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Ligand salts
Metal-free bleach boosters for laundry applications

GERD REINHARDT*, MICHAEL BEST AND INA HERRGEN
*Corresponding author
WeylChem Wiesbaden GmbH, Industriepark Hoechst, Building D 562, 65926 Frankfurt am Main, Germany

Abstract

Salts derived from 1,4,7-triazacyclononane are seen as volume effective substitutes for common bleach activators which provide insufficient bleaching power at cold temperatures. It is assumed that such ligand salts (ls) react with polyphenolic compounds and metal ions present in stains to form redox active complexes which, in the presence of hydrogen peroxide, bleach the surrounding area. Catalytic amounts of ligand salts show excellent bleaching power on tea, red wine and fruit stains in the temperature range of 20 to 40°C. Tested on more than 100 dyes, on average, the system is gentler than common bleach activators. Their chemical inertness allows the use of ligand salts in solid or liquid formulations, even in the presence of hydrogen peroxide.


INTRODUCTION

Teas, juices and fruit-based products are gaining popularity as they are seen essential for healthier life. They are rich in polyphenolic compounds (flavonoids and tannins) which provide antioxidation properties and are valuable sources of dietary minerals. However, when spilled on fabrics; fruit, tea and red wine stains are often difficult to remove. Although in general water soluble, polyphenols are washed out easily only when fresh. In aging processe s those stains are fixed to fibres and chemical oxidation reactions are required get clean clothes. For this purpose, European laundry powder detergents normally contain an activated bleach system, e.g. Tetraacetyl ethylenediamine (TAED) combined with sodium percarbonate (SPC). The generated peroxyacetic acid oxidizes coloured phenolic compounds effectively in the 40 to 60°C range. Unfortunately, the TAED system is less reactive at lower temperatures; here the bleaching reaction is kinetically slowed down.

Longer reaction times, more chemistry or alternative systems are required to fill this gap and to satisfy consumer needs in order to achieve effective low temperature bleach perfor ...




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