Manganese bleaching

At present, chlorine dioxide is primarily used as a bleaching chemical in the pulp and paper industry. It is also used in large amounts by the textile industry, as well as for the aching of flour, fats, oils, and waxes. In treating drinking water, chlorine dioxide is used in this country for taste and odor control, decolorization, disinfection, provision of residual disinfectant in water distribution systems, and oxidation of iron, manganese, and organics. The principal use of chlorine dioxide in the United States is for the removal of taste and odor caused by phenolic compounds in raw water supplies. 

Ordinary alkenes (without an allylic OH group) have been enantioselectively epoxidized with sodium hypochlorite (commercial bleach) and an optically active manganese-complex catalyst. Variations of this oxidation use a manganese-salen complex with various oxidizing agents, in what is called the Jacobsen-Katsuki... 

Fueled by the success of the Mn (salen) catalysts, new forays have been launched into the realm of hybrid catalyst systems. For example, the Mn-picolinamide-salicylidene complexes (i.e., 13) represent novel oxidation-resistant catalysts which exhibit higher turnover rates than the corresponding Jacobsen-type catalysts. These hybrids are particularly well-suited to the low-cost-but relatively aggressive-oxidant systems, such as bleach. In fact, the epoxidation of trans-P-methylstyrene (14) in the presence of 5 mol% of catalyst 13 and an excess of sodium hypochlorite proceeds with an ee of 53%. Understanding of the mechanistic aspects of these catalysts is complicated by their lack of C2 symmetry. For example, it is not yet clear whether the 5-membered or 6-membered metallocycle plays the decisive role in enantioselectivity however, in any event, the active form is believed to be a manganese 0x0 complex <96TL2725>. 

Martens, R. J. Swarthoff, T. (Unilever). Detergent Compositions Containing Dinuclear Manganese Complex as Bleach. Canadian Patent 2,083,661, 27 May, 1993. 

Epoxidation using manganese salen complexes is very easy to carry out it occurs under aqueous conditions and commercial house bleach can be used as the oxidant. The results are similar to those reported in the literature Table 6.1 gives other examples of alkenes which can be epoxidized using the same procedure. This method gives good results, especially for disubstituted Z-alkenes but trisubstituted alkenes can be epoxidized as well. 

Michel, F.C.J. Dass, S.B. Grulke, E.A. Reddy, C.A. Role of manganese peroxidases (MNP) and lignin peroxidases (LiP) of Phanerochaete chrysosporium in the decolorization of Kraft bleach plant effluent. Appl. Environ. Microbiol. 1991, 57, 2368-2375. 

Jaspers, C.J. Jiminez, G. Penninck, M.J. Evidence for a role of manganese peroxidase in the decolorization of Kraft pulp bleach plant effluent Phanerochaete chrysosporium effects of initial culture conditions on enzyme production. J. Biotechnol. 1994, 37, 229-234. 

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