NO885571L - PORFYRINES, THEIR SYNTHESIS AND USE. - Google Patents

Abstract

Tetraphenylporphyrins which are β-substituted by fluorine or chlorine and / or carry electronegatyl substituents on phenyl including one or two solubilizing substituents. The new porphyrins are particularly suitable as catalysts in a variety of oxidation reactions and methods.

Description

Porphyrins, their syntheses and applications.

The application is a partial continuation of US patent application serial no. 039,566 filed April 17, 1987.

Certain metal-containing porphyrin compounds are known to be useful as chemical reagents of a catalytic nature, more particularly in directing certain oxidation processes. A biomimetic compound is a compound that mimics the activity of a biological compound. Certain porphyrins have been investigated for their ability to mimic the class of enzymes known as ligninase which participate in the natural process of wood degradation and modification by acting on lignin. The activity of these porphyrins on lignin model substrates has also been suggested by researchers.

Known porphyrins have been considered to suffer from certain deficiencies in that they are insufficient in the combination of properties desirable for many possible applications, such as e.g. within the cellulose and paper industry. Included among the observed problems with porphyrins is the problem of instability, which is often due to the ability of one porphyrin to adversely affect another. The efficiency of oxidation reactions must also be taken into account. For many important potential applications, water solubility is also combined with other desired properties, something that is particularly sought after.

Brief summary of the invention.

The present invention provides new and improved metal-containing porphyrin compounds, improved processes for their preparation and their use. Included among the new porphyrins are those that combine stability, high oxidation potential and water solubility.

Part of this invention provides porphyrins containing a contained number of chlorine and fluorine groups which increase the oxidation potential to an unexpectedly high level. Porphyrinfor bonds according to the invention are active in a wide variety of reactions.

An important group of reactions includes or relates to oxidation of lignin and lignin model compounds. Other reactions that they catalyze include the conversion of alkanes to alcohols and the conversion of alkenes to epoxides. Furthermore, they are able to oxidize organic environmental pollutants such as e.g. chlorinated biphenyls and dioxin into harmless compounds.

Detailed description of the invention.

The porphyrins according to the invention have the following formula I:

wherein M is a transition metal capable of undergoing oxidation, and which, if desired, can also be united to one or more ligands in addition to the four nitrogen groups, each Y and Y° is independently H, fluorine or chlorine, each ring R is wherein X and X° are independently H or an electronegative group which is not a water-solubilizing group, e.g. X and X° are independently fluorine, chlorine, bromine, or NO2, X^, X2 and X3 are independently H or an electronegative group, including water-solubilizing electronegative groups, which include without limitation fluorine, chlorine, bromine, SO3H, COOH or NO2, with the condition that 1) when none of X^, X2 and X3 is a water-solubilizing group, at least one Y and Y° on each five-membered ring has a meaning other than H, 2) when Y and Y° are both H, at least one but not more than two of X 1 , X 2 and X 3 a water-solubilizing group, e.g. SO3H or COOH, and at least two of X and X° and X^, X2 and X3 which is not a water-solubilizing group is independently an electronegative group which is not a water-solubilizing group, e.g. fluorine, chlorine, bromine or NO2, and 3) no more than two of X^, X2 and X3 are water-solubilizing groups,

or water-soluble salts thereof in which the aforementioned water-solubilizing groups are in a corresponding water-soluble salt form.

Special subgroups of the compounds of formula I are the compounds of formula Ia and Ib.

The compounds of formula Ia are those with reference to structural formula I in which: a) at least one of Y and Y° on each porphyrin ring is fluorine or chlorine and the other is H, fluorine or chlorine,

b) X and X° are independently H, fluorine, chlorine, bromine or NO2,

c) X]_, X2 and X3 are independently H, fluorine, chlorine, bromine, SO3H

COOH or NO2, with the condition that not more than two of X^, X2

and X3 is SO3H or COOH, and

d) M is as stated above.

The compounds of formula Ib are such with reference to

the structural formula I in which:

a) Y and Y° are independently H, fluorine or chlorine,

b) X and X° are independently H, fluorine, chlorine, bromine or NO2,

c) X]_, X2 and X3 are independently H, fluorine, chlorine, bromine, SO3H,

COOH and NO2, with the conditions that i) at least one but not more than

two of Xi, X2 and X3 are SO3H or COOH, and ii) at least two of X, X°, X1( X2 and X3 are fluorine, chlorine, bromine or NO2, and

d) M has the above meaning.

The preferred compounds of formula Ia have one or more of

the following features: a) both Y and Y° on each five-membered ring are fluorine or chlorine, b) at least two of X, X°, X^, X2 and X3 are fluorine or chlorine, more particularly that X and X° are fluorine or chlorine , and c) M is Fe, Cr, Mn or Ru. More preferred compounds of formula Ia have one or more of the following features: a) both Y and Y° on each five-membered ring are chlorine, b) at least two of X, X°, X^, X2 and X3 are chlorine, more particularly that X and X° is chlorine, and c) M is Fe.

The preferred compounds of formula Ib have one or more of the following features: a) Y and Y° on each five-membered ring are independently H or chlorine, b) one of X^, X2 and X3 is SO3H, c) at least two of X, X°, X]_, X2 and X3 are fluorine or chlorine, more particularly that X and X° are fluorine or chlorine, and d) M is Fe, Cr, Mn or Ru. More preferred compounds of formula Ib have one or more of the following features: 1) Y and Y° on each five-membered ring are independently H or chlorine, b) one of X1( X2 and X3 is SO3H, c) at least two of X, X° , X1( X2 and X3 are chlorine, more particularly that X and X° are chlorine, and d) M is Fe. Another preferred subclass of compounds of formula Ib are those in which one of Y and Y° on each five-membered ring has a meaning other than H, more particularly those in which both Y and Y° are fluorine or chlorine.

With respect to each ring R as described above, each ring R will contain the minimum substitution indicated above, but the positioning and the number of substitutions above this minimum on each ring R may vary. Preferably, each ring R is the same.

In general, it is preferred that only one of X 1 , X 2 and X 3 is a water-solubilizing group. It is also more particularly preferred that when one of Y and Y° has a different meaning than H, that both have a different meaning than H.

A subclass of compounds of formula Ib described in the application with serial no. 039,566 of April 17, 1987, wherein Y and Y° are H, X and X° are each chlorine, X^ and X2 are H and R3 is an electronegative group including a water-solubilizing group, including those in which any water-solubilizing group is in free acid form and compounds with and without ligands such as e.g. the chloride ligand form.

Compounds according to the invention with SO3H or COOH groups are water-soluble and the invention also includes such water-soluble compounds in which these groups are in water-soluble salt form with a cation of a base such as e.g. an alkali metal (sodium, potassium or lithium), an alkaline earth metal or an ammonium cation, preferably an alkali metal or ammonium cation. Such salt forms can be prepared by reacting a compound of formula I with a base using conventional methods.

M can be any transition metal capable of undergoing oxidation. Examples of preferred metals include Fe, Cr, Mn, Ru and Co. Particularly preferred metals are Fe, Ru and Mn. Furthermore, the metal may be united to a ligand. The axial ligands, usually one or two, but

occasionally more, may actually be any group capable of forming a single hydrolysable bond with M, as known in the art. Examples of axial ligands include, by way of illustration only -OCH 3 , -OH, amines, halide ions, especially chloride, and water.

In order to build up some of the catalysts in accordance with the invention, it can be difficult to use a starting material porphyrin compound which instead of its M group contains a metal (M°) such as e.g. Ni or Zn. While these particular compounds need not be particularly capable of sustaining oxidation, Ni or Zn (and Fe) activates the porphyrin ring and allows it to be substituted with the desired fluorine or chlorine group. When p-substitution is carried out and both X and X° are H, it is particularly desirable to use compounds in which M is Ni. The compounds of formula I in which M is replaced by Zn or Ni are useful starting materials, especially the Ni starting materials. By the expression "capable of undergoing oxidation" is meant a metal which is capable of being oxidized in the presence of an oxidizing agent and which can then be reduced while participating in the desired oxidation reaction, so that it can be oxidized again with the help of the oxidizing agent. In this sense, the porphyrins are referred to as catalysts, as typically small amounts can be used and mainly retained in the reaction systems.

When M unites to e.g. a halogen ligand (F, Cl, Br or I), the compound of formula I can be considered as a salt form, e.g. in the ratio M<+>and HAL<->in which HAL is the halogen. Such salts occur when M is in the valence state plus three, e.g. Fe<+++>, or in higher valence states, as known in the field.

As used in the description and claims, the following definitions will be used: Free base porphyrin - a porphyrin ring that does not contain a metal group.

Electronegative group - a chemical group that is electronegative and can attract electrons either inductively or via conjugation, also referred to as "electron-withdrawing" groups. Examples of such groups include, but are not limited to halogens (eg, Cl-, Br-, F-), H03S-, and O2N-.

Particular embodiments of the invention include the following variants:

Also within the scope of the invention are the non-metallic starting material compounds with the following formula:

wherein each Y and Y° is independently H, fluorine or chlorine, and each ring R is

wherein X and X° are independently H or a non-water-soluble-forming electronegative group, e.g. fluorine, chlorine, bromine or NO2, X1( X2 and X3 are independently H, or an electronegative group, including water-solubilizing electronegative

groups, including without limitation fluorine, chlorine, bromine, SO3H, COOH, or NO2, with the proviso that 1) when any of X^, X2, and X3 is not a water-solubilizing group, at least Y and Y° on each five-membered ring have another meaning than H, 2) when Y and Y° are both H, at least one but not more than two of X]_, X2 and X3 is a water-solubilizing group, e.g. SO3H or COOH, and at least two of X and X° and X^, X2 and X3 which is not a water-solubilizing group is independently an electronegative group which is not a water-solubilizing group, e.g. fluorine, chlorine, bromine or NO 2 , and 3) no more than two of X 1 , X 2 and X 3 are water-soluble, or water-soluble salts thereof in which the said water-solubilizing groups are in a corresponding water-soluble salt form.

Also included within the scope of the invention is a method for producing the above compounds. It has been found that the substituted porphyrin rings (hereinafter referred to as p-substitution) can be prepared in two ways. The first way is to start with unsubstituted porphyrin containing no metal (hereinafter referred to as free base porphyrin) and introduce metal into it. This can be accomplished by dissolving the free base porphyrin in a solvent such as DMF or CH3COOH. The metal is then added. This can be in the form of metal salts with any desired valence, e.g. M(II), or M(III) or a covalent form such as e.g. M(0) where M is the metal. While virtually any metal may be used, preferred metals include Ni, Fe and Zn, and particularly preferred metal salts include Fe(CO) 5 , FeCl 2 and FeCl 3 .

After the metal is introduced into the free base porphyrin, the next step is (3-substitution of the porphyrin ring. This step can be accomplished by contacting the porphyrin ring with an electrophilic reagent. Examples include electrophilic chlorinating and fluorinating agents such as molecular chlorine, molecular fluorine , and chlorosuccinamide (for halogenations) or high-valence metal halides C0X3, CeX4, or MnX3 (X is a halogen such as chlorine) or electrophiles donating -NO2- or -SC^H groups (for non-halogenation substitutions).

Then, if desired, phenyl groups can be substituted using standard methods.

When a metal such as If Ni or Zn is used, this is replaced by a metal capable of sustaining oxidation.

Alternatively, the steps of metal introduction, p-substitution and substitution on the phenyl rings may be carried out in any order deemed most advantageous. The invention thus includes further reaction schemes which include the following:

It has been found that the compounds of formula I are very stable and powerful catalysts in the presence of a wide variety of oxidizing agents. In addition, the compounds of formula Ib are water soluble. As also the water-soluble groups, e.g. sulphonate groups are electron-attracting, the stability of the catalyst is increased as it is now more difficult to destroy it by oxidation. Furthermore, this electron deficiency is transferred to the metal atom so that the catalyst becomes even more powerful as well as robust. The porphyrin catalysts are functional at virtually any pH, and at high temperatures (150°C or more), so that they can be used in many commercial processes.

The compounds of formula I can be used as oxidation catalysts in a wide range of processes where prior art has indicated possibly substituted phenylporphyrins as useful, the compounds of formula I being water soluble being particularly useful in processes where water solubility is desired or required. Such processes include, by way of illustration only, oxidation of alkanes (including cycloalkanes), oxidation of alkenes (including cycloalkenes), the oxidative conversion of lignin model compounds which are converted by the lignin-modifying and lignin-degrading fungal enzymes also known as ligninases, the use in modification or degradation of lignin , the use in the treatment of wood of different forms such as e.g. wood chips or wood pulp to aid or effect pulping or bleaching. Particularly pulp production-related processes of interest for the use of the water-soluble compounds Ib to assist with or carry out a modification or degradation of lignin are the well-known mechanical pulps such as e.g. thermomechanical masses, and when treating power masses, e.g. to effect bleaching. The compounds of formula I which are water insoluble can also be used in solvent mass production such as e.g. the known organosolv pulp production process. Other applications include the decomposition of organic pollutants in wastewater streams such as the chlorinated organic compounds in El-awann from the kraft pulp chlorine bleaching process. Of particular interest is the use of compounds of formula I as catalysts in the catalytic oxidation of alkanes (including cycloalkanes) for their hydroxylation (or keto formation in the end) and in the catalytic oxidation of alkenes (including cycloalkenes) to form epoxides (epoxidation). Such hydroxylations and epoxidations are known reactions which are usually carried out in an inert organic solvent, but aqueous systems can also be used. Accordingly, both the water-soluble and water-insoluble compounds of formula I are useful in such processes. In general, in addition to the stated advantages of the porphyrin according to the invention, the porphyrins can be used over a wide range of reaction temperatures including high temperatures up to 150°C or even higher, or over a wide range of pH values which can extend from about 1 to 14, more suitably from pH to pH 12.

The following examples illustrate the invention without limiting it.

EXAMPLE 1.

Synthesis of tetra(2,6-dichlorophenyl)porphinatoiron (III) chloride (TPPFeCl8).

A compound in which:

M = Fe, axially ligated to Cl,

X = Cl,

X° = Cl,

X1( X2, X3= H,

Y, Y° = H

Step 1, Preparation of H2TPPC18.

Pyrrole (redistilled: 6.94 mL, 100 mM), 2,6-dichlorobenzaldehyde (17.5 g, 100 mM), anhydrous zinc acetate (6.6 g, 36 mM), and 2,6-lutidine (150 mL, note 1) is placed in a 500 ml round bottom flask equipped with a Soxhlet extractor fitted with a reflux condenser. Anhydrous Na2SC>4 is placed in a thimble in the extractor and the reaction mixture is heated under reflux for five hours (note 2). After evaporation of the lutidine in vacuo, the resulting tarry residue is treated with toluene (500 ml) and allowed to stand in a refrigerator overnight. The fine purple crystals of ZnTPPClg are filtered and washed thoroughly with toluene (Note 3).

The zinc complex is dissolved in CH 2 Cl 2 (250 ml) and treated with trifluoroacetic acid (25 ml). This mixture is stirred for six hours (note 4) and poured into water (300 ml). The organic layer is separated, washed with saturated aqueous NaHCO 3 (150 mL) and water (2 x 150 mL), then concentrated after addition of methanol. The free base, H2TPPClg (Note 5) is collected by filtration, washed with methanol and dried. Yield 1.26 g.

Step 2, removal of chlorine contaminants.

The crude free base from step 1 is dissolved in CHCl3 (500 ml) and heated to reflux. A solution of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ, 600 mg) in dry benzene (40 ml) is added and heating is continued until the absorption at X = 658 disappears (Note 6).

The reaction mixture is evaporated to dryness, redissolved in hot CHCl3 (approx. 200 ml) and passed through neutral alumina (100 g, act. I). Oxidizing agent (DDQ) and other contaminants adsorb strongly initially, while porphyrin is eluted cleanly with CHCl3. The porphyrin is crystallized from the CHCl3 solution by concentration and addition of n-hexane.

Step 3, introduction of iron.

The free base (700 mg) is dissolved in degassed N,N-dimethylformamide (DMF, 400 ml) in a 1 liter three-neck round-bottomed flask equipped with a gas supply tube and a reflux condenser, the third neck being stoppered. The solution is heated to reflux (with N 2 or Ar bubbling) and treated with a solution of FeCl 2 4 H 2 O (3 g) in degassed DMF (100 ml). Heating is continued and the introduction of iron is monitored using UV-visible spectroscopy. In the Soret region the simple sharp absorption at = 418 changed to a split Soret at ^max = 360/418, while in the visible region the spectrum changed from<X>max = 512'588 ti]L Xmax= 508'580' 644 (note 7) • The heating is interrupted and air is bubbled through the solution above

2+

overnight to ensure that the inserted Fe is oxidized to the more stable Fe^<+-> compound.

The supernatant DMF solution is decanted from the solid FeCl3, concentrated in vacuo to approximately 200 ml and treated with dilute HCl (600 ml, 1:1). The hemine precipitates as a brown solid from a clear yellow solution. The solid is collected by filtration, washed thoroughly with water and dried in a vacuum desiccator.

The crude solid is re-dissolved in a minimum of CH 2 Cl 2 and passed through silica gel (act. I) contained in a sintered glass funnel (150 M) using CH 2 Cl 2 as elution solvent. The unreacted porphyrin is eluted cleanly and recovered by crystallization (approx. 75 mg). The hemin is then eluted using 5% CH 3 OH in CH 2 Cl 2 . This is evaporated to dryness, redissolved in CH2CI2 and extracted once with concentrated HC1 (equal volume, note 8). The organic layer is washed with water (until the water extract is neutral), dried (Na2SO4) and the hemin is isolated as shiny purple crystals using n-hexane. A first yield of 550 mg and a second yield of 60 mg are obtained.

Note 1. Lutidine is boiled under reflux with CaH2i for two hours and fractionally distilled under N2 at atmospheric pressure. The fraction that distills above at 143.5 - 144.5°C

are collected and stored under N2.

Note 2. Water produced by the reaction is distilled over together with the solvent, but is retained by the desiccant (Na2SC<4) in the Soxhlet apparatus while

the solvent is recycled.

Note 3. UV-visible spectrum (in CH2Cl2) of ZnTPPClg:

X = 420 (Soret), 510 (weak), 550, 585 (weak) nm. Note 4. UV-visible spectrum (in CH2CI2) of the decation

[H4TPPC18]<2+>: X = 430 (Soret), 576, 628 nm.

Note 5. UV-visible spectrum (in CH2CI2) of the free base H2TPPC18: X = 418 (Soret), 512, 588 nm. An absorption at X = 658 indicates the presence of some chlorine-containing contamination that should be removed. An absorption at X = 550 suggests incomplete metal removal.

Note 6. The relative intensity of X 656: 588 in the crude

porphyrin should be as high as 1 and the complete removal of the absorption at X = 656 requires about three hours. If the oxidation is not complete within three hours, a further 100 mg of DDQ should be added.

Note 7. In general, metal insertion is complete within three hours. Application of an inert atmosphere during

the reaction helps to prevent oxidation of

Fe to Fe before the introduction.

Note 8. Elution of the hemin with 5% CH3OH/CH2CI2 results in the partial exchange of the axial Cl ligand. Extraction with concentrated HC1 regenerates chlorinated iron (III) species.

EXAMPLE 2.

Sulfonation of ^TPPClg.

H 2 TPPClg (300 mg) is suspended in fuming sulfuric acid (14 ml) in a 25 ml three-necked flask equipped with a reflux condenser carrying a CaSO 4 ~ drying tube on top. The suspension is heated at reflux (oil bath temperature set at 165°C for seven hours during which the solid dissolves to give a clear green solution. Sulfur trioxide which sublimes and settles in the condenser must be carefully returned to the reaction flask at regular intervals. The solution is allowed to cool overnight.

The above solution is carefully added dropwise over a period of 30 minutes to 50 ml of ice-cooled water. The viscous solution is filtered into a 300 ml round bottom flask and treated dropwise (with stirring and cooling) with water (75 ml) followed by a suspension of NaHCO 3 (65 g) in water (100 ml) until it becomes slightly basic (pH 8) . Towards the end, the Na2SO4 crystallizes out and makes it difficult to stir (a 1 liter flask was needed). The solution had changed color from green (normal color in acidic medium) to red. Ethanol (approximately the same volume) is added to precipitate Na2S04, which is removed by filtration. Complete removal of Na2SO4 cannot be achieved even by chromatography (on silica gel or sephadex), dialysis and repeated recrystallizations. The compound exhibits a characteristic UV-visible spectrum of a meso tetrasubstituted porphyrin (absorption maxima in methanol: 423 nm (Soret), 521, 555, 602 and 657). Partial purification is achieved by dialysis and the sample is dissolved in a minimum amount of water (7 ml), diluted with methanol (100 ml) and crystallized by adding acetone (approx. 300 ml). A first portion of the dividend on

212 mg is obtained and a further yield of 105 ml is obtained from

mother liquor.

EXAMPLE 3.

Synthesis of the hemin from sulfonated H2TPPCI3.

A compound of formula Ib wherein:

M = Fe,

X, X° = Cl,

Xx=SO3H,

X2, X3= H,

Y, Y° = H.

The sulfonated I^TPPClg (105 mg) is dissolved in N,N-dimethylformamide (40 ml) in a 200 ml three-neck round-bottomed flask equipped with a reflux condenser. The solution is degassed by passing a slow stream of argon using a needle passed through a rubber membrane and heated to reflux. At the beginning of reflux, the mixture is treated with a solution of FeCl 2 4 H 2 O (500 mg) in degassed N,N-dimethylformamide (10 ml). Heating is continued (with argon bubbling through) and the introduction of iron is monitored spectroscopically. Metal insertion is complete within three hours. (Uv-visible in DMF, Soret at 424, 436 sh - double, alpha/beta at 575 and 613 sh, uv-visible of freebase porphyrin in DMF: Soret at 425, 520, 553, 660 and 655 nm). Air is bubbled through the cooled solution overnight to ensure complete oxidation of iron. Acetone (100 ml) is added dropwise with stirring and the metalloporphyrin precipitates as a brown solid. This is recrystallized from methanol and acetone to give 120 mg.

EXAMPLE 4.

Synthesis of chloro(mesotetraphenyl-p-octachloroporphinato)iron(III) Fe(TPP.<p>Cl8)Cl.

A compound of formula Ia wherein:

M = Fe, axially ligated to Cl,

X, X°, X1( X2,X3=H,

Y, Y° = Cl.

Step 1, synthesis of mesotetraphenyl-p-octachloroporphinato-nickel(II) (NiTPP.Cl8).

Mesotetraphenylporphinatonickel(II) prepared by conventional methods, (NiTPP, 670 mg, 1 nM) is read up in o-dichlorobenzene (75 mL). N-chlorosuccinimide (1.6 g, 12 nM) is added and the solution is heated in an oil bath at 140°C. The reaction, monitored by UV-visible spectroscopy (NiTPP exhibits a Soret absorption at 414 nm while in the product this is shifted to 440 nm), is complete in about 90 minutes.

The solvent is removed under vacuum and the residue is chromatographed on neutral alumina (activity I, 300 g), using chloroform as solvent. The product is eluted cleanly as a reddish-yellow solution and is crystallized by concentration and addition of methanol. NiTPP. (JClg is collected by filtration and washed with methanol and dried. Yield 736 mg (78%).

Analysis theoretical for C44<H2>0N4Cl8Ni: C 55.81, H 2.13, N 5.92, Cl 29.95.

Found: C 55.48, H 2.09, N 5.76, Cl 30.10.

<13>C NMR (75.4 MHz, CDCl3 at 76.997) 118.995, 127.563, 129.291, 133.783, 134.399, 135.510, 140.251.

MS (m/e) nominal mass of the most extensive peak in the isotope cluster, 946 (M<+>).

UV<Xm>ax (CH2C12) 440 (Soret), 554 nm.

Step 2, demetallization of NiTPP. (3Clg.

A stirred solution of NiTPP. (3Clg (210 mg) (from step 1, above) in dichloromethane (70 mL) is treated with concentrated sulfuric acid (50 mL) at room temperature. Over five minutes, a shiny green solid separates from a greenish-brown emulsion. After another 15 minutes of stirring the mixture is poured into ice (about 500 g) and more dichloromethane (total about 300 ml) is used to dissolve the solids. The organic layer (two-colored, yellow-green) is removed and the aqueous layer is extracted once with dichloromethane (100 ml) - trifluoroacetic acid (3 mL) and discard.The combined organic phase is washed with water

(2 x 250 ml), saturated aqueous sodium bicarbonate (200 ml) and dried (Na2SO4), after which mesotetraphenyl-fJ-octachloroporphyrin

(H2TPP. (3Clg) is isolated by concentration and addition of methanol. Yield 176 mg (90%).

<13>C NMR (75.4 MHz, 10% w/w CF3CO2H-CDCl3, CDCl3 at 77.141) 5, 121.922, 129.129, 129.770, 132.681, 134.236, 137.403, 141.856.

MS (m/e) nominal mass of the most extensive peak in the isotope cluster, 890 (M<+>).

UV Xmax(CH2C12) 452 (Soret), 552, 602, 720 nm,

Xmax (CF3C02H_CH2C12) 482 (Soret), 736 nm.

Step 3, introduction of iron.

Mesotetraphenyl-p-octachloroporphyrin (H2TPP . fJClg , 125 mg) from step 2 above, is dissolved in degassed N,N-dimethylformamide (DMF, 100 ml) in a 250 ml two-necked round-bottom flask equipped with a gas inlet and a reflux condenser. The solution is heated to reflux (with N2 bubbling through) and treated with a solution of FeCl2.4H20 (500 mg) in degassed DMF (20 ml). Heating is continued and incorporation of iron, monitored by UV-visible spectroscopy (H 2 TPP.pClg exhibits a Soret absorption at 452 nm, which shifts to 446 nm in the product), is complete within an hour. Heating is discontinued and air is bubbled through the solution overnight.

The supernatant DMF solution is decanted from the solid FeCl 3 , concentrated in vacuo (ca. 60 mL) and treated with dilute HCl (1:1, 120 mL). The hemine precipitates as a brown solid and is collected by filtration, washed thoroughly with water and dried in a vacuum desiccator.

The crude solid is dissolved in a minimum of CH2C12 and chromatographed on silica gel (20 g, activity I, 230 - 400 mesh). Initial elution with CH 2 Cl 2 removes the non-metallated starting material and the hemin is eluted with 5% CH 3 OH-CH 2 Cl 2 . The mixture is evaporated to dryness and the residue is taken up in CH 2 Cl 2 (100 ml) and extracted once with concentrated HCl. The organic layer is washed with water (4 x 100 ml), dried (Na 2 SO 4 ) and concentrated. Chloro(mesotetraphenyl-(3-octachloroporphinato)iron(III) is crystallized from n-hexane and isolated (two portions) with a total

yield of 85%.

Analysis theoretical for C44H20N4Cl9Fe: C 53.95, H 2.06, N 5.72, Cl 32.57,

Found: C 54.35, H 2.23, N 5.55, Cl 32.35.

MS (m/e) nominal mass of the most extensive peak in the isotope cluster, 979 (M<+>), 944 (M<+->Cl).

UV Xmax(CH2C12) 404/448 (Soret), 526, 564, 768 nm.

EXAMPLE 5.

Synthesis of chloro[mesotetra(2,6-dichlorophenyl)-p-octachloroporphinato]iron(III).

A compound of formula Ia wherein:

M = Fe, axially ligated to Cl,

X°, X = Cl,

X^, X2, X3= H.

Y, Y° = Cl.

Chloro.[mesotetra(2,6-dichlorophenyl)porphinato]iron(III) (from Taylor et al., 1984 J. Chem. Sei. Chem. Commun. 279-280) (FeTPPClgCl, 107 mg), and ferrous ferric chloride ( 600 mg) is suspended in o-dichlorobenzene (15 ml) in a 50 ml three-neck round flask equipped with a gas inlet tube and a reflux condenser attached to a drying tube, the third neck being stoppered. The reaction mixture is heated in an oil bath with stirring to 140°C and chlorine gas is bubbled through the mixture for five minutes. Stirring is continued and the course of the reaction is followed by means of invisible spectroscopy. [The starting material (FeTPPClgCl) exhibits a double Soret 370/420 nm which shifts to 396/444 nm in the product (FeTPPClgPClgCl) upon completion of the reaction.] The reaction mixture is cooled and the solvent is removed under vacuum. The residue is dissolved in dichloromethane (125 ml), washed with water (2 x 75 ml) and chromatographed on silica gel (40 g, activity I, 230-400 mesh). Dichloromethane is initially used to remove the p-chlorinated demetallated porphyrin and the hemin is then eluted using 5% CH 3 OH/CH 2 Cl 2 . The solvent is removed under vacuum, the residue redissolved in dichloromethane (200 ml) and extracted once with concentrated HCl (100 ml). The organic layer is washed with water (2 x 100 ml) and dried (Na2SO4)

and the product is crystallized from dichloromethane/n-hexane.

Yield 121 mg (88%).

Analysis theoretical for C44<H>12<N>4Cl17Fe: C 42.11, H 0.96, N 4.46, Cl 48.02.

Found: C 41.90, H 1.10, N 4.25, Cl 48.30.

MS (m/e) nominal mass of the most extensive peak in the isotope cluster, 1254 (M<+>), 1220 (M<+->C1).

UV<Xm>ax (CH2C12) 396/444 (Soret) nm.

EXAMPLE 6.

Synthesis of chloro[mesotetra(pentachlorophenyl)-p-octachloroporphinato]iron(III)

FeTPPCl20PCl8.Cl

A compound of formula Ia wherein:

M = Fe, axially ligated to Cl,

X, X°, X^, X2, X3= Cl,

Y, Y° = Cl.

Chloro[mesotetra(pentachlorophenyl)porphinato]iron(III) (from Taylor et al., supra) (FeTPPCl2Q.Cl, 90 mg) is dissolved in o-dichlorobenzene (15 mL) in a 50 mL three-neck round-bottomed flask equipped with a gas inlet and a reflux condenser attached a drying tube, the third neck being corked. Anhydrous ferric chloride (500 mg) is added and the solution is heated rapidly to 140°C in a preheated oil bath. Chlorine gas is bubbled for five minutes through the stirred solution and the temperature is maintained for one hour. The strong Soret absorption of the starting material (FeTPPCl 2 OCl) at 420 nm shifts to 442 nm as chlorination proceeds to completion.

The solvent is removed in vacuo and the residue is dissolved in dichloromethane (600 ml, note 1) and washed with water (2 x 200 ml) to remove excess ferric chloride. The organic phase is dried, evaporated to dryness, and the residue is dissolved in hot chloroform (50 ml, note 2) and passed through silica gel (60 g, activity I, 230-400 mesh) placed in a sintered glass filter funnel (150 M). Initial washing with dichloromethane removes the p-chlorinated demetallated porphyrin and the hemin is then eluted with 5% CH 3 OH-CH 2 Cl 2 and collected. The solvent is evaporated under reduced pressure, the residue is dissolved in dichloromethane (600 ml) and extracted once with concentrated HCl (200 ml). The organic phase is washed with water (3 x 250 ml), dried (Na2SC>4) and the perchlorohemine (FeTPPCl2g.pcigCl) is crystallized from chloroform (note 3) n-hexane). Yield (three servings), 77 mg (72%).

MS (m/e) nominal mass of the most extensive peak in the isotope cluster, 1668 (M<+>), 1663 (M<+->Cl).

UV<Xm>ax(CHCI3) 396/444 (Soret) nm.

Note 1. Due to the lower solubility of FeTPPCl20PCl8Cl (cf. FeTPPCl8(iCl8Cl) in dichloromethane, a larger volume of solvent is required to keep it

in resolution.

Note 2. The solubility of FeTPPCl20(JCl8Cl in chloroform is significantly higher than in dichloromethane and is therefore a

useful replacement in chromatography.

Note 3. Pure chloroform of spectroscopy is used

stabilized using non-polar hydrocarbon.

EXAMPLE 7.

Synthesis of chloro[mesotetra(4-sulfonatephenyl)-octachloroporphinato]iron(III) .

A compound of formula Ia wherein:

M = Fe, axially ligated with Cl,

X,X°,Xx,X3= H,

X2=SO3H,

Y, Y° = Cl.

Step 1, synthesis of mesotetra (4-sulfonatephenyl)-(J-octachloroporphyrin).

Mesotetraphenyl-|3-octachloroporphinatonic nickel (II) (NiTPP.Cl8,

40 mg) (from example 4) is suspended in concentrated sulfuric acid

(10 ml) and immersed in an oil bath preheated to 120°C. During five minutes of heating, the starting material is demetallized and dissolved, producing a dark green solution. The heating is continued for five hours and the solution is stirred

room temperature for twelve hours. The reaction mixture is poured into crushed ice (50 g), neutralized (while cooling) with a saturated sodium hydroxide solution, filtered and evaporated under reduced pressure.

The residue is extracted with methanol, the methanol solution is evaporated and the crude product (dissolved in a minimum amount of water) is passed over a cation exchange column (Dov/ex 50 WX-8, H+ form). The porphyrin fraction is collected, neutralized with sodium hydroxide, evaporated to dryness, and the residue is further purified in methanol by chromatography on a Sephadex LH 20 column. The porphyrin is crystallized from acetone.

UV X max, s (CHoJOH) 464 (Soret), 634, 746 nm.

X , (CH-sOH-NaOH) 480 (Soret), 718 nm.

max J

Xmax(CH3~H<+>) 486 (Soret), 722 nm.

Stage 2, introduction of iron.

Mesotetra(4-sulfonatephenyl)-p-octachloroporphyrin (30 mg) and sodium acetate (20 mg) were suspended in glacial acetic acid (40 mL) and heated at 100°C under nitrogen. A solution of FeCl 2 .4H 2 O (70 mg) in water (1 ml) was added and the incorporation of iron was followed by UV-visible spectroscopy. The reaction was complete after about an hour. The reaction mixture was cooled to room temperature under nitrogen and was stirred overnight, exposed to air.

The brown solid was filtered off, washed thoroughly with acetone and dried to give the above product.

UV X max, s (water, pH = 6) 402 (sh), 420 (Soret), 564, 758 nm.

EXAMPLE 8.

Synthesis of chloro [mesotetra (2, 6-dichloro-3-sulfonatphenyl)-|3-octachloroporphinato]iron(III).

A compound of formula Ia wherein:

M = Fe, axially ligated to Cl,

X, X° = Cl, x3 = SO3H,

XlfX2= H,

Y, Y° = Cl.

Step 1, sulfonation.

Chloro[mesotetra(2,6-dichlorophenyl)-(3-octachloroporphinato]iron(III)

(30 mg) was placed in a 50 ml three-neck round-bottomed flask fitted with a reflux condenser fitted with a drying tube (CaSO^) and treated with fuming sulfuric acid (10 ml). The starting material was demetallized and dissolved immediately. The resulting green solution was heated at 165°C in an oil bath for seven hours. Condensation of sulfur trioxide inside the condenser was reduced to a minimum by adjusting the cooling water as needed. The reaction mixture was stirred at room temperature overnight and carefully poured onto ice (200 g).

The aqueous solution (UV: 468 (Soret), 602, 640, 702 nm) was neutralized with a saturated solution of NaOH, ethanol (200 ml) added and cooled. Crystallized sodium sulfate was filtered off, the filtrate was concentrated (10 ml), diluted with ethanol and filtered again. The filtrate was evaporated to dryness, dissolved in a minimum amount of water and passed through Dowex 50 W-X8 ion exchange resin (H+<->form). The eluate was neutralized with dilute sodium hydroxide, evaporated to dryness, redissolved in methanol and the product crystallized from acetone. Yield 36 mg (two servings).

UV Xmax(DMF) 474 (Soret), 584 (sh) 626, 680 nm.

Stage 2, introduction of iron.

The porphyrin prepared as described above (15 mg) was dissolved in N,N-dimethylformamide (10 ml) in a 50 ml three-necked round bottom flask and degassed by passing nitrogen for one hour. The solution was heated at reflux and treated with 1 mL of a basic solution of FeCl 2 -4H 2 O (220 mg) in N,N-dimethylformamide (DMF, 5 mL). An immediate color change from green to yellowish brown was observed. Reflux was continued for 15 minutes and a UV spectrum [X , in DMF: max 452 (Soret), 582, 630] indicated that the metallization was complete. The reaction mixture was allowed to cool and was stirred overnight at room temperature (exposed to air). Acetone (50 mL) was added, the product collected by filtration and crystallized from methanol-acetone.

UV:<X>max (CH 3 OH) 448 (Soret), 572, 660 nm.

The product was further purified by ion exchange chromatography (aqueous solution, Dowex 50W-X8 H+<->form) followed by crystallization from acetone.

UV X , (water, pH = 6) 422 (Soret) nm.

max

X , (water, pH = 9) 402 (sh), 426 (Soret), 604, 656 (sh), ITLclKS

740 nm.

EXAMPLE 9.

Catalysis of the oxidation of lignin model compounds with FeTPPCl8S.

Three lignin model compounds, 1, 4-^dimethoxybenzene, a p-0-4 model (arylglycerol (3-aryl ether substructure of lignin) and a 1 model (arylglycerol-f3-aryl substructure of lignin (see Kersten et al. 1985 J. Biol. Chem. 260: 2609-2612, Tien et al. 1983 Science 221: 661-663, and Kirk et al. 1986 Biochem, J. 236: 279-287) is reacted with an iron (III) (tetraphenyloctachloro)-sulfonatoporphyrin (FeTPPClgS ).A final concentration of 50 µM FeTPPClgS is reacted with 5 mM final concentration of the oxidizing agent t-butyl peroxide. The results indicate that FeTPPClgS mimics the enzyme ligninase.

Using 1,4-dimethoxybenzene as a substrate, FeTPPClgS produced spectral changes, but unlike ligninase, the benzaquinone product is not formed.

|The 3-0-4 model with FeTPPClgS gives the same products as with ligninase, and additionally demethoxylates to a greater extent than ligninase. Products produced include veratrylaldehyde and additionally traces of veratric acid which have not been observed with the ligninases, and consequently further indicate the greater oxidizing potential of porphyrins compared to the ligninases.

The p-l model with FeTPPClgS gives methanol as well as other products as with ligninase, including veratrylaldehyde and trace amounts of veratric acid.

EXAMPLE 10.

Treatment of lignin with the porphyrins in Examples 7 and 8.

250 µg of the Kraft softwood lignin Indulin AT (Westvaco Corporation, Charleston Heights, S.C.) is dissolved in 2 mL of DMF. Peracetic acid is used as oxidizing agent at a final concentration of 1.84 uM. In separate experiments, the porphyrins in previous examples 7 and 8 are used, with a final concentration of 500 µM. The reaction mixture is stirred at room temperature for 24 hours and the resulting products are analyzed by gel permeation chromatography using a TSK 4000 column with 1:1 chloroform:dioxane (Phenomenex, Rancho Palos Verdes, Ca.). Absorption is monitored at 280 nm and in each case a clear shift of the peak area to the right was observed, indicating a breakdown of the lignin.

EXAMPLE 11.

Treatment of veratryl alcohol with the porphyrin manganese-octachloro-tetrasulfonatoporphyrin.

Veratryl alcohol, a lignin-related compound, with a final concentration of 1 mM is reacted with 1 µM manganese-octachlorotetra-sulfonatoporphyrin (MnTPPClgS) in water at room temperature. Various oxidizing agents are present, including hydrogen peroxide, sodium hypochlorite, t-butyl peroxide, cumyl hydroperoxide, potassium iodate and iodosylbenzene, as in Table 1. The concentration of oxidizing agents is from 50-100 mM and the pH is from 1-10. The product is veratrylaldehyde. The yield depends on the oxidizing agent and pH.

EXAMPLE 12.

Treatment of veratryl alcohol with iron-octachlorotetraphenyi-sulfonatoporphyrin.

The same general procedure as stated in Example 11 is followed, with the exception that the catalyst is iron-octachlorotetraphenyl-sulfanatoporphyrin. The results are given in table 2.

EXAMPLE 13.

Catalytic efficiency of p-chlorinated mesotetraphenylhemines.

Catalytic activities of the hemins FeTPPClg.pcig.Cl and FeTPPC^Q•pcigCl are investigated by hydroxylation reactions (cyclohexane as substrate) and epoxidation reactions (cyclohexene as substrate) as described under: -4 -3 Iodosopentafluorobenzene (2.0 mg, 6.4 x 10 mol.dm ) is mixed with the substrate (1.0 mol.dm<3>) in dichloromethane in a culture tube with a silicone rubber membrane. The catalyst, in dichloromethane -4 -3

(1.0 x 10 mol.dm ) are introduced and the reaction mixture is mixed

continuously until either the solid disappears or the catalyst is destroyed. The yields of the products are determined by means of GLC (Carbowax 20M and SE 30), and the results are compared with the results of octachlorohemine (FeTPPClg.Cl) and are summarized in Table 5.

EXAMPLE 14.

Preparation of chloro[mesotetra-(4-carboxyphenyl)-p-octachloroporphinato]iron(III) - a compound of formula I in which Y and Y° are chlorine, X, X°, X]_ and X3 are H, X2 are carboxy and M is Fe(Cl).

A compound mentioned above is preferably prepared sequentially by 1) reaction of p-carboxybenzaldehyde methyl ester with pyrrole in a conventional manner to give the free base porphyrin, 2) Ni is introduced to form the Ni-containing porphyrin (M = Ni) on a conventional manner, 3) the Ni-containing porphyrin is chlorinated with chlorosuccinimide in a manner described herein to form the carboxy-substituted phenyl-p-octachlorinated porphyrin containing Ni, 4) Ni is removed in a manner described herein to form the corresponding free base porphyrin, 5 ) the methyl ester is removed in a conventional manner to form the free acid, and 6) Fe is introduced using FeCl 2 in a manner indicated herein for the analogous compound. By following this procedure, the above-mentioned porphyrin was prepared and proved to be catalytically effective.

The above-mentioned porphyrin can also be prepared by starting from the free base meso-4-carboxyphenylporphyrin, a known compound, methyl esterification of the carboxy groups and then proceeding as indicated in steps 2 to 7 above.

EXAMPLE 15.

Treatment of cellulose pulp.

Northern softwood pulp (consistency 2.5%) in an amount of 2 g was incubated in separate experiments with 2.5% (w/v) sodium hydroxide in the presence of 10 mM t-butyl peroxide in the absence of a porphyrin as a control, or in the presence of 10 mM of the porphyrin of Example 7.

The above experiments were repeated using 50 mM sodium citrate instead of sodium hydroxide.

The two sets of above experiments were repeated using 0.5% (w/v) sodium perchlorate in place of the t-butyl peroxide, except that the perchlorate/citrate combinations were omitted.

All of the above sets of experiments were then repeated using the porphyrin of Example 8 instead of the porphyrin of Example 7.

In each set of experiments, the Kappa number of the control samples and the porphyrin-treated pulp samples were measured and compared after all treated pulps had been extracted with alkali in a conventional manner. A generally greater reduction in the Kappa number was observed with the porphyrin-containing experiments and then with a greater reduction with the experiments using sodium perchlorate.

EXAMPLE 16.

Treatment of cellulose pulp with porphyrins:

A: mesotetra(2,6-dichloro-3-sulfonatephenyl)-p-octachloroporphinato

iron(III), and

B: mesotetra(4-sulfonatephenyl)-p-octachloroporphinato

iron(III).

A number of samples (2 g) of Northern softwood pulp were each washed with 500 ml deionized water, filtered and then placed in an 80 ml Na-citrate buffer (50 mM, pH 5) at 60°C. Tert-butyl hydroperoxide was added to 0.5% (w/v) followed by addition of the porphyrin. The samples were stirred in an oven at 60°C for 18 hours after which they were washed with approximately 1.5 L of buffer, added to 80 ml of 2.5% (w/v) sodium hydroxide (60°C) and stirred in an oven at 60°C for a further 90 minutes. The samples were then washed with 2.5 L of deionized water. Kappa measurements were made on all samples to determine the reduction in lignin content and the results are given below.

Claims (12)

1. A compound of formula (I) wherein M is a transition metal capable of undergoing oxidation, M optionally being axially ligated to a ligand, each Y and Y° is independently H, fluorine or chlorine, each ring R is wherein X and X° are independently H, fluorine, chlorine, bromine, or NO2, xl' x2 °9 x3 is independently H, fluorine, chlorine, bromine, SO^ H, COOH or N02 , with the conditions that 1) when none of X1 ( X2 and X3 is SO3 H or COOH, has at least one Y and Y° on each five-membered ring a meaning other than H, 2) when Y and Y° are both H, at least one but not more than two of Xlf X2 and X3 are SO3 H or COOH, and at least two of X and X°, and X1 ( X2 and X3 which are not SO3 H or COOH or N02 is independently fluorine, chlorine, bromine or NO2, and 3) no more than two of X^ , X2 and X3 are SO3 H or COOH, or a compound of formula I in which SO3 H and COOH groups are in water-soluble salt form. 2. A compound as stated in claim 1, characterized in that M is Fe. 3. A compound as stated in claim 1 or 2, characterized in that both Y and Y° on each five-membered ring are chlorine. 4. A compound as stated in claim 3, characterized in that at least two of X, X°, X^, X2 and X3 are chlorine. 5. A compound as stated in claim 4, characterized in that X and X° are chlorine, X^ is SO3 H, X2 and X3 are each H, or a salt thereof. 6. A compound as stated in claim 4, characterized in that X, X°, X]_, X2 and X3 are each chlorine. 7. A compound as stated in claim 4, characterized in that X and X° are chlorine, and X1 (X2 and X3 are each H. 8. Use of a compound as specified in one or more of claims 1-7 as an oxidation catalyst. 9. Procedure for modifying or breaking down lignin in wood, characterized in that the wood is treated with an effective amount of an oxidizing agent in the presence of a compound as stated in one or more of claims 1-7. 10. Procedure for treating waste water containing chlorinated organic pollutants, characterized in that the wastewater is treated with an effective amount of an oxidizing agent in the presence of a compound as stated in one or more of claims 1 - 7. 11. Method as specified in claim 10, characterized in that the waste water is an El waste water. 12. A compound of formula (II) wherein each Y and Y° is independently H, fluorine, chlorine, each ring R is wherein X and X° are independently H, fluorine, chlorine, bromine or NO2, Xj_, X2 and X3 are independently H, fluorine, chlorine, bromine, SO3 H, COOH or NO2 , with the conditions that 1) when none of X2 and X3 is <S> 03 H or COOH, at least one Y and Y° on each five-membered ring has a meaning other than H, 2) when Y and Y° are both H, at least one but not more than two of Xi- X2 and X3 are SO3 H or COOH, and at least two of X and X° and those X1 ( X2 and X3 that are not SO3 H or COOH or NO2 , is independently fluorine, chlorine, bromine or NO2 , and 3) not more than two of X] _, X2 and X 3 are SO3 H or COOH, or a compound of formula (II) in which SO3 H and COOH groups are in water-soluble salt form.