|Melting point||149 °C (300 °F; 422 K)|
|0.2 g/L @ 20ºC|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
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
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 60 °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 like 40 °C, . TAED was first used in a commercial laundry detergent in 1978 (Skip by Unilever). Currently, TAED is the main bleach activator used in European laundry detergents and has an estimated annual consumption of 75 kt.
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:
TAED, TriAED and DAED are all completely biodegradable and substantially removed during wastewater treatment. 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). 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 and 1.7 mol.
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