Tetraacetylethylenediamine

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Tetraacetylethylenediamine
Tetraacetylethylenediamine.png
Identifiers
CAS number 10543-57-4 N
PubChem 66347
ChemSpider 59725 N
Jmol-3D images Image 1
Properties
Molecular formula C10H16N2O4
Molar mass 228.25
Appearance colourless solid
Density 0.9
Melting point 149 to 154 °C (300 to 309 °F; 422 to 427 K)
Solubility in water 0.2 g/L @ 20ºC
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Tetraacetylethylenediamine, commonly abbreviated as TAED, is an organic compound with the formula (CH3C(O))2NCH2CH2N(C(O)CH3)2. It is commonly used as a peroxide bleach activator in household detergents and for paper pulp. It is produced by acetylation of ethylenediamine. Although structurally and in abbreviation very similar to EDTA, the two compounds should not be interchanged.

Use in laundry detergents and mechanism of action[edit]

TAED is an important component of laundry detergents and bleaches, where it is used as an activator for "active oxygen" bleaching agents. Active oxygen bleaching agents include sodium perborate, sodium percarbonate, sodium perphosphate, sodium persulfate, and urea peroxide. These compounds release hydrogen peroxide during the wash cycle. Hydrogen peroxide is an inefficient bleach below 70 °C, but when activators such as TAED are present, hydrogen peroxide (in the form of the perhydroxyl anion in the alkaline water) can react with the bleach activator in a process called perhydrolysis to form a peroxy acid (also known as a peracid). Peroxy acids are more efficient at bleaching at lower temperatures. TAED was first used in a commercial laundry detergent in 1978 (Skip by Unilever).[1] Currently, TAED is the main bleach activator used in European laundry detergents and has an estimated annual consumption of 75 kt.[2]

In aqueous alkaline solution, the perhydroxyl anion HO2- (from hydrogen peroxide) reacts with TAED to form triacetylethylenediamine (TriAED) and diacetylethylenediamine (DAED) consecutively, and releases (roughly) two equivalents of peracetic acid (a peroxy acid), which is a fast-acting bleaching agent:[3]

Peracetic acid production from the hydrogen peroxide and TAED.svg

TAED, TriAED and DAED are all completely biodegradable and substantially removed during wastewater treatment.[4] Theoretically, the perhydrolysis of TAED could yield four moles of peracetic acid per mole of TAED, as there are four acyl groups present. However, a molecule of TAED can only provide a maximum of two equivalents of peracetic acid due to the substantial increase in the conjugate acid pKa of the leaving group going from an amide (pKa = 17) to an amine (pKa = 35).[5] Therefore, TAED can deliver a maximum of two equivalents of peracetic acid. However, due to a competing reaction of TAED with hydroxide anions (saponification), two equivalents is not quite achieved, and various values have been measured such as 1.5 mol[6] and 1.7 mol.[7]

References[edit]

  1. ^ Smulders E.,; von Rybinski W.,; Sung E.; Rähse W.; Steber J.; Wiebel F.; Nordskog A. (2002). "Laundry Detergents". Ullmann's Encyclopedia of Industrial Chemistry. Wiley-VCH. 
  2. ^ Reinhardt, G.; Borchers, G. (2009). "Application of Bleaching Detergent Formulations". In Zoller, Uri. Handbook of Detergents Part E: Applications. USA: CRC Press. ISBN 9781574447576. 
  3. ^ D. Martin Davies and Michael E. Deary "Kinetics of the hydrolysis and perhydrolysis of tetraacetylethylenediamine, a peroxide bleach activator" J. Chem. Soc., Perkin Trans. 2, 1991, pages 1549 - 1552. doi:10.1039/P29910001549.
  4. ^ Gilbert, P. A. (1992). "TAED-Tetraacetylethylenediamine". In de Oude, N. T. The Handbook of Environmental Chemistry, Vol. 3 Part F Antropogenic Compounds: Detergents. Berlin: Springer-Verlag. ISBN 354053797X. 
  5. ^ Farr, J. P.; Smith, W. L.; Steichen,, D. S. (1992). "Bleaching Agents". Kirk-Othmer Encyclopedia of Chemical Technology Vol. 4 (4th ed.). John Wiley & Sons, Inc. pp. 271–299. 
  6. ^ Hauthal, G. H., Schmidt, H., Scholz, J., Hofmann, J. and Pritzkow W. (1990). "Studies concerning the mechanism of bleach activation". Tenside Surf. Det. 27 (3). 
  7. ^ Hofmann, J., Just, G., Pritzkow, W. and Schmidt, H. (1992). "Bleaching activators and the mechanism of bleaching activation". J. Prakt. Chem.-Chem. Ztg. 334 (4): 293–297. 

See also[edit]