Catalysts bleaching

Nonmedical uses envisaged include as growth promoters, indicators for copying processes, analytical complexing agents, cyanine dyes and dye-bleaching catalysts. 

Oil-soluble dimercaptothiadiazoles have been patented as corrosion inhibitors for copper in aqueous hydraulic fluids <2002EPP1191087>. 1,2,5-Thiadiazole dioxide-derived oxaziridines (see Section 5.09.6.1) have been patented as novel bleach catalysts for fabric detergents <1998IJSP5753599, 1998IJSP5760222>. 

Lever Bros.) enzymes, or of bleach catalysts of incompatible materials in liquid products... 

Neutral amine ligands are often applied with transition metals in higher oxidation states in polar solvents. This concept combined with the resistance of amines against oxidative conditions led to the development of novel bleaching catalysts (Structures 1-3) for washing powders by Unilever [1],... 

Pulp and paper Xylanases Used as a bleaching catalyst during pre-treatment for the manufacture of bleached pulp for paper... 

As a bleach catalyst for detergent in clearing of fabric (soiled, for example, with tea stains) or hard surfaces. 

Chlorosulfonyl isocyanate, CSI, was discovered by Graf in 1952. Since that time it has become a subject of increasing interest and importance. It has served as a precursor for the synthesis of a variety of useful products such as pharmaceutical compounds, herbicides, pesticides, liquid crystals, sweetener intermediates, and bleaching catalysts for detergents. 

Coimnon bleach activators are not very weight- and volume-effective, as they work stoichiometri-cally with peroxide. This drawback is overcome by using bleach catalysts, normally transition metal complexes with nitrogen- or oxygen-containing ligands. 

Several interesting bleach catalysts are described in recent patent literature and are currently under evaluation. Fe-TAML (tetraamido macrocyclic ligand), for example, was selected from a large number of similar tetraamido complexes, and has excellent dye transfer inhibition properties, as it selectively destroys many dyes dissolved in the wash liquor [37]. The catalyst is being tested in several applications, such as effluent bleaching, the pulp and paper industry, desulfurization of diesel, and decontamination [38]. 

A new class of bleach catalysts is based on the 2, 2 6, 2" terpyridine (terpy) ligands [43]. Whereas nonsubstituted Mn(II)-terpy complexes show only poor activity, the incorporation of electron-donating substituents in the 4-position significantly improves performance in solution and surface bleaching [44]. 

A further group of bleach catalysts is based on medium-sized azacyclic ligands, especially on cyclen or cyclam derivatives. Alkyl groups on the nitrogen atoms often have a positive impact on performance. The catalysts are relatively stable under alkaline conditions, and reach a performance optimum at 25-40°C and pH 10. Especially preferred componnds are the cyclam derivatives Mn-DEC (diethyl-cyclam) [46] and Mn-HMC (hexamethyl-cyclam) [47]. 

The bleach performance profile of aerial bleach catalysts is qnite different from that of peroxide bleaching. Whereas a wide range of oxidizable stains is attacked by the activated catalyst in the presence of perhydroxyl ions, in combination with atmospheric oxygen, only oily food stains, such as tomato oil, mango or annatto-derived stains [53], are targeted. It is assumed that under aerial bleach conditions the catalyst indnces the formation of hydroperoxides in the food stain. In a second... 

Typically, these additives are used as binders, coating agents, or carrier materials for liquids. But they might also be necessary to achieve sufficient chemical stability (see example for aerial bleach catalyst in Ref. 92), improve the dissolution profile, or simply for esthetic reasons (see example for PAP in Ref. 93). 

To achieve full bleach performance, nonactivated formulations often contain sodium carbonate or layered silicates to increase the application pH, as the perhydroxyl anion is the bleach active species. Eormulations containing bleach catalysts also work best at high pH. In contrast, TAED-based products often contain a certain amount of acidification agent, such as citric acid or sodium bicarbonate for optimum performance of peroxyacetic acid. 

Aerial bleach catalyst, terpene perfume, antioxidants... 

Amal bleach catalyst, pH <7, nonionic surfactant, fatty acid... 

Wieprecht, T., Heinz, U., Xia, J. et al., Terpyridine-Manganese Complexes A new class of bleach catalysts for detergent applications, J. Surfactant Detergents, 7 59-66, 2004. 

Jonas, E. and Reinhardt, G., Polyoxometalates—New inorganic bleach catalysts for detergent applications, J. Com. Esp. Detergents, 32 119-130 2002. 

Reinhardt, G. et al., inventor, U.S. 7205267 Use of transition metal complexes as bleach catalysts in laundry and cleaning applications, Clariant, 2007. 

Park, H. W., Lee, S. Y., Ahn., J. B. et al., Synthesis of novel bleaching catalyst containing macrocy-clic manganese complexes and potential applications in laundry detergents, J. Surfactant Detergents, 9 385-389, 2006. 

Hazenkamp, M. et al., inventor, WO 2004104155 Stable particulate composition comprising bleach catalysts, Ciba Speciality Chemicals, 2004. 

---