A disadvantage of these compounds compared to the standard compound TAED is their usually poorer economic and ecological performance. The literature describes a variety of active N-acyl compounds, such as tetraacetyl glycoluril and other acylated saturated nitrogen-containing heterocycles, such as hydantoins, hydrotriazines, diketopiperazines, etc., as well as acylated imides and lactams.
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In all cases, the activator is chemically reacted according to the degree of contamination in the laundry and thus "consumed". For example, TAED produces in the wash liquor bleach-active peroxyacetic acid or from DOBA peroxydodecanoic acid. Typical bleach activators are essentially N- and O-acyl compounds that form peroxyacids upon perhydrolysis (meaning hydrolysis by hydrogen peroxide from the bleach, persalts). Therefore, they are also used in dishwashing detergents and denture cleaners. In addition to stain bleaching in laundry, the disinfecting and deodorizing effects of bleach/activator combinations also play an important role. There remains considerable potential in Europe for more active bleach activators due to the significant potential energy savings achievable by washing at lower temperatures, but their higher activity must not be accompanied by greater damage to textile dyes and fibers. The relatively high cost of conventional bleaching systems restrict their spread in emerging markets, where cold water is used for washing and photobleaching by sunlight is widespread, or the use of sodium hypochlorite solution is common (as in the US). Consumption, however, is stagnant or declining due to cost pressures on detergents and the advance of liquid detergent formulations (which contain no bleach and bleach activators). The consumption of bleach activators in 2002 was approximately 105,000 tonnes. Once formed, the peroxy acid can act as a bleach. In aqueous solutions, the hydroxide ion is also present, but owing to the greater nucleophilicity of the perhydroxyl anion, it will react preferentially. Only the perhydroxyl anion, and not the hydrogen peroxide molecule, reacts with the bleach activator. The overall reaction of TAED ( 1) with 2 equivalents of hydrogen peroxide gives diacetylethylenediamine ( 2) and 2 equivalents of peracetic acid ( 3): The perhydroxyl anion then attacks the activator, forming a peroxy acid: In a basic wash solution, hydrogen peroxide loses a proton and is converted to the perhydroxyl anion: When dissolved in water, the persalt releases hydrogen peroxide ( e.g. In the wash, both compounds dissolve in the water. Persalts and bleach activators are included together in powder laundry detergents that contain bleach. Persalts are inorganic salts that are used as hydrogen peroxide carriers (examples include sodium percarbonate and sodium perborate). Mechanism of activation īleach activation is also known as perhydrolysis. The leaving group influences the solubility, perhydrolysis rate and storage stability of the activator. The peroxy acid precursor affects the bleaching properties of the peroxy acid: determining the activity, selectivity, hydrophobic/hydrophilic balance and oxidation potential. Structure and properties īleach activators are typically made up of two parts: the peroxy acid precursor and the leaving group and are modified by altering these parts. and Japan, TAED is the main activator used in Europe. NOBS is the main activator used in the U.S.A. The most common bleach activators used commercially are tetraacetylethylenediamine (TAED) and sodium nonanoyloxybenzenesulfonate (NOBS). Peroxy acids are more active bleaches than hydrogen peroxide at lower temperatures (<60 ☌), but are too unstable to be stored in their active form, and hence must be generated in situ. Bleach activators react with hydrogen peroxide in aqueous solution to form peroxy acids. They are not included in any liquid laundry detergents. Tide), some laundry additive powders, and a few laundry additive pods.
Bleach activators are included in some laundry detergent powders (e.g. With bleach activators, this activity can be achieved at lower temperatures. Bleaching agents, usually peroxides, are usually sufficiently active only at 60 ☌ and up.
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Sodium nonanoyloxybenzenesulfonate (NOBS)īleach activators are compounds that allow a lower washing temperature than would be required otherwise to achieve the full activity of bleaching agents in the wash liquor.
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