FR2843391A1 - Preparation of a halogenoalkyldialkylchlorosilane by reaction of a silane with an alkene halide, with recovery of the platinum/iridium based catalyst - Google Patents

Abstract

Preparation of a halogenoalkyldialkylchlorosilane form a silane and sn alkene halide, and recovery of the catalyst metal by distillation of the reaction medium, contacting of the residue comprising by-products and catalyst with a solid adsorbent and finally separation and recovery of the catalyst metal from the adsorbent. Preparation of a halogenoalkyldialkylchlorosilane of formula (I) : Hal-----(R2R3)Si-(CH2))s-Hal ; by the hydrosilylation of a reaction medium comprising a silane (II) : Hal-(R2R3)SiH ; and an alkene halide (III) : CH=CH-(CH2)s-2Hal ; in the presence of an effective quantity of a hydrosilylation catalyst based on a Pt metal ; in which Hal = halogen(Cl, Br or I); R2, R3 = 1 - 6C alkyl or phenyl; s = 2 - 10. After the reaction is completed,(a) the reaction medium is distilled to separate the product (I) from a liquid distillation residue comprising by-products and the Pt metal or derivatives, (b)the residue is contacted with a solid material to adsorb the Pt metal, then (c) the Pt metal is recovered from the adsorbent.

Description

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PROCESS FOR THE PREPARATION OF HALOGENOALKYLDIALKYLCHLOROSILANE
The present invention relates to a process for preparing halogenoalkyldialkylchlorosilane.

 More particularly, the present invention relates to a process for preparing 3-chloropropyldimethylchlorosilane by hydrosilylating dimethylhydrochlorosilane with allyl chloride and a platinum-metal catalyst and recovering said metal.

 In this type of reaction, the quantities of metal of the platinum mine involved are often high in order to obtain a satisfactory yield.

This amount of metal catalyst is generally greater than 30 p.p.m. calculated with respect to the total weight of the reaction mixture. In order for the process to remain economically attractive, it is desirable to be able to recover the metal from the platinum mine so that it can be reused as a catalyst.

 The present invention provides a process for preparing a halogenoalkyldialkylchlorosilane of the above type, comprising a step of recovering the catalytic metal.

The present invention relates in fact to a process for preparing a halogenoalkyldialkylchlorosilane of formula (I):
Hal --------- (R2R3) If --- (CH2) s --- Hal by hydrosilylation reaction of a reaction medium comprising a silane of formula (II):
Hal --- (R2R3) Si-H and an alkene halide of formula (III): CH = CH- (CH2) s-2Hal in the presence of a catalytically effective amount of a d-based hydrosilylation catalyst a metal of the platinum group, formulas in which: the symbol Hal represents a halogen atom chosen from among the chlorine, bromine and iodine atoms, the chlorine atom being preferred, the symbols R 2 and R 3, which are identical or different, each represent a monovalent hydrocarbon group selected from a linear or branched alkyl radical having 1 to 6 carbon atoms and a phenyl radical, and

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 - s represents an integer between 2 and 10 inclusive, said process being characterized in that, finally hydrogenosilylation reaction a) the reaction medium is distilled to separate the formed product of formula (I) from a liquid pellet of distillation comprising the by-products and the metal of the platinum group or its derivatives, b) the pellet formed in a) is brought into contact with an effective quantity of solid substance adsorbing the metal of the platinum group, and c) on separates the adsorbent from the metal of the platinum mine in order to recover said metal.

 The metal of the platinum group is selected from platinum, iridium, palladium, rhodium, ruthenium and osmium, the preferred metal being iridium.

In the context of this preferred arrangement, suitable Ir-based catalysts are in particular: [IrCl (CO) (PPh 3) 2] [Ir (CO) H (PPh 3) 3] [Ir (C 8 H 12) (C 5 H 5 N) P (C6H11) 3] PF6 [IrCl3], nH2O
H2 [IrCl6], nH2O (NH4) 2IrCl6 Na2Cl6Cl6
K2IrCl6
Klr (NO) Cl5 [Ir (C8H12) 2] + BF4- [IrCI (CO) 3] n H2IrCl6
Ir4 (CO) 12 lr (CO) 2 (CH3COCHCOCH3)
Ir (CH3COCHCOCH3) IrBr3
IrCl3 IrCI4
IrO2 (C6H7) (C8H12) Ir.

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Within the framework of the still more preferred arrangement mentioned above, other Ir-based catalysts which are even more suitable are taken from the group of iridium complexes of formula: [Ir (R 4) Hal] 2 ( XI) in which: the symbol R4 represents an unsaturated hydrocarbon ligand comprising at least one carbon-carbon double bond and / or at least one triple bond
C = C, these unsaturated bonds possibly being conjugated or non-conjugated, said ligand: being linear or cyclic (mono or polycyclic), having from 4 to 30 carbon atoms, having from 1 to 8 ethylenic and / or acetylenic unsaturations and optionally comprising one or more heteroatoms such as for example an oxygen atom and / or a silicon atom; the symbol Hal is as defined above.

 Examples of the iridium complexes of formula (XII) which are more particularly suitable are those in the formula of which: # the symbol R 4 is chosen from 1,3-butadiene, 1,3-hexadiene, cyclohexadiene- 1,3, 1,3-cyclooctadiene, 1,5-cyclooctadiene, 1,5,9-cyclododecatriene and norbornadiene, and the following compounds of formula:

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# le symbole Hal représente un atome de chlore.

# The symbol Hal represents a chlorine atom.

di--chlorobis(divinyltétraméthyldisiloxane)düridium, di--chlorobis(ri-1, 5-hexadiene)düridium, di--bromobis(ri-1,5-hexadiene)düridium, di--iodobis(ri-1,5-hexadiene)düridium, di--chlorobis(ri-1,5-cyclooctadiene)düridium, di--bromobis(r-1,5-cyclooctadiene)düridium, di--iodobis(ri-1,5-cyclooctadiene)düridium, di--chlorobis(ri-2,5-norbornadiene)düridium, di--bromobis(ri-2,5-norbornadiene)düridium, As specific examples of iridium complexes which are even more suitable, mention may be made of the following catalysts:

di - chlorobis (divinyltetramethyldisiloxane) dichloride, di - chlorobis (di - 1,5 - hexadiene) drididium, di - bromobis (di - 1,5 - hexadiene) drididium, di - iodobis (di - 1,5 - hexadiene) dichloridium, di - chlorobis (ri - 1,5 - cyclooctadiene) drididium, di - bromobis (r - 1,5 - cyclooctadiene) dichloridium, di - iodobis (ri - 1,5 - cyclooctadiene) drididium, di - chlorobis (α-2,5-norbornadiene) dichloridium, di-bromobis (α-2,5-norbornadiene) dichloride,

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di--iodobis(r-2,5-norbornadiene)düridium.

di - iodobis (r-2,5-norbornadiene) düridium.

 Without departing from the scope of the present invention, at least one hydrosilylation reaction promoter can be used in addition to the platinum-metal-based catalyst.

 As optional promoter (s), mention may be made of: a compound, which may for example be in the form of a ligand or of an ionic compound, taken in particular from the group formed by: organic peroxide; a carboxylic acid; a carboxylic acid salt; a tertiary phosphine; a phosphite such as, for example, an optionally mixed phosphite of alkyl and / or aryl; an amine; a friend of ; a linear or cyclic ketone; a trialkylhydrogensilane; benzothriazole; phenothiazine; a trivalent metal compound (C6H5) 3 where metal = As, Sb or P; a mixture of amine or cyclohexanone with an organosilicon compound comprising one or more group (s) = Si-H; the compounds CH2 = CH-CH2-OH or CH2 = CH-CH2-OCOCH3; a lactone; a mixture of cyclohexanone with triphenylphosphine; an ionic compound such as, for example, an alkali metal or imidazolinium nitrate or borate, a phosphonium halide, a quaternary ammonium halide, a tin halide II.

 The optional promoter (s), when one (or more) is used, is (are) introduced (s) generally at the beginning of the reaction, in the state in which they are located. (nt) either in the form of a premix based on: promoter (s) + catalyst (s); or promoter (s) + all or part of the diorganohalosilane of formula (II); or promoter (s) + all or part of the alkene halide of formula (III).

 The catalyst can be used, and this is another preferred arrangement, in a homogeneous liquid medium, as described in JP-B-2,938,731 and EP-A-1 156 052. In this context, the The reaction can be conducted either continuously, semi-continuously or discontinuously. At the end of the operation, the product of the reaction of formula (I) is separated and collected by distillation of the reaction medium, and it is possible to recover the catalytic metal contained in the liquid distillation pellet thus obtained, said metal being under its original form of catalyst or in a transformed form. According to

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 In the present invention, the liquid distillation pellet is contacted with an effective adsorbent amount of a solid adsorbent.

The solid adsorbent is generally in the form of powder, extruded, granulated or grafted onto a support such as cellulose for example
As a solid adsorbent it is especially recommended to use carbon black; activated carbons; molecular sieves which are most often synthetic zeolites, silicalites or metal aluminosilicates; silicas; activated aluminas; adsorbent fillers based on diatomite and perlite; activated and milled clays based on bentonite and attapulgite; ion exchange resins; or resins of amberlite or amberlystes type.

 The adsorption may be carried out batchwise or batchwise (with powder-type compounds); continuously via a column or through a fixed bed. The contact time can vary from 5 minutes to 10 hours, preferably between 30 minutes and 7 hours in batch. The temperature can vary from 5 to 150 C, preferably from 10 to 30 C.

 The quantity of adsorbent used for activated carbons, molecular sieves, silicas, aluminas as well as mineral adjuvants is strongly linked, on the one hand, to the specific adsorption capacity relative to each of the adsorbents which it is possible to use in the context of the invention and secondly to the implementation parameters such as temperature and the presence or absence of a solvent.

 The adsorption capacity (q) is expressed as the number of moles of platinum metal adsorbed per kilogram of adsorbent used. This amount q is generally between 0.1 and 30, preferably between 0.5 and 20. In the case where the adsorbent is an ion exchange resin, the resin is characterized by a value of exchange capacity which is specific for each grade of resin and which is related to the functionality carried by this resin. This exchange capacity is generally expressed in meq / g for a dry product or in meq / ml on a wet product. These preference resins are used in such a way that the molar ratio between the function carried by the resin and the metal of the platinum group present in the solution to be treated is between 1 and 30, preferably between 1 and 15 and more especially between 1 and 5.

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 The adsorption step can be carried out at atmospheric pressure or under reduced pressure, and optionally in the presence of a solvent which is inert with respect to the hydrogen halide HHal present in the trace state in the middle. It is recommended to use alkanes (preferably C6 and C7), and aromatic solvents (toluene, xylene or chlorobenzene).

 The amount of alkene halide of formula (III) used is preferably 1 to 2 moles per 1 mole of silane of formula (II). As for the amount of catalyst (s) (i), expressed in weight of metal of the platinum group, it is in the range of 1 to 10,000 ppm, preferably ranging from 10 to 2000 ppm and more preferably ranging from 20 to 1000 ppm based on the weight of silane of formula (II).

 The solid adsorbent on the surface of which the catalytic metal is adsorbed is separated from the distillation pellet by any suitable liquid / solid separation means such as filtration, centrifugation or sedimentation. The metal is then separated from the adsorbent by any physicochemical means compatible with said adsorbent.

 According to a preferred variant, the process further comprises, after step a), a step a ') of bringing the liquid pellet into contact with water in the presence, if appropriate, of an organic solvent inert with respect to HHal. formed, to obtain an aqueous phase and an organic phase and to hydrolyze said pellet.

For reasons of ease of implementation, efficiency of the treatment as well as to improve the safety of the process, it is recommended to work with a pre-hydrolysed distillation pellet and then subject it to the adsorption step. The reaction implemented consists in transforming all the SiCI functions present in the silanol silane and SiO 2 siloxane bottoms by bringing an aqueous solution into contact with the distillation flask according to the chemical reactions:
SiHal + H20 - SiOH + HHal
SiOH + SiHal SiOSi + HHal and SiOH + SiOH SiOSi + H20
The hydrolysis can be done in an acidic or basic medium. If the reaction is carried out in an acidic medium, the aqueous solution used as reagent may be pre-acidified (with HHal for example) or consist solely of demineralised water. The pH of the solution then changes during the reaction to values below 7.

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In this case, it is possible to perform a neutralization of the aqueous phase at the end of hydrolysis by adding a base. The hydrolysis is preferably in basic medium so that all HHal is removed. It is recommended to cast the pellet on a foot of aqueous solution. The hydrolysis may be carried out at temperatures ranging from -15 ° C. to 80 ° C. The reaction being exothermic, it is preferred to carry out the casting of the chlorosilane of formula (II) at moderate temperatures of between -10 ° C. and 30 ° C. the temperature may be necessary. The water used for the hydrolysis can be introduced in the form of ice or an ice / salt mixture. At the end of casting of the pellet, the medium obtained is biphasic consisting of an organic phase and an aqueous phase.

 Preferably the water is added in sufficient amount that the HHal formed is not saturated in the aqueous phase.

 Preferentially, the product of formula (I) is 3-chloropropyldimethylchlorosilane, the product of formula (II) is dimethylhydrochlorosilane and the product of formula (III) is allyl chloride. In this case, the hydrogen halide formed is HCl.

 The following examples illustrate the invention without limiting its scope.

présence de 500 p.p.m. de di--chlorobis(1l-1,5-cyclooctadiene)diiridium par rapport au poids de diméthylhydrogénochlorosilane. Dans un réacteur muni d'un agitateur d'un condenseur à reflux et d'un thermomètre. Le diméthylhydrogénochlorosilane est ajouté goutte à goutte au milieu réactionnel pendant 7 heures à une température de 38 C. Le 3chloropropyldiméthylchlorosilane est séparé du milieu réactionnel par distillation et il reste un culot liquide de distillation contenant le catalyseur. C'est ce culot de distillation qui est traité dans les exemples suivants. In the examples below, a hydrosilylation reaction of dimethylhydrochlorosilane with allyl chloride is carried out first.

presence of 500 ppm of di-chlorobis (11-1,5-cyclooctadiene) diiridium relative to the weight of dimethylhydrochlorosilane. In a reactor equipped with a stirrer of a reflux condenser and a thermometer. Dimethylhydrochlorosilane is added dropwise to the reaction medium for 7 hours at a temperature of 38 C. 3chloropropyldimethylchlorosilane is separated from the reaction medium by distillation and a liquid distillation residue containing the catalyst remains. It is this distillation pellet which is treated in the following examples.

Example 1: Iridium recovery on a distillation pellet neither diluted nor hydrolysed with 2% by weight of carbon black: In a one-liter tetracol equipped with mechanical stirring and breathable under argon atmosphere, are introduced 208. 85 g of a distillation residue containing 1. 2% by weight of iridium. The reaction medium is stirred and heated to 60 C.

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4. 235 g of carbon black 2S marketed by CECA are then added and the temperature conditions are maintained for 1 hour. The medium is then filtered under argon pressure on a stainless steel filter (0.5 m). The oil corresponding to the filtrate and the cake are recovered and analyzed in elemental analysis.

The results obtained are summarized in Table 1 below:
ARRAY1

<Tb>
<tb> Examples <SEP> Ir <SEP> ** <SEP> C <SEP> H <SEP> CI <SEP> If <SEP>#
<tb> 33. <SEP> 1
<tb> 1 <SEP> Oil <SEP> before <SEP> treatment <SEP> 1.2 <SEP> 39. <SEP> 3 <SEP> 7. <SEP> 8 <SEP> (32.3) <SE> 17.6 <SEP > 99. <SEP> 8
<tb> *
<tb> Oil <SEP> treatment <SEP> to <SEP> 2%
<tb> 32. <SEP> 2
<tb> mass <SEP> of <SEP> black <SEP> of
<tb> 1 <SEP> 0. <SEP> 83 <SEP> 40. <SEP> 4 <SEP> 8.2 <SEP> (30.6) <SEP> 18. <SEP> 2 <SEP> 99 <SEP> 8 <September>
<tb> carbon <SEP> and <SEP> after
<tb> filtration
<tb> Cake <SEP> after <SEP> filtration <SEP> 15. <SEP> 42
<tb> 1 <SEP> issued <SEP> from <SEP> treatment <SEP> to <SEP> 8. <SEP> 0 <SEP> 56. <SEP> 4 <SEP> 4.9 <SEP> (14.1) <SEP > 9. <SEP> 2 <SEP> 93. <SEP> 9
<tb> 2%
<Tb>
** The indicated values represent the mass concentration in Ir in the medium considered Rq: values rounded to the 1 crown because of the instability of the compounds * second measurement The efficiency is of 30.8% The capacity of the black for this concentration of 3.07 mole of Ir / Kg of black 2S.

EXAMPLES 2: Recovery of Iridium on a Bottle of Distillation neither Diluted nor Hydrolyzed by 5% by Weight of Carbon Black: In a One-Liter Tetraol Equipped with Mechanical and Breathable Agitation Under Argon, are Introduced 194. 2 g of the same distillation pellet as used in Examples 1 to 3 and containing 1.2% by weight of iridium. The reaction medium is stirred and heated to 60 C.

9. 75 g of carbon black 2S (CECA) are then introduced and the temperature conditions are maintained for 1 hour. The medium is then filtered under pressure

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 of argon on stainless steel filter. The oil corresponding to the filtrate and the cake are recovered and analyzed in elemental analysis.

The results obtained are summarized in Table 2 below:
TABLE 2

<Tb>
<tb> Examples <SEP> Ir <SEP> (**) <SEP> C <SEP> H <SEP> CI <SEP> If <SEP>#
<tb> 33.1
<tb> 2 <SEP> Oil <SEP> Before <SEP> Treatment <SEP> 1. <SEP> 2 <SEP> 39. <SEP> 3 <SEP> 7. <SEP> 8 <SEP> (32.3) <SEP> 17.6 <SEP> 99. <SEP> 8
<tb> *
<tb> Oil <SEP> treatment <SEP> to <SEP> 5%
<tb> 31. <SEP> 8
<tb> mass <SEP> of <SEP> black <SEP> of <SEP> 0. <SEP> 63 <SEP> 38. <SEP> 7 <SEP> 7. <SEP> 8 <SEP> (30. <SEP> 8) <SEP> 19. <SEP> 6 <SEP> 98.5
<tb> carbon <SEP> and <SEP> after <SEP> *
<tb> filtration
<tb> Cake <SEP> after <SEP> filtration <SEP> 19. <SEP> 0
<tb> 2 <SEP> issued <SEP> from <SEP> treatment <SEP> to <SEP> 6. <SEP> 2 <SEP> 55. <SEP> 6 <SEP> 4.8 <SEP> (18.6) <SEP > 9. <SEP> 3 <SEP> 94. <SEP> 9
<tb> 5%
<Tb>
Rq: values rounded to the 10th because of the instability of the compounds * second measurement The efficiency is 47.5% The capacity of the black for this concentration of 1.243 mole of Ir / Kg of black 2S.

EXAMPLE 3 Recovery of Iridium by Carbon Black on a Diluted and Hydrolyzed Dip Base: The distillation pellet used is hydrolysed beforehand in acidic medium: In a 1-liter one-tricolor equipped with mechanical agitation, a temperature probe and a septum, the same distillation pellet as used in Examples 1 to 6 (50. 12 g) is introduced at a flow rate of 2 ml / min via a peristaltic pump on a foot of demineralized water (500 g) very strongly stirred (400 rpm). The temperature of the medium increases from 21 C to 25.3 C at the end of casting. The agitation is maintained 1:30. The whole medium is transferred to a separatory funnel and the organic phase is recovered after addition of 2x250 ml of toluene (phase A).

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A fraction of this solution is devolatilized (50 C / 70-mbar). A fluid oil of intense black color is recovered and analyzed:% Ir: 0.55% 29Si NMR: absence of SiCI ES type function (dry extract): 6. 61% 2% carbon black 2S treatment: A fraction of the toluene phase (phase A) is recovered (191. 88 g) and introduced into a monocolumn. 3. 84 g of carbon black 2S are introduced and the flask is then placed on a rotavapor at 60 ° C. and at atmospheric pressure. The carbon black is then recovered by filtration under pressure on a stainless steel filter (0.5m). The cake is washed with 150 ml of toluene and then partially dried by passing nitrogen over the cake.

The organic phase is devolatilized. The oil obtained is orange and contains 0.18% iridium. A mass of 5. 95 g of cake is recovered. It contains 1.27% of iridium.

The efficiency is 67.3% The capacity of the black for this concentration of 94. 59 10-3 mole of Ir / Kg of black 2S.

Double treatment with 5% carbon black 2S: A fraction of the toluene phase (phase A) is recovered (157. 65 g) and introduced into a monocolon. 7. 88 g of carbon black 2S are introduced and the flask is then placed on a rotavapor at 60 ° C. and at atmospheric pressure. The black is then recovered by filtration under pressure on stainless steel filter (0.5m). The cake is washed with 150 ml of toluene and then partially dried by passing nitrogen over the cake.

The organic phase is preserved. 10. 27 g of cake are recovered. It contains 0. 64% of iridium.

A second treatment is performed on the organic phase. 7. 88 g of carbon black 2S are introduced into the monocolon containing the organic phase and the medium is heated in a rotavapor for 1 hour at 60 C. The medium is then filtered.

The organic phase recovered after filtration (conditions identical to the previous ones) is devolatilized. A fluid slightly yellowish and limpid fluid is recovered. It contains 355 p.p.m. of iridium.

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The recovered carbon black is partially dried. It contains 865 p.p.m. of iridium.

The efficiency is 93.5% The capacity of the black for this concentration of 1. 892 10-2 mole of Ir / Kg of black 2S.

EXAMPLE 4 Recovery of Iridium by Carbon Black 2S (CECA) on a Diluted and Hydrolyzed Dip: The hydrolysis is carried out in a basic medium.

The raw material used is the distillation pellet identical to that of the preceding examples but in the form of a solution containing between 0. 71- 0. 72% and 0.88-0.82% of iridium and titrated with HCl (releasable ) at 0. 104 g HCI / g of solution.

The hydrolysis is done by pouring this solution on a foot of soda at room temperature so that the molar ratio: n (HCI) / n (NaOH) = 1 on a foot of demineralised water (300. 94 g) and 1N sodium hydroxide (87.24 g) is poured with vigorous stirring (470 rpm) and over 14 minutes 31. 3 g of toluene solution at room temperature. The reaction being exothermic, the temperature of the medium is regulated by an ice bath. A biphasic medium is obtained. The pH aqueous phase is between 6 and 7 (pH paper). 41. 99 g of carbon black 2S are then introduced into the medium. The medium is stirred by mechanical stirring at RT and for 2 h (no observed exotherm).

 The contents of the flask are transferred to a pressure filter (filtration on cardboard) and a toluene fraction (500 ml) which was used to rinse the contents of the flask.

 The black is then dried in an oven (55 C, under 3 mbar) for 15 hours.

 The phases are separated and analyzed.

The iridium assay leads to the following values collected in the table
3 below:

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TABLE 3

<Tb>
<tb>% <SEP> Ir <SEP> Distribution <SEP> of <SEP> Iridium
<tb> / <SEP> masses
<tb> Phase <SEP> aqueous <SEP> 29 <SEP> - <SEP> 29 <SEP> ppm <SEP>#<SEP> 5 <SEP> - <SEP> 5.5 <SEP>% <SEP> (1)
<Tb>

Huile silicone 560 p.p.m. *5-5.5%(1) Huile silicone 560 p.p.m. ;: 5 - 5.5 % (1)

Silicone oil 560 ppm * 5-5.5% (1) Silicone oil 560 ppm;: 5 - 5.5% (1)

<Tb>
<tb> Toluene <SEP><<SEP> 10 <SEP> ppm
<Tb>

Cake <SEP> 0.44 <SEP> - <SEP> 0.45 <SEP>% <SEP> 80 <SEP> -89 <SEP>% <SEP> (2) <SEP>
<Tb>
(1): inaccuracy due to bleach <100% (2): deviation due to the accuracy of the initial toluene phase assay.

The efficiency is 84.5% on average.

The capacity of the black for this concentration of 2. 94 10-2 mole of Ir / Kg of black 2S.

The percentage by weight of silicon and chlorine in the carbon black are as follows% CI: 0.64 - 0.65% Si: 0.2 - 0.3

Claims (11)

1. Process for preparing a halogenoalkyldialkylchlorosilane of formula (1):

 by hydrosilylation reaction of a reaction medium comprising a silane of formula (II):

 and an alkene halide of formula (III):

 in the presence of a catalytically effective amount of a platinum-metal-based hydrosilylation catalyst, formulas in which: - the symbol Hal represents a halogen atom selected from the atoms of chlorine, bromine and iodine, - the symbols R 2 and R 3, which are identical or different, each represent a monovalent hydrocarbon group chosen from a linear or branched alkyl radical having from 1 to 6 carbon atoms and a phenyl radical, and - s represents an integer inclusive between 2 and 10 inclusive, said process being characterized in that, finally hydrogenosilylation reaction a) the reaction medium is distilled to separate the formed product of formula (I) from a liquid distillation pellet comprising the by-products and the metal of the platinum group or its derivatives, b) the pellet formed in a) is brought into contact with an effective quantity of solid substance adsorbing the metal of the platinum group, and c) the adsorbent is separated off. platinum metal to recover said metal.  2 Process according to claim 1, characterized in that the metal of the platinum group is selected from platinum iridium, palladium, ruthenium and osmium. <Desc / Clms Page number 15>  3. Method according to claim 1 or 2, characterized in that s is equal to three and the metal of the platinum mine is iridium.  4. Method according to claim 3, characterized in that the catalyst has the formula:

 where: the symbol R4 represents an unsaturated hydrocarbon ligand comprising at least one carbon-carbon double bond and / or at least one triple bond C = C, these unsaturated bonds possibly being conjugated or non-conjugated, said ligand: being linear or cyclic (mono or polycyclic), having from 4 to 30 carbon atoms, having from 1 to 8 ethylenic and / or acetylenic unsaturations and optionally comprising one or more heteroatoms.  5. Process according to claim 4, characterized in that the catalyst is chosen from:

 (dibutyltetramethyldisiloxane) diisocyanate, di-chlorobis (-1,5-hexadiene) dichloridium, di-p-bromobis (1H-1,5-hexadiene) dichloride di-p-iodobis (1H-1,5-hexadiene) dichloridium, di- (1-chlorobis (1H-1,5-cyclooctadiene) diiridium) di-t-bromobis (1H-1,5-cyclooctadiene) diiridium, di-iodobis (1H-1,5-cyclooctadiene) dichloridium, di-p-chlorobis (1H-2,5-norbornadiene) ditridium, di-p-bromobis (r-2,5-norbornadiene) dichloride, or di-p -iodobis (rl-2,5-norbornadiene) düridium.  6. Process according to claim 4 or 5, characterized in that the calculated catalyst content by weight of metal catalyst is greater than 30 ppm calculated relative to the total weight of the reaction mixture formed by the products of formula (1), (II ) and (III). <Desc / Clms Page number 16>  7. Method according to any one of claims 1 to 6, characterized in that the method further comprises after step a), step a ') of contacting the pellet with water in the presence possibly of an organic solvent inert to HHal formed, to obtain an aqueous phase and an organic phase.  8. Process according to any one of the preceding claims, characterized in that the adsorbent is carbon black.  9. Process according to any one of claims 1 to 7, characterized in that the adsorbent is a molecular sieve, a silica, an activated alumina, or an ion exchange resin.  10. The method of claim 7 or 8, characterized in that the water is added in an amount sufficient that the HHal formed is not saturated in the aqueous phase.  11. Method according to any one of the preceding claims, characterized in that the product of formula (I) is 3chloropropyldimethylchlorosilane, the product of formula (II) is dimethylhydrochlorosilane and the product of formula (III) is the chloride of allyl