DE69020380T2 - Metal porphyrins for use as bleaching catalysts. - Google Patents

Description

The present invention relates to improved metalloporphyrins for use as bleach catalysts in fabric bleaching and to fabric cleaning and bleaching compositions comprising the metalloporphyrins.

It is known that metal porphyrins can act as oxidation catalysts. WO 88/07988 describes the use of metal porphyrins as catalysts in a variety of oxidation reactions. US-PS-4 077 768 describes the use of iron porphyrins with an oxidizing bleaching agent, for example hydrogen peroxide and also peracids, in aqueous wash liquids for dye bleaching in solution, ie for inhibiting dye transfer during the washing of fabrics. Furthermore, it is known from EP-A-0 306 089 (published March 8, 1989) that metal porphyrins can effectively catalyze the fabric stain bleaching action of peroxyacid bleach systems under mild conditions, thereby allowing the peroxyacid to be used more effectively in washing fabrics at lower temperatures between about 10°C and 40°C. A disadvantage of metal porphyrins as bleach catalysts is that they are themselves unstable to oxidation by the oxidizing bleach. Although the mode of action of metal porphyrin bleach catalysis is not fully known, the metal porphyrin catalyst appears to form an intermediate in the presence of an oxidizing bleach. This intermediate can react with substances that can be oxidized and bleached, thereby reforming the catalyst. This is the desired reaction. However, the intermediate can also react with a second metal porphyrin to form a dimeric oxo-bridged species that is ineffective as a bleach and decomposes rapidly under the oxidative conditions. Reaction of the metal porphyrin with hydrogen peroxide in the absence of a substrate leads to degradation by a different pathway, probably involving radicals. It is therefore necessary that careful measures be taken to avoid oxidation of the metal porphyrins. When bleaching fabrics with peroxyacids, the prior art teaches that metal porphyrins must be pre-adsorbed on the fabric in order to exert their catalytic activity in spot bleaching. Even in this case, some loss of catalyst due to decomposition with a consequent reduction in catalytic activity cannot be avoided.

The present invention now relates to improved metalloporphyrins as peroxyacid bleach catalysts which are more stable to oxidation by monooxygen donor type oxidants (such as peroxyacids, hypochlorite and tert-butyl hydroperoxide) than the metalloporphyrins proposed in the relevant art for use in fabric bleaching.

The metal porphyrins for use as a peroxyacid bleach catalyst in bleaching fabrics according to the present invention are compounds of the following structural formula:

wherein Me represents a metal ion selected from Mn(III) and Fe(III) and Ar represents a substituent selected from the group

with n and m each equal to 0 or 1 (provided that in the above formula (b), when n=m=0, the nitrogen atom is uncharged), A equal to a sulfate, sulfonate, phosphate or carboxylate group, B equal to C₁-C₁₀-alkyl, polyethoxyalkyl or hydroxyalkyl (when m=0 and in the formula (c)) or C₁-C₁₀-alkylene, polyethoxyalkylene or hydroxyalkylene (when m=1) and X₁ and X₂ equal to Cl, Br, CH₃, C₂H₅ or CH₃O

and

is selected.

Although not essential, the porphyrin core formula (I) may be substituted at one or more of the remaining carbon positions designated by the numbers 1-8, for example, by C₁-C₁₀ alkyl, hydroxyalkyl or oxyalkyl groups.

The phenyl or pyridyl group (a), (b) or (c) may optionally contain further substituents, but it has been found that improved stability is only achieved if the substituents X₁ and X₂ are bonded to the phenyl or pyridyl group exactly at the indicated locations near the porphyrin core. The substituents X₁ and X₂ bonded to other locations on the phenyl or pyridyl group, for example:

have no effect on stability.

Preferred molecules are those in which the substituents -(B)n-(A)m on the phenyl or pyridyl groups are selected from -CH3, -C2H5, -CH2-CH2-CH2-SO3-, -CH2CH(OH)CH2SO3- and -SO3-.

Preferably, X₁ and X₂ are Cl, Br or CH₃, in particular Cl or CH₃.

Typical examples of preferred Fe(III) and Mn(III) porphyrins are thus compounds in which the Ar substituents are the following residues:

The metalloporphyrins of the invention can be used as a catalyst for peroxyacids or peroxyacid salts for bleaching fabrics in a manner similar to that used for metalloporphyrins known in the art, but it will be readily appreciated that the improved stability of the metalloporphyrins of the invention will result in more effective and efficient use of the catalyst.

A general method of using metal porphyrins as a catalyst in bleaching and scouring fabrics with a peroxyacid or peroxyacid salt is to treat the fabrics with the metal porphyrin compound, leave the fabric in contact therewith for a predetermined time to cause sufficient adsorption of the compound onto the fabric, and then wash the fabric with a peroxyacid bleach composition. The fabrics may be treated in a bath comprising an effective amount of a dissolved or partially dissolved metal porphyrin (normally in the range of 2 to 25 ppm) for several minutes, followed by addition to the bath of a peroxyacid bleach in a concentration sufficient to cause the in an amount sufficient to achieve the desired bleaching effect (normally in an amount of about 20 to 1000 ppm). The amount of dissolved or partially dissolved metal porphyrin in the bath and also the amount of peroxyacid bleach added will depend on the fabric wash load and the dyeing rate, and their adjustment is within the skill of the person skilled in the art.

An alternative way of pre-treating the fabrics consists in manually applying it to the fabric on areas with persistent and stubborn stains, leaving the treated fabric for several minutes and then washing the fabric in a conventional manner with a peroxyacid bleach composition.

It should be noted that the tissues treated in a bath containing a dissolved or partially dissolved metal porphyrin may, if necessary, be manually pretreated with metal porphyrin.

The peroxyacids whose activity can be catalyzed by the metal porphyrins of the invention include any organic peroxyacids and inorganic peroxyacid salts.

Examples of such organic peroxyacids are compounds of the general formula:

HO-O- -(O)n-R-Y

wherein R represents an alkylene or substituted alkylene group having 1 to 20 carbon atoms or an arylene group having 6 to 8 carbon atoms, n represents 0 or 1 and Y represents hydrogen, halogen, alkyl, aryl or any group which provides an anionic moiety in aqueous solution, for example

with M being H or a water-soluble salt-forming cation.

The organic peroxyacids and salts thereof may contain either one, two or more peroxy groups and may be either aliphatic or aromatic. When the organic peroxyacid is aliphatic, the unsubstituted acid may have the following general formula:

HO-O- -(O)n-(CH₂)m-Y

where:

and

m is an integer from 1 to 20.

Specific examples of compounds of this type are peracetic acid, perlauric acid and diperoxydodecanedioic acid.

If the organic peroxyacid is aromatic, the unsubstituted acid may have the following general formula:

HO-O- -(O)n-C�6H₄-Y

where:

Y for example hydrogen, halogen, alkyl,

The percarboxy or percarboxylic acid and Y groups can occupy any relative position around the aromatic The ring and/or the Y group (in the case of alkyl) may contain any non-interfering substituents, for example halogen or sulfonate groups.

Specific examples of such aromatic peroxyacids and salts thereof are peroxybenzoic acid, m-chloroperoxybenzoic acid, p-nitroperoxybenzoic acid, p-sulfonatoperoxybenzoic acid, diperoxyisophthalic acid and peroxy-alpha-naphthol acid.

A specific example of inorganic peroxyacid salts is potassium monopersulfate. A product comprising this compound is the triple salt K2SO4 KHSO4 2KHSO5, which is available under the trade name Oxon from E.I. Dupont de Nemours and Company.

Accordingly, the present invention provides the use of a metalloporphyrin of structural formula (I) as defined above as a bleach catalyst for bleaching fabrics with a peroxyacid bleach system.

The present invention further provides a fabric washing product comprising a detergent active material, a peroxyacid bleach and the metal porphyrin as a catalyst therefor.

Fabric washing products according to the invention can be presented in any form, including that of a sachet of washing powder containing the metal porphyrin catalyst together with a separate package of a single-use sachet containing the peroxyacid.

Alternatively, the product may be in the form of a sachet in a sachet, the inner sachet containing a peroxyacid and being designed by a measure to ingredients with a delayed release, and the outer sachet contains a washing composition comprising the metal porphyrin catalyst and releases its ingredients fairly rapidly upon immersion in water.

Another product form is, for example, that of a washing powder comprising a peroxyacid and the metal porphyrin catalyst, in which the peroxyacid is provided in the form of coherently coated particles. Other product forms are possible, so that the person skilled in the relevant field has no difficulty in selecting product forms using existing technology.

In a further embodiment, the present invention provides a pretreatment product for topical application to fabrics, textiles and clothing consisting essentially of a liquid or pasty composition comprising a dispersion or solution of a metal porphyrin as defined above in a suitable liquid or semi-liquid carrier, presented for manual application in a suitable dispenser of any known applicator form, for example an aerosol pressure container, a pump spray container, a roller ball cap container, pad applicators and the like. In such applicators, the liquid carrier also contains a volatile solvent which evaporates on application, leaving the metal porphyrin firmly adhering to the fabric surface upon absorption. An example of a suitable carrier is a mixture of a non-ionic surfactant and a lower alcohol, for example methanol.

The compositions of the invention comprising metal porphyrins dispersed in a carrier of this type are typical for a roller ball lidded jar and pad applicators. Liquid or pasty compositions for use in A pretreatment product may contain about 0.1 to 1.0 g/l, typically about 0.2 to 0.5 g/l, of metalloporphyrin.

The treatment bath and the washing composition with the metal porphyrin catalyst can contain any of the usual components of cleaning compositions in the usual amounts. Thus, organic cleaning active materials of the anionic, non-ionic, zwitterionic and cationic type and mixtures thereof can be present in an amount of about 3 to about 40% by weight.

Suitable detergent actives are well known in the art. Examples of such suitable compounds commonly used in the art can be found in "Surface Active Agents", Volume I by Schwarz and Perry (Interscience 1949) and "Surface Active Agents", Volume II by Schwarz, Perry and Berch (Interscience 1958).

Inorganic or organic, phosphate or non-phosphate, water-soluble or non-water-soluble detergency builders and other water-soluble salts and buffering agents may preferably also be present. In addition, the washing composition may contain any other non-interfering ingredients normally used in detergent compositions which serve to improve the bleaching and washing properties of the composition or which contribute to an aesthetic appearance of the composition, in minor amounts. Such minor ingredients may be complexing agents and co-builders (for example homo- and copolymers), soap foam control agents, soil suspending agents and re-deposition preventing agents, enzymes, in particular proteolytic and lipolytic enzymes, corrosion inhibitors, optical brighteners, colorants, fragrances, clays and fillers.

Fabric washing compositions suitable for use in the present invention may contain from about 3 to about 40% by weight of an organic detergent active material, from 0 to 60, preferably from 5 to about 40% by weight of detergency builder, from about 1 to 10% by weight of peroxyacid and from about 0.05 to 1.0% by weight of metal porphyrin. They can typically be used at a dosage of from 2 to 10 g/l for washing fabrics in wash loads of from about 4 to 5 kg.

The invention is illustrated below by the following non-limiting examples.

Example I Preparation of metal porphyrins according to the invention (i) Tetrakis-(2,4,6-trimethyl-3-sulfonatophenyl)-porphyrinato-Mn(III)OH⁴-(Na⁺)⁴

0.5 ml of boron trifluoride etherate are added to 2.14 g of pyrrole (0.02 mol) and 2.96 g of 2,4,6-trimethylbenzaldehyde dissolved in 3 l of dichloromethane (dry). After stirring for 24 hours under argon in the dark, the mixture is refluxed for 30 min in the presence of 15 g of chloranil (0.06 mol). After concentrating the mixture, it is chromatographed on alumina using chloroform as eluent. The fractions containing porphyrin are collected and evaporated. Tetrakis-(2,4,6-trimethylphenyl)-porphyrin is obtained from the residue by crystallization from hexane. Treatment of this porphyrin with concentrated sulfuric acid yields tetrakis-(2,4,6-trimethyl-3-sulfonato)-porphyrin in the form of its four atropisomers. Stirring the latter in aqueous Mn-acetate (1M), subsequent treatment with an ion exchanger (Dowex 50 WH-form) and final neutralization yields compound (i). This is purified by chromatography on a Sephadex L H-20 column in methanol and obtained in a yield of 0.8 g (20%).

The system is characterized by UV/VIS, IR and FAB mass spectrometry.

(ii) Tetrakis-(2,4,6-trimethyl-3-sulfonatophenyl)porphyrinato-Fe(III)OH⁴⁻⁻ (Na+)₄

This system is prepared in a similar manner to that described above under (i), except that now a metalation was carried out using FeSO4. This gave compound (ii) in an amount of 0.3 g (7% yield). The compound is characterized in a similar manner as described for the manganese porphyrin.

Example II

The oxidative stability of the substituted manganese porphyrin of Example I (i) (TMP⁴⁻) against potassium monopersulfate (HSO₅⁻) and peracetic acid (per-Ac) was determined and compared with that of a non-substituted manganese porphyrin (TPP⁴⁻). Ar substituents:

The stabilities were determined using a UV/VIS spectroscopy method in the absence of a substrate at a catalyst concentration of 10⁻⁶ mol/l.

The results are shown in the following table. Table 1 Stability values from tests with HSO₅⊃min; (3.8 x 10⊃min;³ mol/l) Time (min) Table 2 Stability values from tests with Per-Ac (2.4 x 10⊃min;³ mol/l) Time (min)

From the above tables it is clearly evident that the inventive TMP⁻⁻ is more stable towards peracetic acid and potassium monopersulfate than the known TPP⁻⁻. Expressed in units of half-life, TMP⁻⁻ is about 20 times more stable towards HSO₅ and about 75 times more stable towards acetic acid compared to TPP⁻⁻.

Claims (9)

1. Use of a metal porphyrin of the following structural formula: wherein Me represents a metal ion selected from Mn(III) and Fe(III) and Ar represents a substituent selected from the group with n and m each equal to 0 or 1 (however, in formula (b) above, when n=m=0, the nitrogen atom is uncharged), A equal to a sulfate, sulfonate, phosphate or carboxylate group, B is C₁-C₁₀ alkyl (when m=0 and in formula (c)) or alkylene (when m=1), polyethoxyalkyl (when m=0 and in formula (c)) or alkylene (when m=1) or hydroxyalkyl (when m=0 and in formula (c)) or alkylene (when m=1) and X₁ and X₂ are Cl, Br, CH₃, C₂H₅ or CH₃O and is selected, as a peroxyacid bleach catalyst in the bleaching of fabrics. 2. Use according to claim 1, characterized in that the substituent -(B)n-(A)m is selected from -CH₃, -C₂H₅, -CH₂-CH₂- CH₂-SO₃-, -CH₂CH(OH)-CH₂-SO₃- and -SO₃⊃min; . 3. Use according to claim 1 or 2, characterized in that X₁ and X₂ are Cl, Br or CH₃. 4. A fabric washing composition comprising a detergent active material, a peroxyacid bleach and a metal porphyrin of the structural formula (I) according to claim 1. 5. A fabric washing composition according to claim 4, characterized in that the substituent -(B)n-(A)m is selected from -CH3, -C2H5, -CH2-CH2-CH2-SO3-, -CH2-CH(OH)-CH2-SO3- and -SO3-. 6. A fabric washing composition according to claim 4 or 5, characterized in that X₁ and X₂ are Cl, Br or CH₃. 7. Pretreatment product for local application to fabrics, textiles and clothing consisting essentially of a liquid or pasty composition with a dispersion or solution of a metal porphyrin of the structural formula (I) according to claim 1 in a suitable liquid or semi-solid carrier, which is presented in a suitable dispenser for manual application. 8. Pretreatment product according to claim 7, characterized in that the substituent -(B)n-(A)m is selected from -CH3, -C2H5, -CH2-CH2-CH2-SO3-, -CH2-CH(OH)-CH2-SO3- and -SO3-. 9. Pretreatment product according to claim 7 or 8, characterized in that X₁ and X₂ are Cl, Br or CH₃.