Bleaches peracid precursors

Peracid Precursor Systems. Compounds that can form peracids by perhydrolysis are almost exclusively amide, imides, esters, or anhydrides (85). Two compounds were commercially used for laundry bleaching as of 1990. Tetraacetylethylenediarnine (TAED) [10543-57-4] is utilized in over 50% of Western European detergents (5). The perhydrolysis reaction of this compound is shown in equation 19. T A ED generates two moles of peracid and one mole of diacetylethylenediamine per mole of imide (93). 

The NOBS system undergoes an additional reaction that forms a diacyl peroxide as a result of the nucleophilic attack of the peracid anion on the NOBS precursor as shown in equation 21. This undesirable side reaction can be minimized by the use of an excess molar quantity of hydrogen peroxide (91,96) or by the use of shorter dialkyl chain acid derivatives. However, the use of these acid derivatives also appears to result in less efficient bleaching. The dependence of the acid group on the side product formation is apparentiy the result of the proximity of the newly formed peracid to unreacted NOBS in the micellar environment (91). A variety of other peracid precursor stmctures can be found (97—118). 

In contrast to sensitive preformed peracids, bleach activators are safe to handle and, in granulated form, reasonably storage-stable in alkaline detergent powders or tablets. Bleach activators are organic compounds having at least one reactive acyl group R-CO (peracid precursor group), which... 

Providiug delayed release of ingredients which degrade enzymes in the wash water. This approach has been used for peroxygen bleaches [70], accomplished by coating the peracid precursor with polyethylene glycol (MW 4000) and citric acid and the percarbonate with silicate. 

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