WO2003074645A1

WO2003074645A1 - Composition comprising macrocyclic tetra-amido n-donor metal-ligand complex as bleaching catalyst

Info

Publication number: WO2003074645A1
Application number: PCT/EP2003/001520
Authority: WO
Inventors: Stephen Norman Batchelor; Niels Ouwerkerk; Van Der Sebastiaan Velden; De Cornelis Hendrikus Vries; Angelique Jacqueline Brigitte Connie Wagenaar
Original assignee: Carnegie Mellon University
Priority date: 2002-03-06
Filing date: 2003-02-12
Publication date: 2003-09-12
Also published as: AR038865A1; AU2003205770A1; GB0205278D0

Abstract

The present invention relates to compositions comprising a macrocyclic tetra-amido N-donor metal-ligand complexes as a bleaching catalyst. It provides a laundry bleaching composition comprising: a) a macrocyclic tetra amido N-donor metal-ligand complex (preferably, 5,6-benzo-3,8,11,13-tetraoxo-2,2,9,9,12,12-hexamethyl-1,4,7,10- tetraaza-cyclo-tridecane), and b) a builder, said composition being substantially devoid of any added peroxygen bleach or a peroxy-based or peroxyl-generating bleach system.

Description

COMPOSITION COMPRISING MACROCYCLIC TETRA-AMIDO N-DONOR METAL-LIGAND COMPLEX AS BLEACHING CATALYST

Technical Field

The present invention relates to compositions comprising a macrocyclic tetra-amido N-donor metal-ligand complexes as a bleaching catalyst.

Background of the Invention Oxidation catalysts comprising metal -complexes are well known. Such catalysts have been proposed for use in laundry compositions as components of a bleaching system. These catalysts activate H₂O₂ or other peroxygen sources.

A particular catalyst is disclosed in WO 98/03263, filed 21 July 1997, (Collins) , which comprises a macrocyclic (tetra) amido N-donor. The macrocycle is capable of complexing with a metal ion, for example an iron III or IV. The complex also comprises axial ligands, for example as chloride or water, and one or more counter ions, for example tetraphenyl-phosphonium and tetraethylammonium.

One proposed purpose of these catalysts has been to assist in the bleaching of dyestuffs released from articles being laundered. If these dyestuffs are not removed from the wash liquor then they will re-deposit onto articles and cause a loss of colour definition or even catastrophic damage to 'white' articles. United States Patent 5,853,428, filed 24 Feb 1997, (Collins) discloses use of similar catalysts in laundry detergent compositions. In both these citations the addition of hydrogen peroxide, or a source thereof, is envisaged as a means of activating the catalyst.

Bleaching agents typically present in laundry detergents include percarbonates and/or perborates, which can also act as sources of hydrogen peroxide and/or other peroxyl species .

Bleaching catalysts capable of bleaching effectively in the absence of an added peroxyl sources have recently become the focus of some interest, for example: WO9965905; WO0012667; WO0012808; WO0029537, and, WO0060045. It is believed that these catalysts have the capability to use atmospheric oxygen as a source of oxidising equivalents.

Summary of the Invention

It is known from our co-pending GB application of 19 February 2002 that dyes can be decolourised by the macrocyclic tetra amido N-donor metal-ligand complex in the absence of added hydrogen peroxide provided that a commercial alkyl benzene sulphonate surfactant is present .

We have now determined that these complexes can bleach stains and reduce dye transfer in the absence of any added source of oxidising equivalents. Accordingly, the present invention provides a bleaching composition which comprises:

a) a macrocyclic tetra amido N-donor metal-ligand complex, and,

b) a detergency builder,

said composition being substantially devoid of any added peroxygen bleach or a peroxy-based or peroxyl-generating bleach system.

It is particularly advantageous to be able to bleach dyestuffs without the addition of hydrogen peroxide or a source thereof to the composition. Not only does this have savings in terms of cost, but it also removes some of the limitations on formulation which would be brought about by the presence of hydrogen peroxide. The present invention also dispenses with the need for a selected surfactant to be present.

The term "substantially devoid of any added peroxygen bleach or a peroxy-based or peroxyl-generating bleach system" should therefore be construed within the spirit of the invention. It is preferred that, other than as a component of the surfactant, the composition has as low a content of peroxyl species present as possible. Typically, the level of added peroxy compounds in the composition will be insufficient to generate less than O.OOlppm active oxygen. This is similar to the level of peroxy species found in rainwater. The present invention extends to a method of bleaching a substrate comprising applying to the substrate, in an aqueous medium, the bleaching composition according to the present invention.

The present invention extends to a commercial package comprising the bleaching composition according to the present invention together with instructions for its use.

The bleaching composition may be contacted to the textile fabric in any suitable manner. Typically, it will be applied as a wash liquor for laundry cleaning. In particular, the treatment may be effected in a wash cycle for cleaning laundry.

We have determined that with some dyes the bleaching effect is enhanced if the stains are exposed to real or simulated sunlight .

Any suitable textile that is susceptible to bleaching or one that one might wish to subject to bleaching may be used. Preferably the textile is a laundry fabric or garment.

In particular the treatment may be effected in, or as an adjunct to, an essentially conventional wash cycle for cleaning laundry. More preferably, the treatment is carried out in an aqueous detergent wash liquor. The bleaching composition can be delivered into the wash liquor from a powder, granule, pellet, tablet, block, bar or other such solid form. The solid form can comprise a carrier, which can be particulate, sheet-like or comprise a three-dimensional object. The carrier can be dispersible or soluble in the wash liquor or may remain substantially intact. In other embodiments, the bleaching composition can be delivered into the wash liquor from a paste, gel or liquid concentrate.

Delivery of the composition from a liquid concentrate confers certain specific advantages. In particular it is difficult to prepare stable liquid bleaching compositions for laundry. As the present invention is essentially catalytic in nature and the preferred catalysts are long- lived it is envisaged that the compositions will have excellent storage stability.

A unit dose as used herein is a particular amount of the bleaching composition used for a type of wash. The unit dose may be in the form of a defined volume of powder, granules or tablet .

Detailed Description of the Invention

In order that the invention may be further understood it is described below with reference to certain preferred features .

The Bleach Catalyst:

The amount of catalyst in the detergent composition is typically sufficient to provide a concentration in the wash liquor of generally 0.005 μm to 100 μm, preferably from 0.025 μM to 50 μM, more preferably from 0.05 μM to 10 μM. Preferred metal-complexed ligands are those having the structure as shown in general formula 1 :

General formula 1 :

wherein :

- Bi, B₃ and B₄ each represent a bridging group having zero, one two or three carbon containing nodes for substitution, and B₂ represents a bridging group having at least one carbon containing node for substitution, each said node containing a C (R) , C(Rχ) (R₂) or C (R) ₂ .

- each R substituent is the same is the same or different from the remaining R substituents, and

(i) is selected from the group consisting of alkyl , alkenyl, cycloalkyl, cycloalkenyl , aryl, alkynyl, alkylaryl, halogen, alkoxy, phenoxy and combinations thereof, or (ii) form a substituted or unsubstituted benzene ring of which two carbons on the ring form nodes in the B-unit ;

- M is a transition metal ion;

- L is an axial ligand; and,

- Q is an alkali metal or tetra-alkyl ammonium or tetra- phenyl phosphonium counter-ion.

Preferably, the axial ligand is selected from the group consisting of water and halide. Particularly preferred axial ligands are water and chloride.

It is within the scope of the present invention to have a bleach activator, wherein M is selected from the group consisting of Fe, Mn, Cr, Cu, Co, Ni, ^'Mo, V, Zn and W.

The most preferred catalyst is that in which the ligand is 5, 6-benzo-3, 8, 11, 13-tetraoxo-2 , 2 , 9, 9, 12, 12-hexamethyl- 1,4,7,10- tetraaza-cyclo-tridecane .

The axial ligand ^λL' is water or preferably chloride. The counter-ion 'Q' is preferably lithium. The ligand is also known as 3 , 4 , 8 , 9-tetrahydro-3 , 3 , 6 , 6, 9 , 9-hexa-methyl-lH- 1,4, 8,ll-benzotetraazocyclotridecane-2,5, 7, 10 (6H,11H) tetrone .

In addition t,o the catalyst it is possible to include an enhancer in the composition. Preferably the enhancers are nitrogen-containing organic molecules. More preferably, the enhancer compounds are of the general formula one, shown below:

General Formula One :

\ /

N- ^■N

/ \

wherein:

Zi and Z₂ are electron-withdrawing groups, independently selected from the group consisting of optionally substituted alkyl/ (hetero) (poly)aryl-, -sulfone, -sulfoxide, - sulfonate, -carbonyl, -oxalyl, -amidoxalyl, -hydrazidoxalyl, -carboxyl and esters and salts thereof, -amidyl, - hydrazidyl, and nitrile.

Z₃ and Z₄ are hydrogen, or are absent when the bonding between Z or Z₂ and the adjacent nitrogen in the general form is a pi-bond.

In preferred enhancers Z₃ and Z₄ are both hydrogen (thereby forming a hydrazino compound) , or Z₃ and Z₄ are both absent (thereby forming an azino compound) .

Particularly preferred azino enhancers are molecules of the general formula given below:

This molecule is known as 2 , 2 ' -Azino-bis (3 -ethyl- benzthiazoline-6-sulphonate) diammonium salt. Its CA registry number is 30931-67-0.

Preferred hydrazino enhancers may contain one or more than one of the hydrazino structures . The general formulae of two particularly preferred enhancers are given below:

'Dirner'

^lECHA'

The structure of a further enhancer, which does not have the characteristic azino- or hydrazino- bond of the preferred embodiments discussed above is given below:

This is phenothiazine-10-propionate (PTP) , as described in US-A-5 451 337 and US-A-5 445 755.

Builder;

The compositions of the invention contain a detergency builder. This is preferably present in an amount of from about 5 to 80 % by weight, preferably from about 10 to 60 % by weight .

Builder materials may be selected from 1) calcium sequestrant materials, 2) precipitating materials, 3) calcium ion-exchange materials and 4) mixtures thereof.

Examples of calcium sequestrant builder materials include alkali metal polyphosphates, such as; sodium tripolyphosphate; nitrilotriacetic acid and its water-soluble salts; the alkali metal salts of carboxymethyloxy succinic acid, ethylene diamine tetraacetic acid, oxydisuccinic acid, mellitic acid, benzene polycarboxylic acids, citric acid; and; polyacetal carboxylates as disclosed in US-A-4, 144 , 226 and US-A-4, 146,495.

Examples of precipitating builder materials include sodium orthophosphate and sodium carbonate .

Examples of calcium ion-exchange builder materials include the various types of water-insoluble crystalline or amorphous aluminosilicates, of which zeolites are the best known representatives, e.g. zeolite A, zeolite B (also known as zeolite P) , zeolite C, zeolite X, zeolite Y and also the zeolite P-type as described in EP-A-0, 384 , 070.

In particular, the composition may contain any one of the organic and inorganic builder materials, though, for environmental reasons, phosphate builders are preferably omitted or only used in very small amounts.

Typical builders usable in the present invention are, for example, sodium carbonate, calcite/carbonate, the sodium salt of nitrilotriacetic acid, sodium citrate, carboxymethyloxy malonate, carboxymethyloxy succinate and water-insoluble crystalline or amorphous alummosilicate builder materials, each of which can be used as the main builder, either alone or in admixture with minor amounts of other builders or polymers as co-builder. Surfactant

Typically the compositions of the invention will further comprise a surfactant.

A preferred surfactant comprises an alkyl benzene sulphonate. Suitable alkyl benzene sulphonate compounds which may be used are water-soluble alkali metal salts of organic sulphonates having alkyl radicals containing from about 8 to about 22 carbon atoms, the term alkyl being used to include the alkyl portion of higher acyl radicals. Particularly preferred surfactant compounds are sodium and potassium alkyl C₉-C₂₀ benzene sulphonates, particularly sodium linear secondary alkyl C₁₀-C₁₅ benzene sulphonates. The most preferred anionic detergent compounds are sodium C₁₁-C₁₅ alkyl benzene sulphonates.

Other surfactants may be present in the compositions of the invention. Preferably these are anionic surfactants. Examples of suitable synthetic anionic surfactants include: sodium and ammonium alkyl sulphates, especially those obtained by sulphating higher (Cβ-Ciβ) alcohols produced, for example, from tallow or coconut oil; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow or coconut oil fatty acid mono-glyceride sulphates and sulphonates; sodium and ammonium salts of sulphuric acid esters of higher (C₉-C₁₉) fatty alcohol alkylene oxide, particularly ethylene oxide, reaction products; the reaction products of fatty acids such as coconut fatty acids esterified with isethionic acid and neutralised with sodium hydroxide; sodium and ammonium salts of fatty acid amides of methyl taurine; alkane mono-sulphonates such as those derived by reacting alpha-olefins (C₈-C₂₀) with sodium bisulphite and those derived by reacting paraffins with SO₂ and CI₂ and then hydrolysing with a base to produce a random sulphonate; sodium and ammonium (C₇-C₁₂) dialkyl sulphosuccinates; and; olefin sulphonates, which term is used to describe material made by reacting olefins, particularly (C₁₀-C₂₀) alpha-olefins, with SO₃ and then neutralising and hydrolysing the reaction product.

The compositions of the invention may also comprise nonionic surfactants. As will be discussed below, the nonionic surfactants do not appear to act as substrates for the catalyst. Moreover, it is believed that even in the presence of anionic surfactant the catalysts become less effective as the level of nonionic is increased. However low levels of nonionic surfactants can be present to confer cleaning benefits .

Examples of suitable nonionic surface-active compounds which may be used, preferably together with the anionic surface- active compounds, include, in particular; the reaction products of alkylene oxides, usually ethylene oxide, with alkyl (C₆-C₂₂) phenols, generally 5-25 EO, i.e. 5-25 units of ethylene oxides per molecule; and; the condensation products of aliphatic (Cs-Cie) primary or secondary linear or branched alcohols with ethylene oxide, generally 2-30 EO.

Other so-called nonionic surface-actives include alkyl polyglycosides, sugar esters, long-chain tertiary amine oxides, long-chain tertiary phosphine oxides and dialkyl sulphoxides .

Preferably the surfactant is present in the composition in an amount such that a unit dose provides at least 0.05, more preferably 0.1, most preferably 0.2 g/1 concentration of the surfactant compound in a wash.

Other Components :

It is advantageous for the compositions of the invention to comprise at least one nitrogen-containing, dye binding, DTI polymers. Of these polymers and co-polymers of cyclic amines such as vinyl pyrrolidone, and/or vinyl imidazole are preferred. Suitable polymers include polyvinyl pyrrolidone polymers, polyamine N-oxide polymers, copolymers of

N-vinylpyrrolidone and N-vinylimidazole, and polymers of N-carboxymethyl-4-vinylpyridinium chloride. Most preferably the composition according to the present invention comprises a dye transfer inhibition agent selected from poly vinyl- pyrridine N-oxide (PVPy-NO) , polyvinyl pyrrolidone (PVP) , polyvinyl imidazole, N-vinylpyrrolidone and N-vinylimidazole copolymers (PVP/PVI) , copolymers thereof, and mixtures thereof .

The amount of dye transfer inhibition agent in the composition according to the present invention will be from 0.01 to 10 %, preferably from 0.02 to 5 %, more preferably from 0.03 to 2 %, by weight of the composition.

Apart from the components already mentioned, the composition can contain any of the conventional additives in amounts of which such materials are normally employed in fabric washing detergent compositions.

Examples of these additives include; buffers such as carbonates; lather boosters, such as alkanolamides, particularly the monoethanol amides derived from palmkernel fatty acids and coconut fatty acids; lather depressants, such as alkyl phosphates and silicones; anti-redeposition agents, such as sodium carboxymethyl cellulose and alkyl or substituted alkyl cellulose ethers; stabilisers, such as phosphonic acid derivatives (i.e. Dequest^® types) ; fabric softening agents; inorganic salts and alkaline buffering agents, such as sodium sulphate and sodium silicate; and, usually in very small amounts, fluorescent agents; perfumes; enzymes, such as proteases, cellulases, lipases, amylases and oxidases; germicides and colourants. In order that the invention may be further and better understood it will be described in detail with reference to following non-limiting examples:

Examples

The catalyst referred to in the examples is the Fe complex of 3,4,8, 9-tetrahydro-3,3, 6,6,9, 9-hexamethyl-lH-l, 4 , 8,11- benzo-tetraazocyclotri-decane -2,5,7,10 (6H,11H) tetrone, with lithium as the counter-ion and water as the axial ligand. This was synthesised in accordance with the method set out in our co-pending patent application GB 0020846.2.

Example 1

A solution of crocetin, a water soluble carotenoid was made in water, such that the optical absorbance at 420nm, 1cm path-length was 1.36. The aqueous solution was buffered to pH 10.5 using standard salts (sodium carbonate, sodium bicarbonate and sodium phosphate) .

The solution was divided into two aliquots and to one catalyst was added such that it solution concentration was 0.72 micromolar. After 1000s the absorbance of both solutions was measured and is given in table 1.

Table 1

From these results bleaching of the crocetin by the catalyst is seen. While more rapid results can be obtained by adding a peroxygen compound, these results show that bleaching of a stain in solution can be obtained in the absence of any added peroxygen compounds .

Example 2

A solution of circumin, was made in water, such that the optical absorbance at 420nm, 1cm path-length was 0.66. The aqueous solution was buffered to pH 10.5 using standard salts .

The solution was divided into several aliquots and different concentrations of catalyst were added. 1000s after addition of catalyst the absorbance of the solutions was measured and results are given in table 2.

TABLE 2

Bleaching of the circumin in solution by the catalyst is again seen in the absence of added peroxy compounds. It can be seen that there is a clear relation between the level of catalyst added and the degree of bleaching over time.

Example 3

Saturated solutions of the spice turmeric were made in (a) olive oil and (b) a 50:50 mixture of water and propan-2-ol The solution were used to make stains on cotton cloth by placing 5 drops of the required solution onto a 9 by 9 cm piece of woven cotton.

The so-formed stains were left to age for 2 hours then washed as follows:

(i) in water buffered to pH 10 using standard salts

(ii) in water buffered to pH 10 using standard salts and with 1 micromolar of catalyst added.

Washes were conducted at 25°C in 250 ml of solution. Two of each type of stained cloths, and 2 clean white ballast cloths were placed in the wash liquor and the solution agitated for 30 minutes. Following this the clothes were rinsed in a dilute solution of HCl ( approx. O.OOlMolar) and then in cold water, then placed in a tumble dryer for 20 minutes to dry.

The staining of all the cloth in the wash relative to clean white cloth was then measured using a reflectance spectrometer and expressed as ΔE values. The average values observed are given in table 3.

TABLE 3

From these results it can be seen that stain removal was improved by the presence of the catalyst without added peroxy compounds. Moreover, the catalyst alone is sufficient to significantly reduce the extent of stain transfer to the white monitor cloth.

Example 4

A saturated solution of the spice turmeric was made in olive oil. A solution of the carotenoid -carotene in olive oil was made by dissolving 0.005g of the carotenoid in 25g of oil .

The oil solutions were used to make stains on cotton cloth by placing 1 drops of the required solution onto a 9 by 9 cm piece _.of woven cotton. The so-formed stains were left to age for 1.5 hours then washed as follows :

(i) in water buffered to pH 10 using standard salts

(ii) in water buffered to pH 10 using standard salts and with 2 micromolar catalyst added.

Washes were conducted at 40°C in 300 ml of solution. Three of each type of stained cloths, and three clean white ballast cloths were placed in the wash liquor and the solution agitated for 30 minutes. Following this the clothes were rinsed in a dilute solution of HCl ( approx. O.OOlMolar) and then in cold water, then placed in a tumble dryer for 20 minutes to dry.

The staining of all the cloth in the wash relative to clean white cloth was then measured using a reflectance spectrometer and expressed as ΔE values. The average values observed are given in table 4.

TABLE 4

From these results it can be seen that stain removal from was improved by the presence of the catalyst without added peroxy compounds. It can also be seen that stain pick-up by the white ballast has been significantly reduced in the presence of the catalyst .

Example 5

Example 3 was repeated except here the wash solution were

(i) water plus 2g/l Wisk™,

(ii) water plus 2g/l Wisk™ + 1 micromolar of catalyst.

Wisk™ (ex Lever Bros. USA) is a laundry detergent which does not contain any bleaching components

The results are given in table 5

TABLE 5

From these results it can be seen that stain removal from of the cloth was significantly improved by the presence of the catalyst/detergent without added peroxy compounds. The data for the pick up on the white monitor cloth shows that dye transfer was reduced in the presence of the catalyst.

Example 6

Stained cloth were created by the method of example 3 and washed in Wisk detergent as in example 5.

1 ml of 2 micromolar catalyst solution at pH 10 was pipetted onto the clothes and left for 30 minutes. To a separate set of equivalent cloths 1ml of water at pH 10 was added and left for 30 minutes, rinsed in a dilute solution of HCl (approx. O.OOlMolar) and then in cold water, then placed in a tumble dryer for 20 minutes to dry.

The ΔE of the clothes relative to white cloth were then measured. For the stain created from turmeric in water/propan-2-ol the staining was measured in the centre and at the edge of the cloth, as there was a clear difference. Average values are given in table 6. TABLE 6

In the case of the staining by turmeric/oil and at the edge of the turmeric/alcohol stain, stain removal was significantly improved by the presence of the catalyst without added peroxy compounds .

Example 7

Olive oil/turmeric stains were made on woven cotton using the method of Example 3 , except here 3 drops of the oil was placed onto each cloth and then aged for 5 days in the dark. The stains were then washed as per Example 3, except 4 stained, 4 clean white cloths and 210 ml of water was used per wash. 2 of the washed stained clothes were place in a Weatherometer™, which simulates Florida sunlight, and irradiated for 30 minutes. The other clothes were dried in a tumble dryer. Following this the residual staining of the cloths were measured as ΔE values relative to clean cloth and the average values are given in Table 7 TABLE 7

From these results it can be seen that stain removal is significantly increased and stain transfer is significantly reduced by the presence of the catalyst and without added peroxy compounds. Furthermore on exposure to simulated sunlight the benefit over the control becomes even greater.

Example 8

Solutions of the azo dyes Orange I and Orange II were made in water buffered to pH 10 using standard salts. The solutions were divided into 2 aliquots and the aliquots treated as follows:

(i) irradiated in a Weatherometer for 30 minutes in a glass jar

(ii) 3 micromolar of the catalyst added and then irradiated as per (i) Following the treatment the absorbance of the solution were measured on a UV-VIS spectrometer (1cm path-length) , and the results presented in Table 8.

TABLE 8

Addition of the catalyst and irradiation leads to bleaching of the dye without addition of peroxy compounds. (Control experiments showed that addition of catalyst without irradiation did not bleach these 2 dyes)

Example 9

A 0.05% solution of circumin in soybean oil/acetone (1:19) was made and cotton cloth was stained by dipping into this solution. Stains were washed for 30 minutes with 5g/l of a model washing powder (11.4% sodium LAS, 13.0% non ionic surfactant 7EO, 55.5% salts (sodium tri-polyphosphate, and silicate), minors 5%, remainder water) at 60 C. To one wash

1 micromolar catalyst was added.

The decrease in staining of the cloth following treatment was 24 and 35 ΔE units for the wash and wash with catalyst respectively. Thus the catalyst significantly increases the stain removal in the absence of added peroxy compounds .

Example 10

o

The experiments of Example 9 were repeated at 40 C using model washing powders created from:

(a) sodium LAS plus salts, and,

(b) sodium LAS plus nonionic plus zeolite

Improved stain removal benefits were found when the catalyst was added such that its concentration in solution was 0.05 to 5 micromolar.

Claims

1. A bleaching composition comprising:

a) a macrocyclic tetra amido N-donor metal-ligand complex, and,

b) a detergency builder.

said composition being substantially devoid of any added peroxygen bleach or a peroxy-based or peroxyl- generating bleach system.

2. A bleaching composition according to claim 1, wherein alkyl benzene sulphonate surfactant is present in the composition in an amount sufficient to provide a concentration in a wash liquor of at least 0.05 g/1.

3. A bleaching composition according to claim 1, wherein the macrocyclic tetra amido N-donor metal-ligand complex catalyst is present in the composition in an amount sufficient to provide a concentration in a wash liquor of 0.005 μm to 100 μm.

4. A bleaching composition according to claim 1 wherein the metal-ligand is that having the structure as shown below:

wherein:

Bi, B₃ and B₄ each represent a bridging group having zero, one two or three carbon containing nodes for substitution, and B₂ represents a bridging group having at least one carbon containing node for substitution, each said node containing a C(R), C(Rι) (R₂) or C (R) ₂

each R substituent is the same is the same or different from the remaining R substituents, and

(i) is selected from the group consisting of alkyl, alkenyl, cycloalkyl, cycloalkenyl, aryl, alkynyl, alkylaryl, halogen, alkoxy, phenoxy and combinations thereof, or

(ii)form a substituted or unsubstituted benzene ring of which two carbons on the ring form nodes in the B- unit ; M is a transition metal ion; L is an axial ligand; and,

Q is an alkali metal or tetra-alkyl ammonium or tetra-phenyl phosphonium counter-ion.

5. A bleaching composition according to claim 4 wherein the axial ligand is selected from the group consisting of water and halide.

6. A bleaching composition according to claim 4 wherein M is selected from the group consisting of Fe, Mn, Cr, Cu, Co, Ni, Mo, V, Zn and W.

7. A bleaching composition according to claim 4 wherein the ligand is 5 , 6-benzo-3 , 8 , 11, 13-tetraoxo-

2,2 , 9, 9, 12, 12-hexamethyl-l,4, 7, 10- tetraaza-cyclo- tridecane .