Sodium polysulfide as agent to reduce

Sodium perborate, coupling of -amino-acetanilide to 4,4 -bis(acetamido)-azobenzene using, 40, 19 Sodium polysulfide as agent to reduce 1,3 dinitro-4,6-diaminobenzene to 2,4,5-triaminonitrobenzene,... 

Sodium polysulfide as agent to reduce l,3-dinitro-4,6-diaminobenzene to 2,4,S-triaminonitrobenzene, 97... 

Traditionally, these dyes are appHed from a dyebath containing sodium sulfide. However, development in dyeing techniques and manufacture has led to the use of sodium sulfhydrate, sodium polysulfide, sodium dithionite, thiourea dioxide, and glucose as reducing agents. In the reduced state, the dyes have affinity for cellulose (qv) and are subsequendy exhausted on the substrate with common salt or sodium sulfate and fixed by oxidation. 

Sulfur Elves Sulfur dyes are inexpensive complex reaction mixtures of selected aromatic compounds with sodium polysulfide. The sulfur dyes are chemically reduced in the presence of base prior to appl ication to the fiber, and are reoxidized after dyeing on the fiber by oxygen in the air or by application of a mild oxidizing agent such as hydrogen peroxide. 

Thiosulfates also are sometimes used as reducing agents. They result from the reaction of sulfur or a polysulfide with a sulfite. Sodium thiosulfate is widely available in solid form, both anhydrous and as the pentahydrate (the photographer s hypo ). The pentahydrate crystallizes from solutions with concentrations between 30% and 60% Na2S203. The compound is quite soluble in water (33.3% at 0°C from the anhydrous form), and hypo dissolves in its water of hydration at 48°C. All forms are nontoxic under normal conditions and are used as food additives. In addition, Na2S203 forms neutral solutions. While correspondingly easier to handle than NaHS03, it is normally stored in similar equipment. 

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