WO1999000445A1

WO1999000445A1 - Method for discolouring a product, in particular silicon fluid, comprising coloured catalytic residues

Info

Publication number: WO1999000445A1
Application number: PCT/FR1998/001369
Authority: WO
Inventors: Gérard Mignani; Stefan Breunig
Original assignee: Rhodia Chimie
Priority date: 1997-06-27
Filing date: 1998-06-26
Publication date: 1999-01-07
Also published as: AU8345298A; FR2765215B1; FR2765215A1

Abstract

The invention concerns a method for discolouring a product obtained by homogeneous catalytic reaction whereby the catalyst used is a metal selected among the group comprising: palladium, cobalt, platinum, nickel and their mixtures, said product containing coloured metal agglomerates. The method consists essentially in (1) oxidising the metal(s) M constituting the agglomerates, and (2) trapping the resulting oxidised metal forms (Mox) using at least one ligand L carrying free electronic doublet(s), selected among the phosphorous compounds, and/or the nitrogenous compounds, and/or the sulphurous compounds.

Description

PROCESS FOR DECOLORING A PRODUCT, PARTICULARLY A SILICONE OIL, COMPRISING COLORED CATALYTIC RESIDUES.

The field of the present invention is that of industrial products obtained by a homogeneous catalytic reaction, in which the catalyst used is a metal from group VIIIB, in particular, cobalt, palladium, platinum, nickel and their mixtures.

Given their mode of production, these products have the undesirable characteristic of being colored, due to the presence within them of catalytic residues formed by colored metal agglomerates.

The present invention relates to the discoloration of such products. The reactions in which these metal catalysts take part are, for example, hydrosilylations catalyzed with platinum, quite conventional in the field of silicone oils, dehydrogenocondensations, or alternatively hydrogenations catalyzed with nickel or palladium such as those encountered in the context of the production of hydrogenated polysaccharides from non-hydrogenated polysaccharides (sugars), in the context of the reduction of aromatics to aliphatics, in the context of the hydrocyanisation of unsaturated, or in the context of hydroformylation, etc. As regards the field of silicones, hydrosilylation is commonly used to functionalize silicone oils carrying SiH units, by reacting the latter with the unsaturations carried by precursor synthons of functionalization grafts. Hydrosilylation is actually an addition reaction. The unsaturation of the functionalizing building blocks is of olefinic, in particular α-olefinic, vinylic, allylic or acetylene type. By way of example of olefinic synthons, mention may be made of those belonging to the family of alkenes, styrenes, allyl alcohols, allyl oxyethers or allyl amines. In the silicone industry, the functionalizing synthons that are encountered for example are allyl-glycidyl ether, 1,2-epoxy-4-vinyl-cyclohexane, vinyltriethoxysilane, 1-octene, allyloxyether.

The silicone oils capable of hydrosilylating these olefinic synthons are for example POSs of formula:

- Me3SiO- (MeHSiO) _n - (Me2SiO) _m - SiMe3 in which n and m are whole or fractional numbers such as 1 <n <1000 and 0 <m <1000; - Me ₂ HSiO- (MeHSiO) ₀ - (Me2SiO) _p - SiHMe ₂ in which o and p are whole or fractional numbers such as 0 <o <1000 and

0 <p <1000.

Generally, these hydrosilylation reactions are carried out by homogeneous catalysis for the synthesis of functionalized silicone oils, suitable for many fields of application such as anti-adhesion, in particular paper anti-adhesion, lubrication, base polymers. , adhesion modulators or silicone elastomer compositions.

Many catalytic compositions are used in hydrosilylation reactions. The most well-known catalytic compositions contain metals such as platinum, rhodium, cobalt or palladium. Specific examples of such catalytic compositions are platinum halides and rhodium halides, for example H ^ PtClg PtCl2, (RhCl3, xH2θ) platinum complexes with siloxanes having unsaturated groups, platinum complexes with olefins and cationic complexes of platinum with nitriles as ligands.

Generally, the catalytic compositions used in the hydrosilylation reaction are homogeneous catalytic compositions, i.e. they are dissolved in the reaction medium. One of the most used is the catalytic composition of Karstedt described in particular in US Patent 3,775,452. This Karstedt composition is made up of platinum complexes whose formal and real degree of oxidation is zero (0) and of formula:

It is observed that these functionalized silicone oils, obtained from processes using homogeneous catalysis are generally colored, with a coloration greater than 60 Hazen; which therefore limits their possible fields of use, in particular in the field of colorless and / or transparent films (for example of the non-stick type for paper), in the field of inks, and / or in the field of varnish. This coloring is generally due to the presence in functionalized oils of metal aggregates or colloids of manometric size, derived from homogeneous catalytic compositions used in hydrosylilation processes. The discoloration of these silicone oils requires additional filtration and purification steps to be able to be used after crosslinking in the field of transparent films.

These additional steps make industrial implementation complex, expensive and therefore not economically viable.

In particular, techniques are known for bleaching silicone oils functionalized by homogeneous hydrosilylation with platinum, consisting in passing these oils immediately after their obtaining onto or through amino resins. This percolation is necessarily followed by a long and difficult filtration step, to remove the fines which the oil has taken up in the resin. Another technique consists in agitating the colored functionalized oils, immediately after their production, in the presence of amino resins to promote contact. Then, a filtration step is necessary. It is easily understood that, given the viscous nature of these silicone oils, these 2 techniques, chromatographic and stirring, of discoloration with resin are long and expensive. In addition, these techniques which are more laboratory techniques than industrial processes have the disadvantage of being particularly inconvenient due to the pestilential odors which emanate from amino resins.

The prior art is no more provided as regards, more generally, all the products obtained by means of a reaction involving a homogeneous metallic catalyst chosen from the group consisting of palladium, cobalt, platinum, nickel and their mixture, and which would benefit from comprising only an extremely reduced or even zero quantity, of colored residual agglomerates comprising the catalyst. Faced with such a deficiency in the state of the art, in terms of a satisfactory solution to the problem of discoloration, the applicant set itself the objective of developing a process for discoloration of a product obtained by a homogeneous catalytic reaction involving a metal chosen from the group consisting of palladium, cobalt, platinum, nickel and their mixtures as catalyst, in order to tend towards a reduction in coloring, preferably an absence of coloring and, moreover, a clarity and a the highest possible product transparency.

Another objective of the present invention is to provide a new bleaching process which is simple to implement and inexpensive, so as to be adapted to industrial constraints of productivity and profitability. Another essential objective of the invention is to provide a process for bleaching catalytic reaction products involving metals from the group defined above, which is based on the elimination of residual metallic colored agglomerates and which, therefore, reduces toxicity correlatively to optical density.

Another objective of the invention consists in providing a bleaching process which can be implemented either immediately after the synthesis of the products or after storage of said products without loss of performance of the bleaching process. Having set these objectives, the plaintiff had the merit, in the vacuum of the prior art, to observe, after long and laborious research and experiments, that it was advisable to ligand the metallic catalytic residues, having taken care, beforehand, to place these in a ligandable form and to do this, to make them pass from their oxidation state 0 in which they are at the end of the reaction, to an oxidation level higher than 0.

This is how the present invention relates to a process for bleaching a product obtained by a homogeneous catalytic reaction in which the catalyst used is a metal chosen from the group comprising: cobalt, palladium, platinum, nickel and their mixtures, said product thereby comprising colored metal agglomerates, characterized in that it consists essentially

- 1 - oxidizing the metal or metals constituting the agglomerates,

- 2 - trapping the oxidized metallic forms (Mox) thus obtained using at least one ligand L, selected from phosphorous compounds comprising at least one phosphorus atom carrying at least one free electronic doublet, and / or among nitrogen compounds comprising at least two nitrogen atoms each carrying at least one free electronic doublet, and / or among sulfur compounds comprising at least two sulfur atoms each carrying at least one electronic doublet free, steps 1 and 2, preferably being substantially simultaneous,

Optionally separating the complexes [L, Mox] thus formed from the treated product,

- 4 - and optionally devolatilize the bleaching medium before and / or after possible separation of the complexes [L, Mox] according to step 3. This process is an easy-to-apply technique to remove the product-specific coloration of the considered homogeneous catalytic reactions.

The inventive concept at the base of this discoloration, proceeds from the selection of ligands capable of forming with the residual metallic catalysts, colorless and stable complexes, while providing, by the play of an oxidation, to put the metals to be complexed under form of metal-cation with a degree of oxidation greater than 0, so as to favor the formation of non-colored organometallic complexes.

Knowing moreover that the oxidized state of the metals chosen from the group consisting of palladium, cobalt, platinum, nickel and their mixture is ephemeral, a preferred operating protocol according to the invention will be to ensure that there is a certain concomitance between oxidation (1) and trapping (2) by ligandage or complexation.

The uncolored organometallic complexes [L, Mox] can be soluble or insoluble (precipitated) in the bleaching reaction medium. In the latter case, it is easy to eliminate the complexes [L, Mox] precipitated by any known and appropriate separation technique, such as for example a density gradient separation technique such as decantation, filtration, and / or centrifugation. The devolatilization step (4) is optional. Its purpose is to remove from the bleaching reaction medium, the reaction auxiliaries such as, for example, solvents, such as water, as well as volatile products which one does not wish to see present in the discolored product.

The discoloration treatment according to the invention leads to perfectly clear, colorless and stable products, since all traces of colored residual catalytic metal have been removed by trapping with judiciously chosen ligands.

There are numerous industrial reactions of homogeneous catalysis involving a metal from the group consisting of palladium, cobalt, platinum, nickel and their mixture, capable of being found as a colored metallic residue in the reaction product. Hydrosilylations for the grafting of functional synthons are known in particular on silicone oils carrying a SiH motif, dehydrogenocondensations of organohydrogensiloxanes with an alcohol, sugar hydrogenations for the production of polyols, reductions of aromatics to aliphatics, hydrocyamsations of unsaturated (preparation of adiponitrile from butadiene), or even hydroformylations, etc. Without this being limiting, we will focus more specifically in this presentation on the functionalized silicone oils obtained by dehydrogenocondensation and / or, by hydrosilylation of functional synthons, using a precursor silicone oil, carrying SiH functions , in the presence of a homogeneous catalytic composition comprising platinum.

In any case, as soon as a product has colored residues formed by agglomerates composed of one or more metals from the group consisting of palladium, cobalt, platinum, nickel and their mixture, and having served as catalyst, the bleaching process according to the invention is effective and can be implemented with some methodological adaptations within the reach of the skilled person.

As regards the silicone-precursor oils of the functionalized colored oils capable of being treated by the process according to the invention, polyorganosiloxane oils of any kind may be chosen as long as they comprise SiH, but POS diorganohydrogensiloxane oils will be preferred linear or cyclic, and more preferably still, those having as average formula:

and or

in which :

¹ the symbols R _α are identical or different and correspond to a monovalent hydrocarbon radical chosen from the phenyl radical and the linear or branched alkyl radicals having from 1 to 6 carbon atoms, preferably from 1 to 3 carbon atoms; "the symbols X are identical or different and correspond to a monovalent radical chosen from R _α , a hydrogen atom, a methoxy radical, and an ethoxy radical;

"a and b are whole or fractional numbers, such as: - 0 <a <1000, preferably 0 <a <99

- 0 <b <1000, preferably 1 <b <100, and at least one of the two X corresponding to the hydrogen radical if b = 0;

- 1 <a + b <1000, preferably 1 <a + b <100

"c and d are whole or fractional numbers, such as - 0 <c <20, preferably 0 <c <4

- 1 <d <20, preferably 1 <d <5,

- 3 <a + b <20, preferably 3 <a + b <5

The synthons capable of reacting with these silicone-precursor oils carrying SiH are short-chain hydrocarbon molecules carrying at least one unsaturated graft leg or end (alkenyl-alkynyl) and at least one function intended to confer properties specific to silicone oils, suitable for different applications of these oils.

Preferably, the grafting legs of these synthons are of the ethylenic type.

(vinyl, allylic). The other function of synthons can be:

- linear or branched alkenyl or alkenyloxy, at least in C ₄ , preferably in C ₄ -C ₁₂ , by way of examples, mention may be made of 3-butenyl, 5-hexenyl, 9-decenyl, 10-undecenyl, 16 , 1 -heptadecenyl, 5,9-decadienyl, 6.1 1- dodecanedienyl, allyloxypropyl, etc. - reactive polar: capable of reacting either chemically by hydrolysis, esterification, condensation, polycondensation, addition, and / or polyaddition, etc. , or by dipolar interaction, preferably chosen from groups which may contain from 1 to 20 carbon atoms, and even more preferably from those listed below: lactones; anhydrides; halides; nitriles; esters; nitrosos; sulfones; thioethers; hydroxides [ex: 3-hydroxypropyl, 3- (2-hydroxyethoxy) propyl, etc.]; epoxides [ex: 3-glycidoxypropyl, 4-ethanediyl 1,2-epoxycyclohexyl, etc.]; alkoxides [ex: methoxy, ethoxy, butoxy, octyloxy, etc]; aryloxides [ex

: phenyloxy, etc.]; acyloxides [ex: acetoxy, etc.]; alkenylcarbonyloxides [ex: acrylyloxy, methacrylyloxy, etc.]; trialcoxysilyles [ex: -CH ₂ -CH ₂ -Si- (OC ₂ H ₅ ) ₃ etc], The functionalizing synthons can be chosen from products having at least one hydrocarbon ring in which an oxygen atom is included and which have the formula:

O)

in which :

"the symbols W are identical or different and correspond to a divalent hydrocarbon radical chosen from linear or branched alkylene radicals having from 1 to 12 carbon atoms, one of the symbols W being able to be a free valence;" the symbol Y corresponds to a valence free or a divalent radical chosen from linear or branched alkylene radicals having from 1 to 12 carbon atoms and which may contain a heteroatom, preferably an oxygen atom;

"the symbol Rp corresponds to a hydrogen atom or monovalent hydrocarbon radical chosen from linear or branched alkyl radicals having from 1 to 12 carbon atoms, and preferably a hydrogen atom or a methyl radical;

in which :

"the symbols W are identical or different and correspond to a divalent hydrocarbon radical chosen from linear or branched alkylene radicals having from 1 to 12 carbon atoms, one of the symbols W can be a free valence;

"the symbol Y corresponds to a free valence or a divalent radical chosen from linear or branched alkylene radicals having from 1 to 12 carbon atoms and which may contain a heteroatom, preferably an oxygen atom;

¹ the symbol Rp corresponds to a hydrogen atom or monovalent hydrocarbon radical chosen from linear or branched alkyl radicals having from 1 to 12 carbon atoms, and preferably a hydrogen atom or a methyl radical;

(3)

in which : "the symbols W are identical or different and correspond to a divalent hydrocarbon radical chosen from linear or branched alkylene radicals having from 1 to 12 carbon atoms and which may contain at least one hydroxyl function; one of the symbols W may be a free valence for (V) and the two symbols W can be simultaneously a free valence for (VI);

"the symbols W are identical or different and correspond to a divalent hydrocarbon radical chosen from linear or branched alkylene radicals having from 1 to 12 carbon atoms; at least one of the symbols W can be a free valence;

4)

in which :

"the symbols W are identical or different and correspond to a free valence and a divalent hydrocarbon radical chosen from linear or branched alkylene radicals having from 1 to 2 carbon atoms;

"the symbol Z corresponds to a divalent radical chosen from a carbon atom or a heteroatom. Preferably, the hydrocarbon ring in which the hydrogen atom is included has at most 8 atoms in said cycle. In particular, the synthons used have the formula:

= O

O

(X),

In general, the synthons reacting with the silicone oil are identical synthons. The molar ratio of the silicone oil / synthons is between 0.01 and 100, preferably between 0.1 and 10. In the case of the hydrosilylation of ethylenically bridged synthons, the homogeneous metal catalysts used are conventionally Karsted catalytic compositions such as those described in patent US Pat. No. 3,775,452. It can also be a catalyst for platinum bis-benzonitrile dichloride type, platinum bis-diethyl sulfite dichloride type catalyst, or dicobalt octacarbonyl type catalyst, etc.

In the Karstedt catalyst, platinum is ligated into a complex comprising vinylated disiloxanes. Its oxidation degree is equal to 0. The hydrosilylation of the vinyl functions by the SiH units of the precursor silicone oil causes the release of the ligated platinum, so that the latter is found in the form of free Pt of degree d oxidation 0 in the reaction medium at the end of the hydrosilylation reaction. And it is this free Pt ° which agglomerates into particles of a few nanometers formed of about 55 atoms, a source of coloring.

According to an advantageous embodiment of the invention, according to step (1), oxidation of the catalytic metal or metals is carried out, using an oxidant chosen from the following group:

^ H _J O _J , hydroperoxides (e.g. t-butyl-hydroxyperoxide), dialkylperoxides, diarylperoxides, ketones peroxides, acylperoxides, peresters, peroxycarbonates, and mixtures thereof. This oxidant must be chosen so that it can allow the transformation of the coloring metal (s) from their metal form with oxidation state 0 to their oxidized form of metal-cation. As regards platinum, the degree of oxidation reached is + II, or even + IV.

Once in the oxidized form, the metal cation originating from the catalyst is complexed by one or more ligands L which, in accordance with a preferred characteristic of the invention, are selected from the following group of products:. at.

PR „

Δ the radicals R of these formulas a ,, a _j and a ₃ being identical or different from each other and corresponding to linear or branched C _r C ₁₈ alkyls, cycloalkyls, C ₂ -C ₁₈ alkenyls, linear or branched , aryls, aralkyls, alkylaryls, with the condition that R ≠ halogen;

Δ the radicals R ¹ of the formulas d ^ and a ₃ being identical or different from each other and representing C 1 -C ₁₀ alkyls or cycloalkyls;

Δ m being an integer between 1 and 20 preferably between l and 10

Δ n being an integer between 1 and 5 preferably 1;

Δ the radicals R ² of these formulas b, and b ₂ being identical or different and corresponding to the same definition as that given above for R in the formulas a _j and a ^ Δ the radicals R ³ of the formula b _j being identical or different and corresponding to the same definition as that given above for R ¹ in the formula ^, Δ p and q being whole numbers between 1 and 20 preferably between 1 and 10

• b.

Δ the pyridyl residues of these formulas b ₃ , b ₄ and b ₅ being optionally substituted by identical or different radicals R ⁴ , each representing a linear or branched C ₁₀ -C ₁₀ alkyl, a cycloalkyl, an aryl, an aralkyl, an alkylaryl. Δ the radicals R ⁵ of this formula b ₄ corresponding to the same definition as that given above for the R ² of the formula b ₂ , Δ u is an integer between 1 and 20, preferably between 1 and 10. Δ 1 , w and v are integers other than 0. (for example, the product Reilleux 402 from the company REILLY). Δ r being an integer between 1 and 20, preferably between 1 and 10,

• vs.

c ₂

R ⁶ S t SR ⁶

Δ the radicals R ⁶ of the formulas c, -c ₂ being identical or different and corresponding to the same definition as that given above for R in the formulas a, and a ^; Δ the radicals R ⁷ of the formula c, being identical or different and corresponding to the same definition as that given above for R ¹ in the formula ^, Δ s and t being whole numbers between 1 and 20, preferably between 1 and 10, • d - and the mixtures of the above ligands L a ,, a ^, a ^, b ,, b ₂ , b ₃ , b ₄ , b ₅ ,

^C >1> ^C 2

As examples of preferred type A phosphorous ligands, mention may be made of phosphines, bi-phosphines, polyphosphines, and divynilbenzene polystyrenes containing phosphine functions, etc. ; triphenylphosphine being particularly preferred.

As examples of preferred type b amino ligands, mention may be made of products of the bi or polypyridine type, the amino pyridines, the alkyl alkylene poly (di) amines such as tetramethylethylene diamine, the poly-4-vinylpyridine, the poly - 4-vinylpyridine- co-divinylbenzene, etc. ; ® ° As examples of preferred type c sulfur ligands, there may be mentioned thioethers, mercaptoethyl sulfides, α, ω-alkyl-dithiol, diethylene-dithio glycol, 1,3-dithiane, etc.

The number of ligands associated with a metal atom (for example of platinum), in a complex, will obviously depend on the nature of the ligand, of the trapped metal and on its degree of oxidation. In the case of platinum, a metal atom can be linked, for example, with 1 to 4 ligand molecules.

According to a first embodiment of the process in accordance with the invention (homogeneous approach), the bleaching is carried out using one or more ligands L used in solid form or in form dissolved in a solvent formed by water and / or an alcohol and / or an organic solvent such as toluene or xylene, and / or a silicone of low molar mass such as hexamethylsiloxane. In this first embodiment, the ligand is not linked to a support. Once the oxidation / trapping reaction is complete in this first mode of implementation, the reaction medium is advantageously devolatilized to remove the low boiling point silicones and the water, which is a source of turbidity for the oil. After cooling, the devolatilized reaction medium can be filtered, so as to remove any precipitates which may have formed there. It can be in particular complexes [L, Mox],

In accordance with a second mode of implementation (heterogeneous approach), a ligand L supported, preferably on resin, is used, the latter being advantageously constituted by one or more crosslinked homo or copolymers, more especially selected from the following group: polystyrenecodivinylbenzene,

• polyvinylpyridinecodivinylbenzene,

• polyvinylpyridine,

• polyorganosiloxanes (silicone resin comprising siloxyl units Q and optionally M and / or D and / or T). These carriers carrying the metal ligand are preferably polymeric resins, which are not soluble in the bleaching reaction medium. Like the first embodiment, the bleaching reaction according to the second embodiment can be carried out in bulk or in a solvent such as water and / or an alcohol and / or an organic solvent, such as, for example, toluene or xylene. In such a case, where the ligand L is fixed on a non-soluble support, a complexing of the coloring metal is observed, present in the medium with the ligands fixed to the support. This leads to a very effective discoloration of the treated product. The insoluble support loaded with complexes is easily separable from the discolored liquid product.

To prepare ligand supports, solid and not soluble in the discoloration medium, it is possible:

reacting the ligand L with a crosslinked or non-crosslinked polymer resin,

- And / or use comonomers constituted by the ligands in themselves intrinsically carrying polymerization functions

(ex: vinylpyridine) and / or obtained by connecting the ligand to a comonomer (ex: bromostyrene).

These homo or copolymer support resins are crosslinked, for example, by radical route or by condensation route. The level of crosslinking of the resins is chosen so that the space in the vicinity of the supported ligand is not too great. The ligand thus remains accessible to metal.

The level of crosslinking of the support resins is such that the glass transition temperature of the resin is preferably greater than 40 ° C. In practice, it is not necessary for the support resin to have a consistency or a mechanical strength during the discoloration reaction. However, it is preferable for it to be in solid form at the end of the reaction, so as to promote the separation of the [L, Mox] complexes from the medium to be discolored.

As other examples of resins which are particularly suitable as a support for the ligand, mention may be made of polystyrene resins and / or polyvinylpyridine resins, etc.

At the end of steps 1 and 2 of oxidation and trapping in the second embodiment, the reaction medium is filtered to remove the support comprising the ligands themselves complexed with the metal, at the origin of the coloring. The low boiling point silicones and water are then removed by devolatilization. The water source of heterogeneity of the medium, favors during devolatilization the elimination of volatile compounds from the oil by steam entrainment. The filtered and devolatilized oil which is recovered after cooling is no longer colored due to the presence of metal and in particular of platinum. As regards the stoichiometry of the process according to the invention, preferably: Between 10 and 10 ⁶ preferably between 100 and 10 ⁵ and more preferably still between 10 ³ and 10 ⁴ mol% of oxidant relative to the metal, preferably Pt,

• between 1 and 10 ⁵ preferably between 10 and 10 ⁴ and more preferably still between 50 and 5000 mol% of ligand L relative to the metal, preferably platinum. In the particular case where the product to be discolored is a functionalized silicone oil and where the pollutant-dye is a metal with an oxidation state of 0, preferably platinum, the following are used per 100 parts by dry weight of silicone oil:

more than 1.10 " ³ to 100 parts by dry weight of oxidant, preferably H ₂ 0 ₂ , more than 1.10 ^-3 to 10, preferably 5.10 ' ³ to 3 parts by dry weight of

Ligand L. To detail somewhat the methodology adopted in practice for the method according to the invention, it will be indicated, without this being limiting, that:

- the reaction medium for the discoloration is the seat of the oxidation

M - Mox and concomitant trapping [L, Mox], at a temperature between 50 and 160 ° C, depending on the oxidant used, preferably between 60 and 80 ° C with H ₂ 0 ₂ , - we put this medium with stirring for at least part of the oxidation / trapping, the duration of which is preferably between a few minutes and several hours. This is how the reaction temperature is for example 80 ° C. for a reaction time of 1 to 24 hours. The devolatilization which can succeed oxidation / trapping, is carried out by taking the discoloration medium to a higher temperature. at 70 ° C, for example of the order of 120 ° C, for a few minutes (30 min). The product is then allowed to cool, which is then filtered; the discolored product is obtained which also has improved transparency and clarity (that is to say a turbidity <1 NTU).

According to a variant of application of the discoloration according to the invention, which may fall under either the first or the second mode of implementation, the process is carried out discontinuously and for this, a solution of ligand L is produced in the medium. or a dispersion of particles insoluble in the medium and comprising the ligand L fixed or not on a support, these particles preferably being formed by crosslinked (co) polymer support beads and comprising the ligand L. According to another variant which can only be registered in the context of the second embodiment using a supported ligand, discoloration is carried out continuously, using at least one fixed bed or fixed support comprising the ligand L , and preferably consisting of at least one column comprising a liganding resin, and the product to be bleached and the oxidant is percolated through and / or on this bed or this column.

This variant corresponds to an industrial bleaching scheme, according to which the product, in particular the oil to be bleached, is percolated continuously, through one or more chromatographic columns loaded with ligand-carrying resin capable of complexing the oxidized metal.

It follows that according to another of these aspects, the present invention relates to a bleaching device which can be used for the implementation of the method described above and characterized in that it comprises at least one fixed bed or fixed support containing the ligand, and designed so that the product to be discolored can percolate through and / or on this bed with a fixed support, the latter preferably being formed by a percolation column comprising ligand resin.

The method and the device according to the invention make it possible to achieve remarkable performance in terms of discoloration. Indeed, the treated products (in particular the functionalized silicone oils) are almost colorless, have a coloration of the order of 3 to 60 Hazen.

Whatever the degree of coloration of the products to be treated, the method according to the invention makes it possible to achieve a discoloration rate at least equal to 50%. Furthermore, discolored products have, by definition, a very low metal content from the homogeneous catalytic composition. This very much limits the undesirable reactions that the metal could cause if it were present in larger quantities. For example, in the case of a functionalized silicone oil obtained using a catalytic composition homogeneous with platinum and treated by the process according to the invention, it is now possible to mix this oil with other molecules containing SiH functions and molecules containing unsaturated bonds, without risking new hydrosilylation reactions between these molecules.

It should also be noted that the bleaching process described above is economical and easy to implement. Finally, it has the advantage of not disturbing the other physicochemical characteristics of the products to be discolored and in particular of silicone oils functionalized by hydrosilylation of unsaturated synthons.

The examples which follow will make it possible to better understand the invention and to understand all these advantages and its variants of implementation.

Examples

Examples 1 to 4 which follow illustrate the first mode of implementation, corresponding to the case in which the ligand L is not supported on an insoluble resin.

Examples 7 to 20 relate to the second embodiment, in which the complexing ligand (s) of the oxidized metal are fixed on a support formed by an insoluble resin.

The coloration of the functionalized oils obtained is measured using a "liquid-tester LTM1" device from Dr. Lange using two rays for the measurement in transmission.

The turbidity of the functionalized oils obtained is measured using a Hack turbidimeter by light dispersion (measurement by ratio). For all of the oils treated according to the process of the present invention, the turbidity measured is less than 1 NTU.

The platinum content of the functionalized oils obtained is measured by ICP-MS. The viscosity of the functionalized oils obtained is measured using a Brookfield device according to the dynamic method (by shearing).

PLE EXE l: SBR181

A 250ml balloon is loaded with

- 10g of POS A oil of 342 Haz coloring and of the type below in which x = 283 and

- 25g of hydrogen peroxide

- and one gram of triphenylphosphine.

Stirring is carried out by a magnetic bar. The mixture is heated at 80 ° C. for 3 hours with vigorous stirring. After cooling at room temperature, filter on cardboard to remove the insoluble triphenylphosphine. After filtration, the phases are separated. After devolatilization, to remove the remaining water, the product is clear and colorless (14Haz) The viscosity is unchanged. After cooling to 4 ° C for one hour, it is filtered to remove the reprecipitated triphenylphosphine

EXAMPLE 2 SBR183

A 250ml flask is loaded with 120g of POS A oil in which x = 70 and y = 7, of 103Haz coloring, 2g of hydrogen peroxide and 0.3 g of triphenylphosphine Stirring is carried out by a magnetic bar The mixture is heated at 80 ° C for 3 hours with vigorous stirring After cooling to room temperature, filter on cardboard to remove the insoluble triphenylphosphine. After devolatilization, to remove the remaining water, the product is clear and little colored (38Haz) The viscosity is unchanged After cooling to 4 ° C for one hour, it is filtered to remove the reprecipitated triphenylphosphine

EXAMPLE 3. SBR184

A 250ml flask is loaded with 60g of POS A oil in which x = 70 and y = 7, 103 Haz coloring, 21 mg of hydrogen peroxide and 485 mg of triphenylphosphine Stirring is carried out by a magnetic bar The mixture is heated at 80 ° C for 3 hours with vigorous stirring After cooling to room temperature, no no precipitation. After devolatilization to remove the remaining water, the product is clear and slightly colored (51 Haz). The viscosity is unchanged. After cooling to 4 ° C for one hour, no precipitate is observed.

EXAMPLE 4: SBR178

A 250ml balloon is loaded with:

- 100g of POS B oil of the type (M-D7 _υ - (D ^X ) 7-M in which D ^x = SiO (Me) (ethylcyclohex-3-ene) and having a coloration amounting to 830 Haz, - 30g of hydrogen peroxide and 2g of triphenylphosphine.

Agitation is carried out by a magnetic bar. The mixture is heated at 70 ° C for 3 hours with vigorous stirring. After cooling to 0 ° C., 100 ml of diethyl ether are added. After separation of the phases, the organic phase is devolatilized and filtered at 0 ° C. on cardboard to remove the insoluble triphenylphosphine. The product is clear and colorless (1 lHaz).

COUNTER EXAMPLE 5: SBR180

A 100ml flask is loaded with 10g of POS A oil in which x = 283 and y = 5, of coloring 342 Haz and lg of triphenylphosphine. Agitation is carried out by a magnetic bar. The mixture is heated at 80 ° C for 3 hours with vigorous stirring. After cooling to room temperature, filter on cardboard to remove the insoluble triphenylphosphine. After devolatilization, to remove the remaining water, the product is clear but colored (108Haz). The viscosity is unchanged. After cooling to 4 ° C. for one hour, it is filtered to remove the reprecipitated triphenylphosphine.

COUNTER EXAMPLE 6: SBR179

A 100ml flask is loaded with 10g of POS A oil in which x = 283 and y = 5, 342 Haz coloring and 10g of hydrogen peroxide at 30%. Agitation is carried out by a magnetic bar. The mixture is heated at 80 ° C for 3 hours with vigorous stirring. After cooling to room temperature, the phases are separated using pentane as solvent for the oil. After devolatilization, to remove the solvent and the remaining water, the product is clear but colored (244Haz). The viscosity is increased from 600 to 870 cps and a gelled part is observed. EXAMPLE 7: SBR192

A 250ml balloon is loaded with:

- 60g of POS A oil in which x = 70 and y = 7, having a coloration amounting to 107 Haz, - 104 mg of hydrogen peroxide (30%) and one gram of triphenylphosphine supported on resin

20% cross-linked polystyrene / Polydivinylbenzene (marketed by the Company

Strem Ref .: 15-6730).

Agitation is carried out by a mechanical agitator so as not to produce fine particles by friction. The mixture is heated at 80 ° C for 3 hours with vigorous stirring. After returning to ambient, it is filtered on cardboard to eliminate the supported triphenylphosphine. Then devolatilize to remove the remaining water. The product is clear and slightly colored (51 Haz). The viscosity remains unchanged.

EXAMPLE 8: SBR194

A 250ml flask is loaded with 60g of POS A oil in which x = 70 and y = 7, 96 Haz coloring, 208mg of hydrogen peroxide (30%) and 0.5g of triphenylphosphine supported on 20% crosslinked Polystyrenecodivinylbenzene resin ( Strem Ref .: 15-6730). Agitation is carried out by a mechanical agitator so as not to produce fine particles by friction. The mixture is heated at 60 ° C for 19 hours with vigorous stirring. After returning to ambient temperature, filter on cardboard to remove the supported triphenylphosphine. Then devolatilize to remove the remaining water. The product is clear and colorless (3 Haz). The viscosity remains unchanged.

EXAMPLE 9: SBR198

A 100ml balloon is loaded with:

- 52g of POS C oil of the M-Dy3fj-D ^z 20-M type in which DY = SiO (Me) (OEt) and D ^z = SiO (Me) (ethylcyclohex-3-ene) and having a coloration s' raising to 595 Haz, - 10g of hydrogen peroxide (30%) and 0.5g of triphenylphosphine supported on resin

Cross-linked 20% polystyrenecodivinylbenzene (marketed by the company Strem

Ref .: 15-6730).

Agitation is carried out by a mechanical agitator, so as not to produce fine particles by friction. The mixture is heated at 80 ° C for 5 hours with vigorous stirring. After returning to ambient, we filter on cardboard to eliminate the triphenylphosphine supported. Then the remaining water is removed by phase separation. The last traces of water are then removed by treatment with anhydrous MgS04. After filtration on cardboard the product is clear and colorless (34 Haz). The viscosity remains unchanged.

EXAMPLE 10: SBR199

A 250ml balloon is loaded with:

- 100g of POS D oil of type M-DY30-D ^U 20-M in which DY = SiO (Me) (OEt) and D ^u = SiO (Me) (octyl) and having a coloration amounting to 120 Haz ,

- lg of hydrogen peroxide (30%)

- and 0.5g of triphenylphosphine supported on 20% crosslinked Polystyrenecodivinylbenzene resin (sold by the company Strem Ref .: 15-6730).

Agitation is carried out by a mechanical agitator so as not to produce fine particles by friction. The mixture is heated at 60 ° C for 14 hours with vigorous stirring. After returning to ambient temperature, filter on cardboard to remove the supported triphenylphosphine. Then the remaining water is removed by phase separation.

The last traces of water are then removed by treatment with anhydrous MgSO_ι.

After filtration on cardboard the product is clear and colorless (38 Haz). The viscosity remains unchanged.

EXAMPLES 1 1 TO 16

In these examples, the functionalized silicone oils to be discolored are: POS C. POS A in which x = 70 and y = 7. The oxidant is H ₂ O ₂ .

Ligand L is triphenylphosphine supported on polystyrene / polydivinylbenzene resin of the type used in examples 7 to 10. The protocol is that given in these examples 7 to 10.

Table 1 below gives the experimental conditions and the results obtained. TABLE 1

* Triphenylphosphine supported on PS / PDVB resin

The results show the good efficacy of the supported phosphine ligands. With phosphines on PS / DVB resin, good discoloration is obtained with 0.1 to 1% by mass of the resin in the medium and an equivalent amount of hydrogen peroxide at 30%.

For a staining of 595 Haz, it takes approximately 1% of ligand and for a staining of 103 Haz it takes approximately 0.1% of ligand in the cases studied.

The influence of temperature is not very important for the final coloring, but for the speed of discoloration. It is decisive for the rate of decomposition of hydrogen peroxide.

An excess of H ₂ 0 ₂ with respect to PPh only causes the oxidation of the phosphine, thus reducing the availability of this ligand. The use of little H ₂ O ₂ is preferable. The best results are obtained with a supported PPh ₃ / H ₂ 0 ₂ mass ratio at 30% of 1/1. Discoloration of a POS A oil containing epoxy functions is possible without a secondary reaction; that is to say that the epoxy functions do not react. analysis

NMR confirms that there is no change in the structure of the oil after treatment.

The discoloration of a POS C oil containing SiO (Et) functions (ethylcyclohex-3-ene) is carried out without a secondary reaction; that is, the sensitive functions do not react. NMR analysis confirms that there is no change in the structure of the oil after treatment.

EXAMPLES 17 TO 19 These are the same conditions as for Examples 11 to 16 above, except for the nature of the ligands and some other experimental parameters given in Table 2 below which also gives the results obtained in terms of coloring

POS A oil is an oil in which x = 70 and y = 7

TMEDA (= Tetra-Methyl-Ethylene-DiAmine) is very interesting and equivalent to 2,2'-Bipyridyl and 2 2'-Dipyridylamine

EXAMPLES 20 AND 21

The experimental conditions are the same as for Examples 11 to 19, except for the ligands which are, in this case, PolyVinylPyridine resins

(PVP) whose crosslinking rates are 2 and 25% respectively Table 3 below gives the experimental conditions and the results obtained in terms of coloring

POS A oil is an oil in which x = 70 and y = 7 TABLE 3

These polyvinylpyridine type resins give excellent results, especially with the 2% crosslinked resin. The platinum ligand functions of this resin are mobile enough to trap the metal well.

Claims

1 - Process for bleaching a product obtained by a homogeneous catalytic reaction in which the catalyst used is a metal chosen from the group comprising: palladium, cobalt, platinum, nickel and their mixtures, said product thereby comprising agglomerates colored metal, characterized in that it consists essentially

- 1 - oxidizing the metal or metals constituting the agglomerates,

- 3 - optionally separating the complexes [L, Mox] thus formed from the treated product, - 4 - and optionally devolatilizing the bleaching medium before and / or after optional separation of the complexes [L, Mox] according to step 3.

2 - Process according to claim 1, characterized in that the product to be discolored is a silicone oil obtained by hydrosilylation of synthons using a precursor silicone oil carrying functions ^ S ⁱ π _{^ in the} presence of a catalytic composition homogeneous comprising platinum.

3 - Method according to claim 1 or claim 2, characterized in that the oxidation of the metal or metals is carried out according to step (1), using an oxidant chosen from the following group: H ₂ O ₂ , hydroperoxides, dialkylperoxides, diarylperoxides, ketones peroxides, acylperoxides, peresters, peroxycarbonates, and mixtures thereof. 4 - Process according to any one of claims 1 to 3, characterized in that the ligand L is selected from the following group of products: • a,

PR.

Δ the radicals R of these formulas a ^ ^ and a ₃ being identical or different from each other and corresponding to linear or branched C _r C _lg alkyls, cycloalkyls, C ₂ -C _{lg alkenyls} , linear or branched, aryls, aralkyls, alkylaryls, with the condition that R ≠ halogen;

Δ the radicals R ¹ of the formulas ^ and a ₃ being identical or different from each other and representing CC ^ alkyls or cycloalkyls;

Δ m being an integer between 1 and 20 preferably between 1 and 10

Δ n being an integer between 1 and 5 preferably 1;

Δ the radicals R ² of these formulas b, and b ₂ being identical or different and corresponding to the same definition as that given above for R in the formulas a _j and a ^, Δ the radicals R ³ of the formulas b, and b ₂ being identical or different and corresponding to the same definition as that given above for R ¹ in the formula a ₁ , Δ p and q being whole numbers between 1 and 20 preferably between 1 and 10;

Δ u is an integer between 1 and 20, preferably between 1 and 10, • b.

•

Δ the pyridyl radicals of these formulas b _3, b ₄ and b ₅ are optionally substituted by radicals R ⁴ are identical or different, each representing a linear or branched C _j -C ₁₀ cycloalkyl, aryl, aralkyl, an alkylaryl,

Δ the radicals R ⁵ of this formula b ₄ corresponding to the same definition as that given above for the R ² of the formula b ₂ ,

Δ r being an integer between 1 and 20, preferably between 1 and 10,

Δ 1, w and v are integers other than 0;

• vs,

R ⁶ SSR t

Δ the radicals R ⁶ of the formulas c, -c ₂ being identical or different and corresponding to the same definition as that given above for R in the formulas a _x and a ₂ ; Δ the radicals R ⁷ of the formula c, being identical or different and corresponding to the same definition as that given above for R ^! in the formula ^, Δ s and t being whole numbers between 1 and 20, preferably between 1 and 10, • d - and the mixtures of the above ligands L a ^ a ^ a ^ bb ₂ , b ₃ , b ₄ , b ₅ ,

^C l> ^C 2.