EP2097425A2

EP2097425A2 - Method for production of functionalised organo monoalkoxy (or monohydroxy) silanes in particular alkenyls

Info

Publication number: EP2097425A2
Application number: EP07822451A
Authority: EP
Inventors: Gérard Mignani; Samir Mansouri; Samuel Arthaud; Thierry Vidal
Original assignee: Rhodia Operations SAS
Current assignee: Rhodia Operations SAS
Priority date: 2006-11-10
Filing date: 2007-11-09
Publication date: 2009-09-09
Also published as: FR2908412B1; US20100140541A1; WO2008055984A3; WO2008055984A2; FR2908412A1

Abstract

The invention relates to a method for production of functionalised organo monoalkoxy (or monohydroxy) silanes in particular by alkenyls (allyls), said compounds being useful as intermediates in organic synthesis. According to the invention, dialkyldialkoxysilanes are used as starting materials and are reacted with an organic halide compound (allyl halide) (III) in an ether solvent (Sl), said compound (III) being used to substitute the alkoxy groups by functionalised groups (for example alkenyls).

Description

PROCESS FOR THE PREPARATION OF ORGANOMONOALCOXYfOU

MONOHYDROXY) FUNCTIONALIZED SILANES,

IN PARTICULAR ALCENYLES

The present invention relates to a novel route for the synthesis of functionalized, and in particular unsaturated (for example alkenyl) organomonoalkoxy (or monohydroxy) silanes, which can be used especially as synthesis intermediates in organic chemistry, for the production of organomonoalkoxy (or monohydroxy) silanes. functionalized by groups other than alkenyls, for example by amino, thiol or polysulfide groups.

The invention also provides compositions containing such synthetic intermediates in organic chemistry.

The technical problem underlying the invention is to find an alternative to the known techniques for the synthesis of functionalized organomonoalkoxy (or monohydroxy) silanes, which may allow their improvement, for example with regard to yield, productivity, cost and respect the environment.

Patent Application JP-A-2002179687 discloses a process for producing halogenated organoalkoxysilanes comprising the following steps (i) to (iii): (i) reaction of a tetralcoxysilane [Si (OCHs) ₄ ] or a trialkoxysilane with a organomagnesium compound halogen [e.g. (C 5 H ₄₎ -MgCl or (COHS) -MgCl] in solution in an ether solvent such as tetrahydrofuran (THF); this reaction takes place in a nonpolar solvent (for example xylene) and having a boiling point higher than that of the ethereal solvent containing the halogenated organomagnesium compound,

(ii) maintaining the reaction medium of step (i) at an elevated temperature of the order of 150 ^° C., optionally under reduced pressure, so as to distil the ethereal solvent (THF), the reaction between the tetraalkoxysilane or the trialkoxysilane and the halogenated organomagnesium compound continuing to obtain a reaction suspension (slurry), and

(iii) filtration of the suspension (reaction slurry) to remove the magnesium salt contained in this suspension and to recover after distillation a trialkoxysilane or a dialkoxysilane, for example of the type

(cyclopentyl) ₂ -Si (OCH ₃ ) ₂ or (cyclohexyl) ₂ -Si (OCH ₃ ) ₂ .

One of the disadvantages resulting from the use of xylene is the formation of a gel in the reaction medium, which considerably complicates the material and energy transfers. In particular, the gelled reaction medium obtained at the end of the reaction between the halogenated organomagnesium and the tetra or trialkoxysilane is not transferable from the reactor to the filter, even after dilution.

Furthermore, the magnesium salts formed in the process according to the patent application JP-A-2002179687 pose serious problems of environmental management of the effluents, in particular because of the reactivity of these salts. They react exothermically with water, releasing ethanol. In addition, these magnesium salts constitute a high pollutant load in the effluents (very high chemical demand in

Oxygen (COD)).

The application WO-A-03/027125 describes, inter alia, a process for obtaining functionalized organomonoalkoxysilanes, in particular halogens, which can be used, in particular, as synthesis intermediates. This process consists in reacting a halogenated organotrialkoxysilane with a halogenated organomagnesium compound, so as to obtain the target halogenated organomonoalkoxysilane and halogenated organomagnesium salts, according to the following reaction (Ra): (Ra)

+ 2 R ¹ OM-HaI

in which for example: • the symbol R ¹ is an ethyl group,

B is a divalent residue of formula - (CH ₂ ) S-,

The symbol HaI represents a chlorine atom,

The symbols R ² , identical or different, each represent a group -CH ₃ ,

• the symbol M represents magnesium. This synthesis can be carried out for example under conditions similar to those described in Japanese Patent No. 2-178293, namely, in particular with a halogenated organomagnesium compound in solution in an ethereal solvent and a halogenated organomagnesium compound / organotrialkoxysilane compound molar ratio. between 2: 1 and 1: 2.

The synthetic route according to the patent application JP-A-2002179687 and the application WO-A-03/027125 is a route involving a trialkoxysilane functionalized with a halogenated alkyl group and a Grignard type reaction mechanism, which involves a so-called halogenomagnetic Grignard reagent, such as MeMgCl.

It is known that one of the practical problems encountered when using an organomagnesium Grignard reagent of MeMgCl type lies in the difficulty that exists in preparing this reagent and in bringing it into the reaction medium. Indeed, the preparation of this reagent involves methyl chloride which is a gas whose handling is not easy. In addition, to introduce the reagent into the reaction medium, it is preferable that it be in the form of a solution. However, it happens that this Grignard reagent is soluble only in very few solvents, or even in a single type of solvent, in particular tetrahydrofuran (THF). In addition, the fact that the Grignard reagent is in the form of a solution in THF causes a dilution stress of the reaction medium. Finally, the dialkylalkoxy-halosilane selectivity of this synthetic route using a Grignard reagent is largely perfectible.

Naturally, these disadvantages are also found for the preparation of organomonoalkoxy (or monohydroxy) silanes functionalized with a group other than a halogen group, for example an alkenyl group.

In the latter case, the lack of selectivity of the Grignard pathway results in the production of organomonoalkoxy (or monohydroxy) silanes with low yields due to the presence of co-products such as organo-bisallylsilane. The reaction also generates annoying byproducts, namely insoluble or soluble magnesium salts which may constitute an obstacle to the separation and the collection of the targeted product.

In addition, the presence of these coproducts and these by-products of Grignard reagents (RMgX) in solution also represents a heavy constraint in environmental terms.

EP 0798302 discloses a process for the preparation of allylsilane comprising contacting magnesium metal with a mixture comprising diethylene glycol dibutyl ether, a halide (allyl chloride) and a halosilane (trimethylchlorosilane), at a temperature between 5 and 200 ⁰ C. The allylsilanes obtained are for example allyldimethylhydrogensilane, allylméthylhydrogénochlorosilane, allyltriméthylsilane, allyldiméthylchlorosilane and allylméthyldichlorosilane. It is not in any case alkoxysilanes or hydroxysilanes.

E. Larsson, Chem. Ber., 26 (1956) 39 KgI. Fysiograf. Sallskop. Lund.

Forh. describes the preparation of methylallyldiethoxysilane and methyldiallylethoxysilane

(pages 39, 40), according to a method consisting of pouring dropwise, on turnings of magnesium metal sprayed with ether, a mixture of methyltriethoxysilane and allyl chloride, keeping the whole stirring at a speed such that the reaction with magnesium continues to a temperature of about 60 ^° C. As the dropwise introduction of the mixture of methyltriethoxysilane and allyl chloride is complete, the reaction mixture is maintained for 5 hours at 70 ^° C. - 80 ⁰ C. After cooling, a precipitate is recovered and then washed with ether. The recovered ether solution is distilled to collect the targeted products. In point 4, page 40 of this document, it is described to obtain under the same conditions dimethylallylethoxysilane from dimethyldiethoxysilane and allyl chloride poured dropwise on magnesium turnings, irrespective of the molar ratio of sodium chloride. allyl / dimethyldiethoxysilane (1: 1.2: 1 or 4: 1), the maximum yields obtained with dimethylallylethoxysilane being 15, 21 and 35%. It thus appears that the selectivity of this Larsson process in monoallyldimethyl-monoalkoxysilane is relatively low and should be improved. The Larsson method is based on the well-described Barbier reaction, for example, in Handbook of Grignard, Gary S. Silverman, Philip E. Rakita, 1996, Chap. 22, p. According to this work, the Barbier reaction can be carried out by adding a haloorganic to a mixture of magnesium metal and electrophilic co-reactant such as a ketone.

One of the objectives of the present invention is to provide an alternative to the known synthesis of functionalized organomonoalkoxy (or monohydroxy) silanes, in particular alkenyl (for example dimethylethoxyallylsilane), especially useful as synthesis intermediates in organic chemistry, which may allow preferably an improvement, for example in terms of productivity, efficiency, selectivity, simplicity of implementation, cost reduction, compatibility with respect to the environment and / or availability of consumable reagents used.

Another object of the invention is to provide a process for the preparation of functionalized organomonoalkoxy (or monohydroxy) silanes, in particular alkenyl, capable of reacting with a nucleophilic agent to produce organomonoalkoxy (or monohydroxy) silanes functionalized by a different group of an alkenyl functional group, for example an amine, thiol or polysulfide functional group.

An object of the invention is also to provide novel compositions of synthesis intermediates based on functionalized organomonoalkoxy (or monohydroxy) silanes, in particular alkenyl, reduced bi-functional organomonoalkoxy (or monohydroxy) silanes.

Another object of the invention is to provide a process for the preparation of monofunctionalized organomonoalkoxy (or monohydroxy) silanes, in particular monoalkenyls, of such compounds which can constitute a new raw material opening new ways of obtaining organomonoalkoxy (or monohydroxy monofunctionalized silanes with a group other than an alkenyl functional group, for example by a group chosen from amine, thiolated or polysulphurized functional groups, in particular polysulphurized groups in which the polysulfurized entity is linked at both ends to organomonoalkoxy residues ( or monohydroxy) silanes.

An object of the present invention is also to provide a process for the preparation of functionalized organomonoalkoxy (or monohydroxy) silanes, in particular alkenylated, having a very good selectivity in monoallyl-diorganomonoalkoxy (or monohydroxy) silanes and achievable in concentrated reaction medium , so as to improve productivity and this, avoiding the use of Grignard organomagnesium reagents that pose particular security constraints, particularly during storage.

Another objective of the invention is to propose an alternative route to the "Grignard" access route to allyl-alkoxy (or monohydroxy) silanes. These objectives, among others, are achieved by the present invention which concerns first and foremost a process for preparing at least one functionalized, in particular unsaturated, for example alkenylated organomonoalkoxy (or monohydroxy) silane of formula (I):

(I) in which:

The symbol R ¹ represents hydrogen or a monovalent hydrocarbon group chosen from a linear, branched or cyclic alkyl radical having from 1 to 20 carbon atoms and a linear, branched or cyclic alkoxyalkyl radical having from 1 to 20 carbon atoms; carbon atoms;

The symbols R ² , which are identical or different, each represent a linear, branched or cyclic alkyl radical having from 1 to 8 carbon atoms; an aryl radical having 6 to 18 carbon atoms; an arylalkyl radical or an alkylaryl radical (C ₆ -C ₁₈ alkyl-C _6); R ² optionally carrying at least one halogen or perhalogenated group;

• the symbol Y represents an organic monovalent functional group, preferably selected from the functional groups "sensitive" R ³ comprising at least one ethylenic unsaturation and / or acetylenic, particularly selected from: • R ^3'1 alkenyl, linear , branched or cyclic, having from 2 to 10 carbon atoms,

Linear or branched or cyclic R ^{3 '2} alkynyl groups having from 2 to 10 carbon atoms,

• groups R ^3'3 - (alkenyl alkynyl) or - (alkynyl-alkenyl) linear, branched or cyclic, having from 5 to 20 carbon atoms, R ^3'1 radicals being particularly preferred, and Y can in optionally additionally comprise at least one heteroatom and / or carry one or more aromatic groups; -> this method being characterized o in that it consists essentially in reacting at least one organoalkoxysilane (II), selected from di-, tri-, tetra-alkoxysilanes and mixtures thereof, with at least one halogenated organic compound (III) (preferably an allyl halide), in the presence of at least one metal (M) and in the presence of at least one solvent (Sl), this halogenated organic compound (III) being capable of substituting the alkoxy radicals with organic radicals, according to the following reaction scheme (reaction II / III):

^ 1 ^M ' ^{S 1} 1 ^

(R ¹ O) -Si - (OR ¹ ) + XY (RO) -Si Y + M (X) (OR ¹ )

R ² R ²

(II) (III) (I)

or: the symbols R ¹ , R ² and Y are as defined above, the symbol M corresponds to a metal chosen from the group comprising Mg,

Na, Li, Ca, Ba, Cd, Zn, Cu, their mixtures and their alloys (preferably M is magnesium), the symbol X represents a halogen (symbol HaI), preferably a chlorine, bromine or hydrogen atom. iodine, o and in that it comprises the following steps:

-a bringing into contact with the metal M and the solvent S 1, or possibly a solvent S 2;

-b- Possible activation of the reaction, preferably by adding a catalytic amount of at least one halogen and / or an alkyl halide and / or by heating the reaction medium and / or the metal M;

addition of organoalkoxysilane (II); -d- Addition of the halogenated organic compound (III), in a progressive manner and at a rate of introduction into the reaction medium less than or equal to the rate of consumption of (III) in the reaction (II / III);

Reaction (II / III) leading to the production of the reaction product (I); the temperature of the reaction medium is preferably maintained at a temperature θr less than or equal to the boiling temperature θebS1 of the solvent S 1;

-f- Possible addition of a solvent S2;

-G- Separation and collection of a functionalized organomonoalkoxy (or monohydroxy) silane (I), preferably by distillation and, more preferably still, by distillation under reduced pressure;

-h- Possible filtration and eventual washing of the filter cake obtained, or

-h'- Possible solubilization of metal salts, preferably by washing with an acidic aqueous solution; -i- optional hydrolysis step for converting organomonoalkoxysilane (I) to organomonosilanol (I).

For the purposes of the invention, the boiling temperature "θeb" of a compound corresponds to its initial boiling point, according to the ASTM D 86-99 standard test.

One of the essential steps of the process according to the invention is the stage of progressive and controlled introduction of the halogenated organic compound (III) into the reaction medium.

Unexpectedly and after extensive research, the inventors have indeed demonstrated that the introduction of the halogenated organic compound (III), for example the allyl halide, is preferably slower than the consumption of said compound (III) in the reaction. In general, the compound (III) is in liquid form and is then called casting liquid (III) in the reaction medium. The control of this speed of introduction can be done by any appropriate means. Thus it is possible, knowing that the reaction is exothermic, to choose the temperature as a physical parameter reflecting the amount of compound (III) added to the reaction medium. An alternative, which may or may not be combined with the measurement of the reaction temperature, consists in measuring the concentration of compound (III) in the reaction medium, preferably continuously or semi-continuously, and by any appropriate and known means of the reaction medium. skilled person. It may be for example gas chromatography.

The fact of gradually introducing the compound (III) into the reaction medium makes it possible to control the exothermicity of the reaction.

According to an advantageous characteristic of the invention, during the step -d-, the halogenated organic compound (III) is introduced into the reaction medium in equivalent molar amount, or even in slight excess or slight defect, with respect to the alkoxysilane (II) starting material. By "slight" defect or excess, is meant, for example, within the meaning of the invention, a margin of ± 5 mol%.

The process according to the present invention can thus make it possible to recover the functionalized, preferably alkenyl, organomonoalkoxy (or monohydroxy) silane targeted selectively, efficiently, simply, directly, economically, industrially, without too many constraints in terms of ecotoxicity ( effluent treatment). By-products such as metal salts (for example magnesium) are formed in smaller amounts than those observed in the known routes, in particular the Grignard route. The process according to the invention is advantageously "eco-compatible". In addition, the fact of using the metal (M), preferably magnesium, in metallic form makes it possible to reduce the consumption of metal and, above all, constitutes an advantageous alternative compared to the use of a Grignard RMgX reagent in solution, delicate to prepare and store. The selectivity performance of the process of the invention is reflected in terms of yield and productivity, among others.

For similar stoichiometric conditions, the gains in yield of the compound (I) are advantageously at least 150% relative to the known Larsson technique and that the methyltrietoxysilane and the allyl chloride are added together with the mixture in the reaction medium containing the turnings of magnesium metal.

According to the process of the invention, it is possible to isolate the silane with an isolated transformation ratio of at least 65%, in particular at least 70%, or even at least 75% or even 85%, and a purity higher than or equal to 95%, and especially with a very high selectivity, especially at least 98%: for example, a single allylation occurs when Y is an allyl. In addition, the level of Si-O-Si oligomers formed is very low, for example less than 1 mol%.

This process consists, among other things, in slowly introducing the compound (III), for example the allyl halide, onto a base containing the organoalkoxysilane (II) silicone derivative and the metal (M), in particular magnesium, for example in the form of turns.

For example, the molar ratios of these reagents (III), (II) and metal (M), especially magnesium, are stoichiometric. It is also possible to use an excess of metal (especially magnesium) to further limit the formation of bis-allyl.

In the formula (I) above, the preferred radicals R ¹ are chosen from the following radicals: methyl, ethyl, n-propyl, isopropyl, n-butyl, CH 3 OCH 2 -,

CH ₃ OCH ₂ CH ₂ - and CH ₃ OCH (CH ₃ ) CH ₂ -; more preferably, the radicals R ¹ are chosen from methyl, ethyl, n-propyl and isopropyl, ethyl being particularly preferred.

The preferred radicals R ² are chosen from the following radicals: methyl, ethyl, n-propyl, isopropyl, n-butyl, n-hexyl and phenyl; more preferably, the radicals R ² are methyls.

Preferably in the functionalized organomonoalkoxy (or monohydroxy) silanes, in particular alkenyl, corresponding to formula (I), the radical Y can represent:

the symbol R representing radicals identical to or different from each other and corresponding to hydrogen or to a linear, branched or cyclic alkyl having from 1 to 8 carbon atoms, preferably -CH ₃ , -CH ₂ CH ₃ .

According to a preferred embodiment of the invention, at least one of the following definitions (preferably all the following definitions) is (are) verified in formulas (I), (II) and (III) : the symbols R ¹ and R ² , which are identical or different, each represent hydrogen,

CH ₃ CH ₂ - or CH ₃ - (preferably R ¹ represents CH ₃ CH ₂ - and R ² represents CH ₃ -); "the symbol M represents Mg;

"the symbol X represents Cl or Br;

"the symbol Y corresponds to an allyl or cyclohexene residue.

The choice of solvent S1, and optionally solvent S2, is generally an important parameter of the process according to the invention.

Thus, Sl can be chosen for example from the group of solvents having a boiling temperature θebSl lower than the boiling temperature θeb (I) of the compound

(I) -

51 may be chosen from the group of solvents having a boiling point ΘebSl generally less than 150 ^° C. (below 760 mmHg), for example less than

126 ^° C. (under 760 mmHg).

Preferably, S 1 is selected from the group of ethereal organic solvents and / or from the group of acetals, and even more preferably from the subgroup comprising tetrahydrofuran (THF), methyl-THF (Me-THF). dialkyl ethers (preferably diethyl ether or even more preferably dibutyl ether), dioxanes and mixtures thereof.

The implementation of S2 corresponds in particular to the optional step -f- and is intended to contain in solid or solubilized form any metal salts (in particular magnesium) likely to form in the reaction medium. S2 is intended to allow easier separation and collection of the object compound (I) during step -g-, namely, preferably, distillation and, more preferably still, distillation under reduced pressure. Advantageously, S2 does not react with any metal salts (for example magnesium). Preferably, S2 is different from S1.

52 is preferably chosen from the group of solvents having a boiling temperature θebS2 greater than the boiling temperature θeb (I) of the organomonoalkoxy (or monohydroxy) silane (I), and advantageously greater than the boiling temperature ΘebSl solvent S1.

It is generally appropriate that S2 is sufficiently heavy to be the last to distill with respect to the compound (I) and the solvent S 1. As solvent S2, it is possible to favor, for example, solvents chosen from the group of solvents having a boiling point θebS2 greater than 126 ^° C.

760 mm Hg), generally at least 150 ⁰ C (at 760 mm Hg), and in particular in the solvent group defined as follows: 150 ⁰ C <θebS2, preferably 180 ⁰ C <θebS2 and more preferably still, 190 ^° C. <θebS2 <350 ^° C. (below 760 mmHg).

In practice and by way of illustration, one can choose S2 in the group of solvents including hydrocarbons, hydrocarbon cuts, compounds

(poly) aromatics (especially alkylbenzenes), alkanes (especially heavy ones),

(poly) ethers, phosphorus compounds, sulfolanes (especially dialkylsulfones), ionic liquids, dialkylnitriles and mixtures thereof.

S 2 can be selected from methylal, anisole and diphenyl ether. Examples of commercial products that may be suitable as S2 solvents include petroleum fractions or hydrocarbon fractions, in particular those sold under the name ISOPAR ^® M, N or P, by Exxon Mobil Chemical, or else alkylbenzene.

According to a variant of the invention, the possible addition of S2 in the reaction medium, at the beginning of the process, for example with Sl, in particular during step -a-, and / or during step -f - optional, is advantageously associated not only with a step -g- separation and collection of a functionalized organomonoalkoxy (or monohydroxy) silane (I), preferably by distillation and, more preferably still, by distillation under reduced pressure, but also with the optional step -h'- which intervenes, advantageously, after the step -g- and which consists in solubilizing the metal salts (for example magnesium) present in solid form (for example in suspension) in the reaction medium, this solubilization is preferably carried out by adding an aqueous acidic solution. The metal salts (for example magnesian) thus solubilized form by-products relatively easy to manage on the environmental level.

It is conceivable, in accordance with the invention, that the possible addition of S2 takes place not only during step -a- and / or during the possible step -f-, but also at any time of the process. preferably before and / or during step -g-, at least once. In a quantitative sense, in general, the solvent S1 is employed such that the SI / M molar ratio is between 3: 1 and 1: 1, preferably between 2.5: 1 and 1.5: 1, and, more preferably, about 2: 1.

The amount of the solvent S 2 used in the reaction medium may for example be between 50 and 300 g per 300 g of reaction medium before the step -h- separation and collection of the compound (I).

One of the preferred characteristics of the process according to the invention concerns the control of the temperature of the reaction medium θr. Generally speaking, θr can depend on operating conditions of the process, in particular the type of casting of the halogenated organic compound (III).

The temperature θr can be for example between approximately (θebSl - (θebS1 x 0.50)) and ΘebS1, in particular between approximately (ΘebS1 - (ΘebS1 x 0.20)) and ΘebS1. Examples of temperature ranges for θr according to the nature of the solvent S 1 are given below: ______________________________________ Ethyl ether: 30 ⁰ C <θr <40 ⁰ C o THF: 30 ⁰ C <θr <65 ⁰ C Dibutyl ether 100 ⁰ C <θr <140 ⁰ C According to a preferred embodiment, the halogenated organic compound (III) is a haloalkenyl, preferably a halide (especially chloride or bromide) of allyl or methallyl isopenyl, butenyl or hexenyl cyclic or not, and, more preferably still, an allyl chloride or bromide.

According to a particularly advantageous characteristic of the invention, the step -h- separation and collection of the compound (I) is carried out discontinuously in at least one time, preferably by distillation under reduced pressure.

In order to perfect the performance of the process of the invention, particularly with regard to the selectivity, it is advantageous to use an M / (II) molar ratio of between 1.4: 1 and 1: 1, preferably between 1 , 3: 1 and 1.1: 1, and even more preferably equal to about 1.2: 1.

Below is a description of the possibilities of implementing steps -a -i. In practice, the reaction pressure is, for example, ambient atmospheric pressure.

Advantageously, the bringing together of the metal M, for example magnesium, with the solvent S1, for example the anhydrous ether, may consist of disposing of metal turnings, chips or the like in a reactor and then adding the solvent S1, or possibly a solvent S2, in the latter.

Step -b This optional activation may be catalytic type chemical, by adding a catalytic amount of at least one halogen and / or an alkyl halide. For example, the halogen (X ') optionally introduced is a grain or an iodine crystal with or without a solvent of the type 1, 2-dibromoethane or any other haloalkane.

This catalytic type chemical activation can be supplemented or replaced by a thermal activation of the metal M, which consists, for example, in simply leaving said metal M for several minutes at an activation temperature close to the temperature of the reaction medium θr.

An indicator of the end of the activation period may advantageously be the discoloration of the reaction medium. Step -c-

The organoalkoxysilane (II) is added to the reaction medium without particular precautions.

Alternatively, the organoalkoxysilane (II), for example dialkoxydialkylsilane wherein R1 is methyl and R2 is methyl, may be added prior to the introduction of the halogen X '.

Step -d- The halogenated organic compound (III), preferably the allyl halide, is slowly introduced into the reaction medium, which is maintained at a temperature θr, corresponding for example to about 80% of the boiling point. θebSl of the solvent Sl. In practice, this can be for example about 30 ⁰ C when S1 is diethyl ether and about 50 ⁰ C when S1 is tetrahydrofuran. Step

The reaction (II / III) can take place for several hours at a temperature θr, for example for 1 to 36 hours, preferably for 1 to 24 hours.

Since the reaction is exothermic, the temperature of the reaction medium is controlled by the rate of introduction of the halogenated organic compound (III) as well as by any known and appropriate temperature maintenance means (for example by the use of a refrigerant reaction chamber).

Step -f-

The optional addition of solvent S2 is carried out conventionally without any particular precaution. In general, the amount of solvent S2 used is such that the reaction medium can be easily stirred and / or transferred from one place to another.

Step -g-

Distillation is one of the appropriate methods among others for selectively isolating the organomonoalkoxy (or mono) silane (I) from the reaction medium. For this purpose, it is important that θebS2 be greater than θeb (I) in the case where S2 is used. In practice, this distillation can be carried out at a temperature between

40 and 120 ⁰ C, preferably between 70 and 90 ⁰ C, under a reduced pressure of between 1 and 50 millibars, preferably between 10 and 30 millibars.

Step -h-

In particular, in the case where a precipitate or an insoluble reaction mass is formed in the reaction medium, it is generally appropriate to then carry out a filtration of the reaction medium and then optionally a washing of the filtration cake obtained, according to conventional techniques.

For example, the filter used may be a glass frit, a wire mesh filter, etc. The solvent used for washing the cake is advantageously Sl and / or S2.

Step -h'-

This optional step of solubilizing metal salts (for example magnesium) is an alternative to the step -h-. The -h'- step, just like the -h- step, preferably occurs after a distillation -g- of the target functionalized organomonoalkoxy (or monohydroxy) silane (I). It is preferably carried out using an acidic aqueous solution, for example based on at least one strong acid (especially mineral acid), such as HCl, in particular so as to bring the pH of the reaction medium to a pH that is advantageously equal to at about 4.0-4.5.

Step -i-

This optional hydrolysis step is preferably carried out by rapid or gradual addition of a hydrolysis agent, preferably water, or, alternatively, a solution, in particular a hydroorganic solution, for example buffered with a pH of between 4.5 and 8 and according to a stoichiometry such that there is 1 to 2 equivalents (for example 1.5 equivalents) of water per equivalent of organomonoalkoxy (or mono) silane (I).

According to a preferred embodiment of the invention, the hydrolysis temperature is between 40 and 90 ^° C., in particular between 50 and 90 ^° C., for example between 70 and 80 ^° C.

Advantageously, in the process according to the invention, the metal salts

(optionally halogenated) which are formed at the end of the reaction have the significant advantage of being insoluble in the reaction medium, so that they can be separated easily and efficiently from it, without constituting an excessive pollutant load (low COD).

In the -h'- variant, the removal of the metal salts is even easier, these being in the form of an aqueous solution.

One of the essential points of the process of the invention is to propose a slow introduction of the compound (III) into the reaction medium, so that the latter always has a low or even zero concentration of Grignard reagent as well as in compound (III) (in particular allyl halide).

Another important element of said process lies in the moment of introduction of the compound (III), which is subsequent to the incorporation into the reaction medium of the compound (II), the solid metal M, the solvent S1 and any halogen X '(or any alkyl halide).

According to the invention, the reaction medium does not advantageously comprise solid Grignard reagent and therefore does not carry the constraints related to the Grignard type reaction mechanism (in particular the storage problem). The process according to the invention may comprise continuous sequences, but it is preferably semi-continuous.

According to the invention, the product (I) obtained at the end of the process described above is a synthesis intermediate, in particular capable of reacting with at least one nucleophilic agent for the production of other organoalkoxysilanes functionalized with groups Y other than R ³ groups, in particular by groups other than alkenyls, for example by amino, thiol or polysulfide functional groups.

The nucleophilic agent with which the synthesis intermediate (I) is capable of reacting for the production of these organoalkoxysilanes functionalized with groups Y other than the groups R ³ can be of different natures. In particular, it may be a nucleophilic agent of the type of those described in the application WO-A-03/027125 (page

12, line 10 to page 14, line 27).

For more details on the practical implementation of the aforementioned synthesis, reference may be made to the content of the patent application EP-A-0848006, which illustrates, with other reagents, procedures applicable to the conduct of the synthesis considered.

The present invention also relates to a composition (synthetic intermediates composition) comprising: an effective amount of at least one organomonoalkoxy (or monohydroxy) silane of formula (I) (directly) obtained by the process according to the invention:

(I) R ¹ , R ² and Y being as defined above; at most 5%, preferably at most 1% and more preferably at most 0.5%, by weight of:

R ²

Y-Si - Y

(I)

R ² and Y being as defined above. Preferably, in this composition, the symbols R ¹ and R ² , which are identical or different, each represent CH ₃ CH ₂ - or CH ₃ - (more preferably, R ¹ represents CH ₃ CH ₂ - and R ² represents CH ₃ -) and the symbol Y represents a group R ³ , more preferred is an alkenyl group and, more preferably still, an allyl or methallyl group.

The following examples illustrate the invention without, however, limiting its scope.

EXAMPLES

Example 1

In a 100 ml three-necked reactor, 1.00 g (41.1 mmol) of Mg in turnings, 20 ml of anhydrous ether and 0.2 ml (2.3 mmol) of 1,2-dibromoethane are introduced under argon. . A solution of 5.00 g (40.96 mmol) of allyl bromide in 20 ml of anhydrous ether is slowly introduced over 2 hours. The temperature is maintained at 40 ^° C. There is disappearance of Mg and allyl bromide. In a second reactor, 20 ml of anhydrous ether and 6.30 g (41.25 mmol) of dimethyldiethoxysilane are introduced under nitrogen. The solution of the first reactor is then slowly introduced. The temperature is maintained at 30-35 ^° C. There is formation of a white precipitate. It is allowed to react for 72 hours. It is then filtered under nitrogen and the filter cake is washed with anhydrous ether. The ether solution is evaporated. A liquid is obtained which contains exclusively allyldimethylethoxysilane. The yield isolated by distillation is approximately 40% (boiling point: 126 ^° C. at 760 mmHg). The amount of bisallyldimethylsilane is less than 1 mol%. The NMR, IR, Raman and SP mass analyzes confirm the following structure of the product obtained:

Example 2

In a 100 ml reactor under argon, 11 ml of anhydrous THF, 2.034 g (82.88 mmol) of Mg in turns, an iodine grain and 6.30 g (41.25 mmol) of dimethyldiethoxysilane are introduced. 4.020 g (54.42 mmol) of allyl chloride are then introduced slowly. Allowed to react for 6 hours at room temperature. The degree of conversion of dimethyldiethoxysilane is complete. 10 ml of diisopropylbenzene (mixture of isomers) are then added. The reaction mass is then directly distilled. Allyldimethylethoxysilane is obtained with a yield of 72%. The amount of bisallyldimethylsilane is less than 1 mol%. Example 3

In a 100 ml reactor under argon, 18 ml of anhydrous ether, 2.25 g (92.46 mmol) of Mg in turnings and one grain of iodine are introduced. 12.60 g (82.44 mmol) of dimethyldiethoxysilane are then added and 8.22 g (107.12 mmol) of allyl chloride are slowly run in. It is left to react for 21 hours at room temperature. 60 ml of Isopar M. are then added. The mixture is filtered under nitrogen and, by distillation of the reaction mass, 8.50 g of allyldimethylethoxysilane are recovered in a yield of 73%. The amount of bisallyldimethylsilane is less than 1 mol%.

Example 4

In a three-necked 100 ml under argon, 3.65 g (150 mmol) of Mg in turnings, 15 ml of anhydrous ether, an iodine crystal and 100 μl of 1,2-dibromoethane are introduced. 5.49 g (36 mmol) of dimethyldiethoxysilane are then introduced and then a solution of 3.63 g (29.7 mmol) of allyl bromide in 18 ml of anhydrous ether is slowly poured. The reaction is maintained at 39-40 ^° C. for 18 hours. Cooled to room temperature. 20 ml of ethanol are added to the reaction mass. After filtration, it is distilled under vacuum. Thus, pure allyldimethylethoxysilane is recovered.

EXAMPLE 5 1.04 g (42.7 mmol) of Mg in turnings and 8 ml of anhydrous ether are introduced into a 100 ml three-necked flask under argon. 4.4 ml of dichlorodimethylsilane (36.2 mmol) and one iodine grain are then introduced. 3.9 ml (47.4 mmol) of allyl chloride are then added. The reaction is exothermic. The temperature is maintained at 40 ^° C. for 40 minutes. Then it is maintained 24 hours at room temperature. The reaction mass is treated with 20 ml of ethanol and 20 ml of triethylamine. The reaction mass is filtered. The filtrate is then taken up in 50 ml of ether. The organic phase is washed with a saturated solution of NH ₄ Cl, dried and distilled under vacuum. Allyldimethylethoxysilane is thus obtained with a yield of approximately 50%. The amount of bisallyldimethylsilane is about 20 mol%.

Example 6

In a three-necked 1 liter argon was charged with 51.9 g (2.13 mol) of Mg in turn, 300 ml of anhydrous ether. 126 ml (0.71 mol) of dimethyldiethoxysilane are then introduced. 500 μl of 1,2-dibromoethane and an iodine crystal are then charged. With the aid of a dropping funnel, 86 ml (1.04 mol) of allyl chloride are slowly introduced. The reaction is exothermic and the temperature of the reaction mass is maintained at 35-40 ^° C. during casting. It is left for 2 hours at room temperature. Then the reaction mass is then filtered and the cake washed with 3 times 100 ml of anhydrous ether. The filtrate is then distilled under vacuum. 82.6 g is obtained of allyldimethylethoxysilane, with a yield of 76%. The amount of bisallydimethylsilane is less than 1 mol%.

EXAMPLE 7 In a strictly anhydrous 250 ml three-necked flask, with temperature probe, magnetic stirrer, oil bath, refrigerated and under argon, 2.47 g of Mg in turns (1.2 eq.), 80 ml of diethylene glycol are introduced. dry dibutyl ether, 1 grain of iodine. The Mg is allowed to activate for 20 minutes at 100 ^° C. Once the reaction mass is decolorized, and still at 100 ^° C., 400 μl of dibromoethane is introduced until a cloud in the reaction mass appears. 14.6 ml of diethoxydimethylsilane are then introduced. 13.4 ml of allyl chloride (2.0 eq.) Are then slowly poured, while maintaining the temperature of the reaction mass at 110 ^° C. After distillation, the isolated yield of allyldimethylethoxysilane is approximately 55% without formation of bisallydimethylsilane.

Example 8

In a tricolor of 250 ml strictly anhydrous, with temperature probe, magnetic stirring, oil bath, refrigerate and under argon, 2.47 g of Mg in turns (1.2 eq.), 80 ml of anisole are introduced. dry and 1 grain of iodine. The Mg is allowed to activate for 20 minutes at 100 ^° C. Once the reaction mass is decolorized, and still at 100 ^° C., 150 μl of dibromoethane are introduced until a cloud in the reaction mass appears. 14.6 ml of diethoxydimethylsilane are then introduced. Then gently poured 12.2 ml of allyl chloride (1.8 eq.), Maintaining the temperature of the reaction mass at 110 ^° C. After distillation, the isolated yield of allyldimethylethoxysilane is about 65%, without formation of bisallydimethylsilane.

Example 9

In a three-neck of 2 liters strictly anhydrous, with temperature probe, magnetic stirrer, oil bath, refrigerant and under argon, 36.98 g of Mg in turns (1.3 eq), 1.2 liters of dibutyl are introduced. dry ether and 250 mg of iodine. The Mg is allowed to activate for 45 minutes at 115 ^° C. After the reaction mass has been decolorized, and still at 115 ^° C., 3 ml of dibromoethane are introduced until a cloud in the reaction mass appears. 219 ml of diethoxydimethylsilane are then introduced. 163 ml of allyl chloride (1.6 eq.) Are then gently poured in (10 ml / h) while maintaining the temperature of the reaction mass at 115 ^° C. A conversion rate of greater than 95% is obtained after 24 hours. reaction. The reaction mass is then distilled at 760 mm Hg using a 30 cm packed column with retrogradation and a 1/10 reflux ratio. After distillation, the isolated yield of allyldimethylethoxysilane is about 71%, without formation of bisallydimethylsilane. Example 10

In a 1-liter, nitrogen-inert, double-jacketed reactor with temperature probe and mechanical stirring, 35 g of Mg in turnings (1.53 eq), 198.5 g of anhydrous dibutyl ether and 70 mg are introduced. diode. The Mg is allowed to activate at 130 ^° C. After the reaction mass has been decolorized, and still at 130 ^° C., 140 g of diethoxydimethylsilane are introduced. Then gently poured 88 g of allyl chloride (1.22 eq.) Diluted in 212 g of anhydrous dibutyl ether (duration of about 5.5 hours). The reaction medium is maintained at 130 ^° C. for 16 hours; a transformation rate of greater than 95% is obtained. The reaction mass is then distilled under reduced pressure (minimum pressure: 350 mbar), using a packed column of 60 cm, with retrogradation and a reflux ratio of 1/10. After distillation, the isolated yield of allyldimethylethoxysilane is 79%, without formation of bisallydimethylsilane.

It is loaded in a 100 ml monocolon:

2.0 g (13 mmol, 1 eq) of allylethoxydimethylsilane,

20 ml of CH ₃ CN, 20 ml of 2M acetic acid (4 mmol, 3.1 eq).

Stirred at room temperature for 26 hours.

Extracted with twice 40 ml of diethyl ether and the organic phases are combined.

The organic phase thus obtained is washed with 7 times 30 ml of water. The organic phase is dried over MgSO ₄ .

It is filtered on frit # 4.

The filtrate is evaporated on a rotary evaporator (30 ^° C., pressure of 25 mbar). A clear, mobile yellow liquid with a mass of 1.37 g is obtained with a yield of 91%. The structural analysis indicates that the liquid obtained contains mainly the product of following structure:

Claims

Process for preparing at least one functionalized organomonoalkoxy (or monohydroxy) silane, of formula (I):

(I) in which:

The symbol R ¹ represents hydrogen or a monovalent hydrocarbon group chosen from a linear, branched or cyclic alkyl radical having from 1 to 20 carbon atoms and a linear or branched linear alkoxyalkyl radical having from 1 to 20 atoms of carbon ;

The symbols R ² , which are identical or different, each represent a linear, branched or cyclic alkyl radical having from 1 to 8 carbon atoms; an aryl radical having 6 to 18 carbon atoms; an arylalkyl radical or an alkylaryl radical (aryl

C ₆ -C ₁₈ alkyl-C _6); R ² optionally carrying at least one halogen or perhalogenated group;

The symbol Y represents an organic monovalent functional group, preferably chosen from functional groups R, comprising at least one ethylenic and / or acetylenic unsaturation, in particular selected from:

• R ^3'1 alkenyl groups, linear, branched or cyclic, having from 2 to 10 carbon atoms,

• R ^3'2 alkynyl groups, linear, branched or cyclic, having from 2 to 10 carbon atoms, • R ^3'3 - (alkenyl alkynyl) or - (alkynyl-alkenyl) linear, branched or cyclic having 5 to 20 carbon atoms, R ^3'1 radicals being preferred, and Y may optionally further comprise at least one heteroatom and / or be provided with one or more aromatic groups; -> this method being characterized o in that it consists essentially in reacting at least one organoalkoxysilane (II) selected from di-, tri-, tetra-alkoxysilanes and mixtures thereof with at least one halogenated organic compound (III ) (preferably an allyl halide), in the presence of at least one metal (M) and in the presence of at least one solvent (Sl), this halogenated organic compound (III) being capable of substituting the alkoxy radicals with organic radicals, according to the following reaction scheme (reaction II / III):

^R2 M, if ^

(R ¹ O) -Si - (OR ¹ ) + XY (RO) -Si Y + M (X) (OR ¹ )

R ² R ²

(II) (III) (I)

Na, Li, Ca, Ba, Cd, Zn, Cu, their mixtures and their alloys, preferably M being magnesium, the symbol X represents a halogen, preferably a chlorine, bromine or iodine atom, and in that it comprises the following steps:

-f- Possible addition of a solvent S2;

-h- Possible filtration and eventual washing of the filter cake, or

-h'- Possible solubilization of metal salts, preferably by washing with an acidic aqueous solution; -i- optional hydrolysis step for converting organomonoalkoxysilane (I) to organomonohydroxysilane (I).

2. Method according to claim 1, characterized in that:

the radicals R ¹ are chosen from the following radicals: methyl, ethyl, n-propyl, isopropyl, n-butyl, CH ₃ OCH ₂ -, CH ₃ OCH ₂ CH ₂ - and CH ₃ OCH (CH ₃ ) CH ₂ - ,

the radicals R ² are chosen from the following radicals: methyl, ethyl, n-propyl, isopropyl, n-butyl, n-hexyl and phenyl,

the radical Y represents:

the symbol R representing radicals which are identical to or different from one another and correspond to hydrogen or a linear, branched or cyclic alkyl having from 1 to 8 carbon atoms, preferably -CH ₃ or -CH ₂ CH ₃ .

3. Method according to one of claims 1 and 2, characterized in that, during step -d-, the halogenated organic compound (III) is introduced into the reaction medium in equivalent molar amount relative to the alkoxysilane (II).

4. Method according to one of claims 1 to 3, characterized in that Sl is selected from the group of solvents having a boiling temperature θebSl below the boiling temperature θeb (I) of the compound (I).

5. Method according to one of claims 1 to 4, characterized in that Sl is a solvent having a boiling temperature ΘebSl less than 150 ⁰ C (under 760 mmHg).

6. Method according to one of claims 1 to 5, characterized in that Sl is chosen from the group of ethereal organic solvents and / or from the group of acetals, and more preferably still, from the subgroup comprising tetrahydrofuran. (THF), methyl-THF (Me-THF), dialkyl ethers (preferably diethyl ether or dibutyl ether), dioxanes and mixtures thereof.

7. Method according to one of claims 1 to 6, characterized in that S2 is selected from the group of solvents having a boiling temperature θebS2 greater than the boiling temperature θeb (I) of the compound (I) and, advantageously, greater than the boiling temperature θebSl of the solvent S1.

8. Method according to one of claims 1 to 7, characterized in that S2 is a solvent having a boiling temperature θebS2 greater than 126 ⁰ C (below 760 mmHg), in particular at least 150 ⁰ C (at 760 mmHg), in particular chosen from the group of solvents defined as follows: 150 ^° C. <θebS2, preferably 180 ^° C. <θebS2 and, more preferably still, 190 ^° C. <θebS2 <350 ^° C. ( under 760 mmHg).

9. Method according to one of claims 1 to 8, characterized in that S2 is selected from the group of solvents including hydrocarbons, hydrocarbon cuts, (poly) aromatic compounds (especially alkylbenzenes), alkanes ( particularly heavy), (poly) ethers, phosphorus compounds, sulfolanes (especially dialkylsulfones), ionic liquids, dialkylnitriles and mixtures thereof.

10. Method according to one of claims 1 to 9, characterized in that the temperature θr is between about (ΘebSl - (ΘebSl x 0.50)) and ΘebSl, in particular between about (ΘebSl - (ΘebSl x 0.50 )) and ΘebSl.

11. Method according to one of claims 1 to 10, characterized in that Sl comprises: o diethyl ether with 30 ⁰ C <θr <40 ⁰ C, o THF with 30 ⁰ C <θr <65 ⁰ C, dibutyl ether with 100 ^° C. <θr <140 ^° C.

12. Method according to one of claims 1 to 11, characterized in that the step of -g- separation and collection of (I) is performed discontinuously in at least one time, preferably by distillation under reduced pressure .

13. Method according to one of claims 1 to 12, characterized in that the halogenated organic compound (III) is a haloalkenyl, preferably a halide (chloride or bromide) of allyl or methallyl, isopenyl, butenyl or cyclic or non-cyclic hexenyl, and more preferably still an allyl chloride or bromide.

14. Method according to one of claims 1 to 13, characterized in that the molar ratio SI / M is between 3: 1 and 1: 1, preferably between 2.5: 1 and 1.5: 1 and more preferably still equal to about 2: 1.

15. Method according to one of claims 1 to 14, characterized in that the molar ratio M / (II) is between 1.4: 1 and 1: 1, preferably between 1.3: 1 and 1, 1: 1 and, more preferably still, equal to about 1.2: 1.

16. Composition comprising: an effective amount of at least one organomonoalkoxy (or monohydroxy) silane of formula (I) directly obtained by the method according to one of claims 1 to 15:

(I)

and at most 5%, preferably at most 1% and, more preferably still, at most 0.5% by weight of:

R ²

Y-Si - Y

R ² R> 2 and Y being as defined in one of claims 1 to 15.

17. Composition according to claim 16, characterized in that the symbols R ¹ and R ² , which are identical or different, each represent CH ₃ CH ₂ - or CH ₃ -, preferably R ¹ representing CH ₃ CH ₂ - and R ² representing CH ₃ -, and the symbol Y represents a group R3, preferably an alkenyl group and, more preferably still, an allyl or methallyl group.