Bleaching of substrates
The present invention concerns the treatment of substrates with a preformed transition metal catalyst in an aqueous solution. The transitional metal catalyst is a dinuclear Mn transitional metal catalyst and its ligand has the following formula (I): and p is 3.
1. A method of treating a substrate comprising the following step:
contacting the substrate with an aqueous medium comprising at least 1% of water, from 1 to 1500 mM of hydrogen peroxide, and a preformed transition metal catalyst to form an oxidative medium; wherein the transition metal catalyst is a dinuclear Mn(II)Mn(II), Mn(II)Mn(III), Mn(III)Mn(III), Mn(III)Mn(IV) or Mn(IV)Mn(IV) transition metal catalyst having a ligand of formula (I):
p is 3;
R is independently selected from the group consisting of: hydrogen, C 1 -C 6 -alkyl, CH 2 CH 2 OH, CH 2 COOH, and pyridin-2-ylmethyl; and one of R is linked to the N of another Q from another ring via an ethylene bridge;
R 1 , R 2 , R 3 , and R 4 are independently selected from the group consisting of:
H, C 1 -C 4 -alkyl, and C 1 -C 4 -alkylhydroxy; and
wherein the oxidative medium has a pH in the range 11.2 to 12.8 and the concentration of the transition metal catalyst is in the range from 0.0005 to 0.08 microM.
2. The method according to claim 1 , wherein R is independently selected from: hydrogen, CH 3 , C 2 H 5 , CH 2 CH 2 OH and CH 2 COOH.
3. The method according to claim 1 , wherein R, R 1 , R 2 , R 3 , and R 4 are independently selected from: H and Me.
4. The method according to claim 1 , wherein the catalyst is derived from 1,2,-bis-(4,7,-dimethyl-1,4,7,-triazacyclonon-1-yl)-ethane (Me4-DTNE).
5. The method according to claim 4 , wherein the pH of the oxidative medium is from pH 11.2 to 12.8.
6. The method according to claim 4 , wherein the preformed transition metal catalyst salt is a dinuclear Mn(III) or Mn(IV) complex with at least one O 2− bridge.
7. The method according to claim 4 , wherein the substrate is selected from the group consisting of: cellulosic substrate, crockery.
8. The method of treating a substrate according to claim 1 , wherein the pH of the oxidative medium is from pH 11.5 and 12.5.
9. The method according to claim 1 , wherein the preformed transition metal catalyst salt is a dinuclear Mn(III) or Mn(IV) complex with at least one O 2− bridge.
10. The method according to claim 1 , wherein the preformed transition metal catalyst salt is a salt of the metal complex [Mn III Mn IV (μ-O) 2 (μ-CH 3 COO)(Me 4 -DTNE)] 2+ .
11. The method according to claim 1 , wherein the substrate is selected from the group consisting of: cellulosic substrate, crockery.
12. The method according to claim 11 , wherein the substrate is a cellulosic substrate or crockery.
13. The method according to claim 1 , wherein the treating of the substrate occurs in a mechanical dishwasher.