Metal compound removal

DESCRIPTION

REMOVAL OF METAL COMPOUNDS

The invention is directed to a process for removing metal compounds, such as a catalyst or catalyst debris, from liquid reaction systems. More particularly, the invention aims at the removal of metal compounds, such as a catalyst or catalyst debris, from homogeneously catalyzed reaction systems.

Metal compounds are used in a variety of applications, for example as catalysts, dyes or pharmaceutically active compounds.

Metal complex-based catalysts generally comprise at least one metal compound which at least consists of at least one metal atom and / or at least one ligand, or at least one metal ion and / or at least one counterion and / or at least one ligand. Such catalyst systems are very effective and selective catalysts in homogeneous catalyst systems for a wide range of reactions. However, it is often very difficult to remove the (homogeneous) catalyst, or its remains, from the reaction mixture after completion of the reaction. Processes of

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Extraction, recrystallizations, membrane filtration or distillation steps to remove the catalyst or its remains.

Other methods describe a modification of homogeneous catalysts that simplifies the separation of reaction products. However, such a modification of a homogeneous catalyst also alters its catalytic properties.

Catalysts and / or their remains must be removed from a process stream to obtain pure products. A simple and effective method for purifying process streams of catalysts and / or their remains is desirable, also from an economic and environmental point of view.

US 4,413,118 describes a process in which organic sulfur compounds containing a carbon-sulfur double bond are used to remove metals from the homogeneous catalyst group VIII of chemical process streams. US 4,855,400 describes the removal of carbon monoxide / olefin polymer catalyst residues with a palladium catalyst complexing agent. US 4,952,304 describes the removal of a group VIII catalyst and cocatalyst by treating the contaminated product with an aqueous solution of a silicate, borate or carbonate. Catalyst residues are extracted into the aqueous layer.

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- 3 Fedotov et al. describe the use of membranes to separate a bulky homogeneous catalyst from the reaction mixture in Catalysis Letters 1990, 6, 417-422.

US 6 303 829 and US 6 307 108 describe the use of fractional countercurrent extraction to remove metal-organophosphorus complexes from the reaction product fluid. Patent 4,429,057 describes the removal of volatile precious metal catalysts from a process stream by selective extraction into alcoholic liquids. US 4,950,629 describes the precipitation of homogeneous catalysts of a reaction solution solvent by reaction with lower alkanoic acid.

US 6 187 962 describes the separation of a homogeneous catalyst from a hydroformylation process stream by extraction methods.

US 4,35,810 describes the removal of an iron oxidation catalyst by reacting the iron catalyst with an iron oxidizing material that will cause precipitation of the iron catalyst.

UK Patent No. 1036775 describes the extraction of heavy non-ferrous metal from water solutions by sorption with heteropoly acid salts and subsequent removal of the sorbent from the solution.

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Many of the described processes lack efficiency and only partially remove catalyst residues. In addition, additives that are used contaminate product mixtures and are difficult to remove from the process stream. This makes the described methods unattractive from a process point of view.

It is an object of the present invention to provide a process that does not have all of the above disadvantages.

The invention is based on the idea that certain compounds, in particular heteropoly acids, have the property to bind very effectively and selectively to metal compounds, i.e. compounds comprising at least one metal atom or ion such as homogeneous metal catalysts. thus forming an insoluble precipitate. These heteropoly acids may also be attached to supports such as those based on various insoluble oxides and organic supports.

Accordingly, the present invention relates to a process for separating at least one metal compound and / or component thereof from a mixture, said process contacting said mixture with a heteropoly acid or heteropoly acid anion, the heteropoly acid being or heteropoly acid anion anchored to a solid support material, thereby producing a precipitate

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Comprising the heteropoly acid or heteropoly acid anion and the metal compound and / or its component. It may be found that the precipitate is insoluble in said mixture (under contact conditions).

Accordingly, it is possible to place a mixture - generally comprising at least the metal compound containing the metal compound (s) with a heteropoly acid or a heteropoly acid modified support material, such that the metal compound and / or a component thereof may be removed from the mixture by separating the resulting solids from the mixture. This invention provides a tool for effectively removing metal compounds, such as catalysts or catalyst debris, from a liquid, for example, a liquid process stream. The invention is particularly suitable for removing or recovering from a liquid solution a homogeneous metal compound or component thereof dissolved in a liquid solution; furthermore, the invention is particularly suitable for purifying a solution containing a homogeneous metal compound.

The term homogeneous metal compound is used herein to describe a metal compound dissolved in a solvent, a metal compound present in a colloidal phase (hereinafter referred to as a colloidal metal compound), a dispersed metal compound, a metal compound in an emulsion, a metal compound in a sun and in general to describe metallic compounds that are

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They are present in a fluid system such that it generally does not allow the metal and / or metal compound to be easily separated by filtration of the fluid.

Components of metal compounds which may be separated include unbound metal portions, ligands and counterions.

A mixture from which the metal compound and / or a component thereof is separated may be any fluid containing said metal compound and / or its component dissolved, suspended, dispersed or otherwise contained in said fluid.

A process according to the invention may be used to achieve partial or essentially complete removal of metal compounds and / or components thereof such as catalysts or catalyst debris. Of course, it is possible for various types of metal compounds and components to be removed simultaneously or subsequently in a process according to the invention.

Very good results have been achieved with a method according to the invention wherein a compound comprising an ionic metal moiety is removed. We note that the ionic metal moiety may be either anionic (e.g. Ru ') or cationic.

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The present invention is not limited to the removal of catalysts and / or their remains. A process according to the invention may also be used to remove or purify other metal compounds, for example complexes used as dyes or metal chelates for pharmaceutical purposes.

The invention may be used to recover metal compounds or to purify products such as pharmaceutical or food products that may be contaminated with metal compounds, such as catalysts or their remains, which have been leached from a (supported) catalyst into the product.

In one embodiment, the invention is directed to a process for removing at least one homogeneous metal compound (and / or a component thereof), preferably a dissolved metal compound or a colloidal metal compound, from a mixture - for example a reaction mixture - said process comprising contacting said mixture with a heteropoly acid anchored to an insoluble solid support, thereby producing a precipitate.

In one embodiment, the invention is directed to a process for purifying a mixture containing at least one homogeneous metal compound (and / or a component thereof), preferably a dissolved metal compound or a colloidal metal compound, comprising

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Said process contacting said mixture with a heteropoly acid, anchored to an insoluble solid support, thereby producing a precipitate and recovering the mixture.

In one embodiment, the invention is directed to a process for recovering at least one homogeneous metal compound (or a component thereof), preferably a dissolved metal compound or a colloidal metal compound, for example, a homogeneous metal catalyst from a said process comprising contacting said mixture with a heteropoly acid, anchored to an insoluble solid support, thereby producing a precipitate that is substantially insoluble in said mixture and recovering the metal compound one or more components thereof from said precipitate.

The invention is also carried out in a process for carrying out a chemical reaction, wherein a reaction mixture, upon completion of the reaction, is contacted with a heteropoly acid, optionally anchored to an insoluble solid support.

The present invention comprises an embodiment wherein a heteropoly acid or anion thereof is added to a mixture, thereby forming an insoluble precipitate with the metal compound (or with an atomic or ionic metal moiety) which may be separated from the mixture using techniques. conventional separation It is assumed that the heteropoly acid or anion thereof

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- 9 interacts with the metal species, thus forming a complex that is insoluble (under contact conditions). Where metal species are complexed with one or more ligands, these ligands will generally remain attached to the metal and will be removed together with said insoluble complex. This enables at least part of the ligands to be recovered as well, which may be important if the ligands are expensive and / or contaminate the product mixture.

The invention further comprises an embodiment wherein the heteropoly acid or anion thereof is to some extent attached to a solid support material. In this case the same principles apply but the additional advantages are that the risk of contamination of the mixture with heteropoly acids or anions is avoided or at least significantly reduced. In addition, it facilitates the separation of the metal compound from the process stream because liquid-solid separation can be easily performed and it is possible to separate the mixture and the heteropoly acid-bound metal compound in a fixed bed application.

This invention allows the bonding of homogeneous metal compounds or components thereof, preferably dissolved metal compounds or colloidal metal compounds - such as homogeneous metal catalyst, catalyst remains or metal-based color indicating means - from a mixture (reaction ).

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In this regard, the terms catalyst and catalyst remains are both used to indicate all components that may be present in a catalyzed reaction mixture. Such catalyst, or catalyst debris, at least typically consists of at least one metal atom and / or at least one ligand, or at least one metal ion and / or at least one counterion and / or at least one. one calling. More particularly, this includes all catalyst-related components that are present in the mixture (reaction), such as catalyst precursors, active catalyst and catalyst decomposition products, or catalyst or debris thereof, which have been leached from a catalyst (supported) into the reaction mixtures.

Removal may refer to the removal of at least part of the metal species, but also, if applicable, the removal of the ligand (s) and / or counterions. When using the term catalyst, it is to be understood that it encompasses all said components.

More particularly, the invention is useful for removing metal complexes such as catalyst materials consisting of at least one metal atom.

<td>and / or</td><td>fur</td><td>any less</td><td>one</td><td>calling, or</td><td>fur</td><td>any less</td><td>one</td><td>ion</td><td>of metal</td>

<td>and / or</td><td>fur</td><td>any less</td><td>one</td><td>calling, or</td><td>fur</td><td>any less</td><td>one</td><td>ion</td><td>of metal</td>

<td>and / or</td><td>fur</td><td>any less</td><td>one</td><td>counterion</td><td>and / or</td><td colspan="2">at least</td><td>one</td><td>calling.</td>

These complexes can be represented by the formula M_m(L)_noXp where M represents a metal atom or ion of

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Metal, preferably a transition metal atom or ion, more preferably Rh, Ru, Ir, Pd, Pt, Ni or an ion thereof, where each L represents an organic or inorganic molecule with electron donating properties, preferably a molecule containing one or more heteroatoms such as P, S, N or 0 or a molecule containing one or more unsaturated bonds, more preferably a molecule selected from the group consisting of phosphines, nitrogen and / or oxygen-containing ligands (e.g. acetonitrile, CO or H₂0), cyclic dienes (e.g. cyclooctadiene

<td>(cod)),</td><td>cyclic trienes;</td><td></td><td></td>

<td>where m</td><td>is at least 1;</td><td></td><td></td>

<td>where n</td><td>is an integral in the range 0-6;</td><td></td><td></td>

<td>Where</td><td>each X- represents a</td><td>portion</td><td>inorganic,</td>

preferably selected from the group consisting of H-, Cl-, BF₄-, C10₄_, SbF₆_ NO₃_, FEDERAL POLICE₆negatively charged anionic and complex organic molecules of a metal ion; Preferred examples of such negatively charged metal ion complexes include transition metal ionic complexes (e.g., Rh, Ru, Ir, Pd, Pt, an actinide, a lanthanide) and alkaline earth metal ion complexes;

where p is an integral chosen in the range 0-8.

Included are dissolved, and / or finely and stably dispersed aggregates of metal complexes of the formula M (L)_noX_P and multimetallic compounds (ie where m&gt; l). The compound may comprise more than one portion of

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- 12 metal, for example in the case of a colloidal metal compound.

Particularly good results were achieved with a process for removing compounds with a single metal portion per compound (ie, m = 1).

A couple of examples of metal complexes that can be removed in a process according to the invention are complexes that are obtained from precursor complexes [Rh ((R, R) -Me-DuPHOS) (COD)] BF₄ ((R, R) -Me-DuPHOS = (-) - 1,2-bis ((2R, 5R) -2,5-dimethyl phospholane) benzene), [Ru ((R) -BINAP) Cl₂] ₂-NEt₃ (R) -BINAP = (R) - (+) -2,2'-bis (different

<td>Nylphosphino) -1,1'-binaftil,</td><td>Pd (OAc)₂,</td><td>Rh (CO) (H) PPh₃)₃,</td>

<td>NiNO₃(H₂O)₆.</td><td></td><td></td>

<td>Also, compounds</td><td>metallic</td><td>originating in</td>

Dispersed heterogeneous materials which have been added to the reaction mixture for catalytic or other reasons may be removed by a process according to the present invention.

Heteropolyions are polymeric oxoanions (polyoxometalates) that can be formed by condensation of two or more oxoanion species. Heteropoly acids are protonated heteropolyions. The term heteropolicompound (HPA) is used for acid forms and salts. Unless otherwise indicated, the term heteropoly acid

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13 is used herein to describe both the acid form and the salt form. Heteropolyions are composed of oxides of addendum atoms (V, Nb, Mo, W, etc.) and heteroatoms (P, Si, etc.). Structures are classified into various groups based on similarity of composition and structure such as Keggin type, Dawson species, Waugh species, Anderson species, Silverton species and their lacunar and other crystalline or non-crystalline forms, and anions of the foregoing. Heteropolicomposites contain one or more strong protons which may be partially or completely substituted by alkaline, alkaline earth or quaternary ammonium ions. Other HPA-related compounds are organic and organometallic polyanion complexes. Keggin type heteropoly acids are preferred in this invention. Keggin heteropolicomposites are generally represented by the formula (XM₁₂O₄₀)^m_, where X is a heteroatom, such as P, Si, etc., and where M is an addendum atom, such as V, Nb, Mo, W, etc. Examples of particularly suitable heteropoly acids are phosphotungstic acid (PTA), phosphomolybdic acid (PMA) and silicotungstic acid (STA).

As indicated above, the heteropoly acid may be used neat or dissolved in a suitable solvent (solvents wherein the heteropoly acid dissolves, for example, polar solvents such as alcoholic solvents, H₂0) or attached to a support material. Of course, a mixture of several different heteropoly acids may be used according to the invention.

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Contact between the supported or unsupported heteropoly acid or anion generally occurs in a liquid at a temperature of from about -80 degrees C to about 250 degrees C for a period from about 1 minute to about 50 hours. Preferably, this occurs at temperatures of from about 20 degrees C to about 100 degrees C over a period of from about 0.1 to 12 hours.

The ratio of metal compound to heteropoly acid may vary over a wide range, depending on the purity requirement of the treated reaction mixture and the desired rate of the removal process. For many purposes, for example for complete removal of metal compounds, usually at least 1 equivalent of heteropoly acid is used; here, 1 equivalent is defined as 1 acidic point per metal ion or metal atom.

However, a lower amount of heteropoly acid may be used, for example, because complete removal is not desired. The amount of heteropoly acid will typically be at least 0.1 and usually up to 4000 equivalents of heteropoly acid. Preferably, 0.5-1000 equivalents of heteropoly acid are used if the aim is to remove at least most metal compounds. Very suitable is an embodiment where 0.75-100 equivalents of one or more heteropoly acids were used. Very good results were achieved with

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An embodiment in which 1-50 equivalents of heteropoly acid was used.

Typically, in a method according to the present invention, the supported heteropoly acid or anion thereof is present in a weight ratio with the support of from about 0.01: 1 to about 20: 1.

Suitable support materials are insoluble oxides, organic supports and combinations thereof. Preferred examples of insoluble oxides are alumina, silica, zirconia, titania, zinc oxide, magnesium oxide, active carbons, zeolite clay materials and combinations thereof. Preferred organic supports are polymers, oltomers, composites and materials coated with an organic portion. The supports may be structured materials, for example shaped materials such as a star-shaped material or a maze or applied to another support such as a structured packaging (monolith and the like).

Contact may be by any method that allows the heteropoly acid or anion to be in good contact with the mixture (reaction). Where unsupported materials are used, they may simply be mixed into the reaction mixture in an appropriate amount, followed by separation of the insoluble complex from the liquid. The supported material may be suitably contacted, such as using a chromatographic method, using

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16 a fixed bed under slurry reaction conditions or using structured compaction. After the mixture (reaction) and solid support have been in contact, the metal compound, for example the catalyst or its remains, may be removed from the mixture (reaction) by simple filtration, sedimentation, centrifugation or decantation techniques. 0 The metal compound may be recovered from the solid material, for example by washing with a solution containing suitable compounds or by removing the support by methods used in precious metal refining.

A method according to the invention is particularly suited for the removal of a metal catalyst or remains thereof from a reaction mixture, inter alia because reaction products usually have no chemical interaction with the supported heteropoly acids or anions or unsupported, with or without linked homogeneous catalysts, and may be separated, unaffected, from supported or unsupported heteropoly acids or anions, with or without homogeneous catalysts attached. This allows a homogeneous metal catalyzed reaction to be carried out and to recover / remove homogeneous catalyst remains by a simple method. In this way the catalyst can be easily recovered and / or a very pure reaction mixture can be obtained.

In case of use of the modified support with heteropoly acids or anions in a fixed bed application, the

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The reaction mixture containing the metal compound, such as the catalyst or its remains, may be passed through the bed. The metal compound will adhere to the solid material and the product will flow through the bed unaffected. If desired, the acidity of the fixed bed material can be modified by adding a base, for example Et₃N or

LiOH and other salts. If catalyst remains are colored, the saturation of the fixed bed may be visually monitored.

Other ways of connecting the remains of the homogeneous catalyst to the modified support are to slurry the product solution with modified support material. After some time, the modified support material - with gripped catalyst debris - can be removed from the process stream by simple decanting, filtration, centrifugation or sedimentation techniques. 0 Modified support material can be collected and valuable materials - for example precious metals - can be recovered and reused.

Modified support may be prepared by transforming the slurry support into a polar solvent or support, preferably into a solvent in which the heteropoly acid or anion is also soluble. To this suspension is added a heteropoly acid or anion solution in which the weight ratio of the heteropoly acid or its anion to the support is present from about 0.01: 1 to about 20: 1. In a method according to the invention the reaction

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Between the support and the heteropoly acid is carried out at a temperature of from -80 to 250 degrees C, preferably at a temperature from 0 to 100 degrees C. Reaction times may vary within wide limits. The reaction time may, for example, be suitably chosen from 2 to 16 hours. After completion of the reaction, the solid material may be washed with any solvent capable of removing unsupported heteropoly acids or anions and the solid may be dried at a temperature between 0 and 500 degrees C, with or without vacuum application.

The conditions for the present invention depend on the type of heteropoly acid, the nature of the metal complexes and the variety of the reaction mixture. More particularly, the temperature may be between -80 and 250 ° C, while the pressure may range between 100 and 10-5 bar (a).

The types of chemical reactions contemplated in the context of the present invention are generally reductions, oxidations, coupling reactions, addition reactions, elimination reactions and preferably (chiral) hydrogenations, (chiral) hydrogen transfer reactions, CC coupling reactions ( Heck, Suzuki, Stille, allyl substitutions, metatheses, polymerizations, etc.), catalyzed oxidations, (chiral) epoxidations, etc. In a preferred embodiment such chemical reactions are homogeneously catalyzed reactions.

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- 19 Examples

Preparation of silicotungstic acid modified alumina

150 grams of alumina (230 m²150 micron particles) were suspended in 500 ml technical grade ethanol. 32.95 grams of silicotungstic acid was dissolved in 100 mL of ethanol and added dropwise to the stirred alumina suspension for 1 hour at room temperature. After 14 hours the stirring was stopped and after a further 2 minutes the upper layer was decanted off. The remaining solids were washed several times with 1 L portions of demi H₂O to remove any unsupported silicotungstic acid. The solids were dried at 200 degrees C. Analysis with ICP showed that the alumina contained 11.7 wt% tungsten, which is equivalent to 18.0 wt% silicotungstic acid.

Catalyst Removal Removal [Rh ((R, R) -MeDuPHOS) (OOP)] BF₄

12.6 mg [Rh ((R, R) -Me-DuPHOS) (COD)] BF₄ (21 micromoles) were dissolved in a 20 mL methanol solution containing 6.33 grams of dimethyl itaconate (40 mmol) under a nitrogen atmosphere. The slightly orange colored solution was transferred to a hydrogenation reactor. The reaction mixture was purged with H₂. The reaction mixture was stirred under a pressure of

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20 psig hydrogen for two hours at room temperature (22 degrees C).

A column (3.7 cm high, 1.3 cm diameter) was loaded with 5.06 grams of silicotungstic acid modified alumina (18.0 wt% silicotungstic acid as determined by ICP). After two hours, the orange colored solution was transferred from the reactor to the top of the column. A colorless solution was collected at the bottom of the column containing 6.01 grams (95% yield) of the enantiomeric high purity hydrogenated product (97.5% enantiomeric excess (ee) as determined by Chiral GC). The colorless solution contained less than 10 micrograms of rhodium and less than 10 micrograms of tungsten. The orange color remained on the column. The column solids appeared to contain 11.7 wt% tungsten and 0.04 wt% rhodium (determined by ICP). Presumably Rh originates from the remains of the catalyst [Rh ((R, R) -Me-DuPHOS) (COD)] BF4.

Catalyst Removal Removal [Ru ((P) -BINAP) Cl₂] .NEt₃

The catalyst precursor [Ru ((P) BINAP) Cl₂] .NEt₃ was prepared as described by King et al. in J. Org. Chem. 1992, 57, 6689-6691. The catalytic test was also performed as described in this article using

18.2 mg of [Ru ((P) -BINAP) Cl₂] .NEt₃ (21 micromoles), 44 micromoles HCl, 6.97 grams of butylacetoacetate (42.9 mmol) and 13 mL MeOH.

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A column (7.5 cm high, 1.3 cm diameter) was loaded with 10.0 grams of silicotungstic acid modified alumina (18 wt% silicotungstic acid as determined by ICP). After 12 hours hydrogenation of t-butylacetoacetate was completed and the orange colored solution was transferred from the reactor to the top of the column. A slightly yellow colored solution was collected at the bottom of the column containing 6.46 grams (39 mmol, 91% yield) of t-butyl-3-hydroxybutyrate, the hydrogenated product, in high enantiomeric purity (ee 98%, chiral HPLC ). The lightly colored solution also contained 109 micrograms Ru (5% of the total amount of ruthenium) and less than 10 micrograms tungsten (determined by ICP).

Lisbon, 4th December 2007

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