkali sulphide in concentrated aqueous solution at a raised temperature not substantially above 108 DEG C., and drying at a temperature not substantially above 108 DEG C. A sulphur dye or its leuco-body may be incorporated dry in the dry product, or the leuco-body may be incorporated wet or dry before or after drying of the reducing agent itself, followed by drying. The dye may be vatted with excess alkali sulphide and the carbohydrate product added, followed by drying. Carbohydrate products specified are dextrin, British gum, cane sugar, glucose, lacvulose. The sulphide may be sodium sulphide or hydrosulphide. In examples: (1) dextrin, cane sugar, glucose, or lacvulose is mixed with sodium sulphide fused in its own water of crystallization, followed by drying; (2) the dye obtained by sulphurizing N - p - hydroxyphenyl - N1 - o - carboxyphenyl-p-phenylene diamine is mixed dry with the product of (1), or converted to its leuco-body with sodium sulphide and the dry leuco-body mixed with the product of (1), or vatted with sodium sulphide in presence of dextrin, followed by drying only, and by drying and mixing with the product of (1). Also in examples: (3) Pyrogene Deep Black D is vatted with excess sodium sulphide and dextrin, followed by drying; (4) Pyrogene Yellow O is mixed dry with the product of (1) or vatted with sodium sulphide and dextrin. A dyeing example is also given. Specification 418,746 is referred to.