WO2009003955A1

WO2009003955A1 - Process for preparing hydrazo-silane compounds using an alkoxylated hydrazocarboxylate precursor

Info

Publication number: WO2009003955A1
Application number: PCT/EP2008/058307
Authority: WO
Inventors: Thierry Vidal; Virginie Pevere
Original assignee: Rhodia Operations
Priority date: 2007-06-29
Filing date: 2008-06-27
Publication date: 2009-01-08
Also published as: FR2918062A1; FR2918062B1

Abstract

The present invention relates to a process for preparing intermediate hydrazo-silane compounds (precursors of azo-silane compounds), in which: - a precursor H-X1-Z is prepared and/or used, - an alkoxylated hydrazodicarboxylate precursor is prepared and/or used, - the precursor H-X1-Z is reacted with the alkoxylated hydrazodicarboxylate precursor, in the presence of a solvent S, preferably tetrahydrofuran (THF), - the solvent S is eliminated, preferably by distillation, - and the hydrazo-silane compound is recovered, preferably by change to the solid state, then filtration.

Description

PROCESS FOR THE PREPARATION OF HYDRAZO-SILANE S COMPOUNDS

IMPLEMENTING A PRECURSOR

HYDRAZOCARBOXYLATE ALCOXYL

The field of the invention is that of the synthesis of functionalized hydrazo-silane intermediates, precursors of functionalized azosilane compounds. The hydrazo-silane compounds more particularly concerned by the invention are those comprising at least one activated hydrazo group. This activation may result, for example, from the presence of neighboring carbonyl groups of the nitrogens. The silane part of these compounds may comprise, in particular, hydrolysable or condensable groups of the ≡SiOR or ≡SiOH type.

Such hydrazo-silane compounds are oxidatively transformable intermediates to azo-silane compounds with activated azo group (s) (such as those with -CO- N = N-CO- group). These latter compounds are very useful, especially in the synthesis of active organic molecules (in particular nitrogenous heterocycles) that can be used in the fields of agrochemistry and pharmacy, for example as dienophiles in reaction with hetero-Diels Aider. They may also be useful as white-elastomeric coupling agents in elastomer compositions comprising a white filler, especially a siliceous material (such as precipitated silica), as a reinforcing filler.

However, few of these compounds are accessible, particularly because of their difficult preparation. It would therefore be desirable to remedy this by increasing the number of access routes to these azosilane compounds and therefore the synthesis routes of the hydrazino-silane precursors. The patent application FR-A-2340323 discloses azosilane compounds of formula (I *):

YX-CO-N = N-CO-X ¹ -Z * wherein X and X ¹ are the same or different and each represents an imino group, an oxygen atom or a substituted or unsubstituted methylene group; Y is an alkyl, aryl or aralkyl group, substituted or unsubstituted, or is the same as Z *; Z * is an alkyl, aryl or aralkyl group which has as substituent at least one silane group of formula Si (OR) ₃ or OSi (OR) ₃ in which R is a straight or branched chain alkyl group, preferably with 1 to 6 carbon atoms. In particular, this application mentions azo-silane compounds of formula (II *) and (III *): (II *): R ^{1 *} -O-CO-N = N-CO-NH- (C ₆ H 4) - (CH ₂ ) _m -Si (OR ^{2 *} ) 3 (IIP): R ^{1 *} -O-CO-N = N-CO-NH- (CH ₂ ) _n -Si (OR ^{2 *} ) ₃ in which R ^{1 *} and R ^{2 *} are the same or different and each represents a straight or branched chain alkyl group, preferably containing 1 to 6 carbon atoms, m is 0, 1, 2 or 3 and n is equal to 1, 2 or 3.

An azosilane compound of formula Ethyl-O-CO-N = N-CO-NH- (CH ₂ ) ₃ -Si (Ethyl) ₃ , according to formula (III *), is disclosed in Example 3.

The key step in the synthesis of this type of azo-silane compounds with an activated azo group is the oxidation of a hydrazo (NH-NH) type function of the precursor, as a function azo (N = N) corresponding to using an oxidizing system comprising an oxidant formed by a halogen derivative (chlorine, bromine, N-bromosuccinimide for example) and a pyridine-type base.

According to the patent application FR-A-2340323, the hydrazo precursors of azosilane compounds with an activated azo group are obtained by reaction of a substituted carbazate with a substituted isocyanate. Thus, the hydrazo precursors of the azosilane compounds of formula (II *) are prepared by condensing an alkyl carbazate (R ¹ *) with a p-isocyanato-aryl or a p-isocyanato-aralkyl-trialkoxy (R ^{2 *} ) silane; and the hydrazo precursors of the azosilane compounds of formula (III *) are prepared by condensing an alkyl carbazate (R ¹ *) with an isocyanato-alkyl-trialkoxy (R ^{2 *} ) silane. Isocyanatopropyltrialkoxysilane is obtained by using, as raw materials, aminopropyltrialkoxysilane and alkyl chloroformate (for example ethyl) or aryl (for example phenyl). This known synthesis of hydrazo-silane intermediates is perfectible especially in terms of yield, selectivity and cost.

In this context, one of the essential objectives of the present invention is to provide a process for the preparation of at least one hydrazo-silane compound of formula (I) as defined in claim 1, which can be converted into an azo compound -Silane, by oxidation of the hydrazo group, this method providing an alternative way of access to a key intermediate, which can improve the efficiency, productivity and / or economy of the process.

This objective, among others, is achieved by the invention which concerns, first of all, a process for preparing at least one hydrazinosilane compound of formula (I):

Y - X - CO - NH - NH - CO - X ¹ - Z (I) in which:

→ X is an amino group -NR °, with R ° representing a hydrogen atom (H), a linear, branched or cyclic alkyl group having from 1 to 20 carbon atoms, a group aryl having 6 to 18 carbon atoms, or an aralkyl group (C ₆ -C ₁₈ aryl, C ₁ -C ₂₀ alkyl), said alkyl, aryl or aralkyl group being substituted or unsubstituted, an oxygen atom, a sulfur atom, a covalent bond or a linear, branched or cyclic alkylene group having from 1 to 20 carbon atoms, substituted or unsubstituted;

→ X ¹ is an amino group -NR °, with R ° representing a hydrogen atom (H), a linear, branched or cyclic alkyl group having from 1 to 20 carbon atoms, an aryl group having from 6 to 18 carbon atoms, or an aralkyl group (C ₆ -C ₁₈ aryl, C ₁ -C ₂₀ alkyl), this alkyl, aryl or aralkyl group being substituted or unsubstituted, an oxygen atom, a sulfur atom or a linear, branched or cyclic alkylene group having from 1 to 20 carbon atoms, substituted or unsubstituted;

Y is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 18 carbon atoms or an aralkyl group

(C ₆ -C ₁₈ aryl, C ₁ -C ₂₀ alkyl), this alkyl, aryl or aralkyl group being substituted or unsubstituted or being the same as Z and optionally carrying at least one heteroatom (for example O, N or S; Y may thus contain, for example, ether groups, such as those included in residues (poly) alkylene (for example ethylene) glycol); and

-> Z is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 18 carbon atoms or an aralkyl group (C ₆ -C ₁₈ aryl), C ₁ alkyl -C ₂₀ ), this alkyl, aryl or aralkyl group being substituted with at least one polyorganosiloxane group and / or at least one silane group, this (s) substituent group (s) (polyorganosiloxane and / or silane) responding to the formula: - SiR ¹ _a (OR ² ) _b (OSiR ³ R ⁴ R ⁵ ) _c wherein: → a, b, c are integers chosen such that a + b + c = 3; -> R ¹ , R ² , R ³ , R ⁴ and R ⁵ are independently of each other an alkyl group, linear, branched or cyclic, having from 1 to 20 carbon atoms, an aryl group having from 6 to 18 atoms carbon, or aralkyl (C ₆ -C ₁₈₎ aryl, C _1-6 alkyl, C ₂₀ ), said alkyl, aryl or aralkyl group being substituted or unsubstituted and optionally carrying at least one heteroatom;

characterized in that it consists essentially of: 1. preparing and / or implementing an H - X ¹ - Z precursor; with X ¹ and Z as defined above;

2. preparing and / or implementing an alkoxylated hydrazodicarboxylate precursor of formula (II):

Y - X - CO - NH - NH - CO - W (II) in which:

W is a halogen or OR ⁶ , R ⁶ being a hydrogen atom (H), a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 18 atoms carbon, or aralkyl (C ₆ -C ₁₈ aryl, C ₁ -C ₂₀ alkyl) group, wherein said alkyl, aryl or aralkyl group is substituted or unsubstituted, and Y, X are as defined above; and

3. reacting said precursor H - X ¹ - Z with said alkoxylated hydrazodicarboxylate precursor of formula (II).

When a (respectively b) is equal to 2 or 3, then the 2 or 3 corresponding groups R ¹ (respectively R ² ) may be different or, in general, identical to each other.

In the present disclosure, compounds (or intermediates) hydrazo-silanes of formula (I) are understood to mean the compounds of formula (I) above for which the (or each) substituent group of group Z is a polyorganosiloxane group or a silane group, corresponding to the formula - SiR ¹ _a (OR ² ) _b (OSiR ³ R ⁴ R ⁵ ) _c above.

This new route of synthesis of hydrazo-silane intermediates of formula (I) is easy to implement and makes it possible to achieve a satisfactory yield and selectivity, while remaining economically viable. In this respect, this alternative of synthesis can make it possible to limit the consumption of silane reagent, with respect to the known synthetic route mentioned above.

The precursor H - X ¹ - Z makes it possible to have a large diversity of reagents beyond the amines, namely in particular thiols and alcohols.

If the order of steps 1 and 2 can be arbitrary (for example 1 before 2, 2 before 1, 1 and 2 simultaneously), step 1 is preferably performed before step 2. At the end of step 3, it is possible according to one variant of the invention to recover the hydrazo-silane compound of formula (I), by any appropriate means. Such a recovery can be done by isolating or not the final reaction medium hydrazo-silane compound of formula (I). According to one particular embodiment, the hydrazo-silane compound of formula (I) targeted is recovered by passage in the solid state (the compound of formula (I) is, for example, crystallized), and then filtration.

The reaction of step 3 is for example a condensation reaction.

Preferably, W is a halogen, preferably a chlorine atom.

The reaction of the H-X ¹ -Z precursor with the alkoxylated hydrazodicarboxylate precursor of formula (II) results in the formation of a HW coproduct. It is advantageous, according to the present invention, for this HW acid formed to be neutralized. Also it is preferable that the reaction medium comprises at least one base intended to react with the acid HW formed at the end of the reaction of the precursor H - X ¹ - Z with the alkoxylated hydrazodicarboxylate precursor of formula (II). Said base is preferably selected from the group comprising tertiary amines and aromatic amines; triethylamine is a preferred base. In addition to triethylamine, examples of tertiary amines include substituted anilines and diisopropylethylamine. Examples of aromatic amines that may be mentioned include substituted or unsubstituted pyridines and substituted or unsubstituted imidazoles.

According to a preferred embodiment of the invention, step 3 is carried out in the presence of a solvent S, preferably chosen from alkanes and ethers, and more preferably still selected from the group comprising tetrahydrofuran (THF). ), toluene, heptane, cyclohexane, dichloromethane and mixtures thereof (mixture of tetrahydrofuran (THF) and dichloromethane, for example); tetrahydrofuran (THF) is particularly preferred.

The solvent S may be optionally removed from the reaction medium obtained at the end of step 3. This optional removal of the solvent S may be carried out by any appropriate separation means, preferably by distillation.

By way of example, the process according to the invention concerns the preparation of a hydrazino-silane compound (precursor of an azosilane compound), of formula: / \ HHH

(EtO) ₃ If ' ^X N - π - NN - π- OEt

O method in which:

a precursor is prepared and / or implemented

an alkoxylated hydrazodicarboxylate precursor of formula ClCONHNHCOOEt is prepared and / or implemented

- the precursor is reacted

_w ith precursor ClCONHNHCOOEt _{s in} the presence of a solvent S, preferably tetrahydrofuran (THF)

the solvent S is eliminated, preferably by distillation

A H H H

(EtO) ₃ If ' ^x N - π - NN - π - OEt

the compound o o is recovered, preferably by passage in the solid state, followed by filtration.

In addition to or in substitution for the action of the base, it may be provided, in accordance with the invention, to carry out the removal of the HW by-product, preferably by physical desorption of HW. To do this, it is necessary to shift the solubility equilibrium of HW in the reaction medium. For this purpose, the reaction (for example of condensation) between the precursor H - X ¹ - Z and the alkoxylated (halo) hydrazodicarboxylate precursor of formula (II) can be carried out, in the presence of a solvent S, at a temperature Tr chosen so that, for a given pressure, the reaction medium is at reflux of the solvent S, Tr being (generally after placing in the reactor all the precursor H - X ¹ - Z and the precursor of formula ( H)) preferably included (fed) between -20 ^° C. and the reflux temperature of the solvent S, and more preferably still between 20 ^° C. and the reflux temperature of the solvent S. A temperature range Tr of 40 to 60 ⁰ C may be suitable, particularly in the case where the S solvent comprises THF.

An advantageous embodiment of the invention consists in introducing first into the reactor, whatever the order, the precursor H - X ¹ - Z, the solvent S and the possible base, for example at room temperature. (in particular 20 to 30 ^° C.), and then to lower the temperature of the reaction medium (in particular at a temperature of between approximately -10 and 5 ^° C., in particular between approximately -5 and 0 ^° C., for example equal to 5 ⁰ C), and finally to be added to the reaction medium (in this case cooled), preferably progressively (for example in a few minutes to several hours), the alkoxylated hydrazodicarboxylate precursor of formula (II) (advantageously in the form of a solution in solvent S (for example THF)); the reaction medium can then be heated to the above-mentioned temperature Tr (between 20 ^° C. and the reflux temperature of the solvent S, in particular between 40 and 60 ^° C.), in particular after adding all the precursor hydrazodicarboxylate. alkoxylated compound of formula (II).

According to a preferred practical arrangement, the reaction (for example condensation) of step 3 is carried out under stirring and under atmospheric pressure, for several hours (for example between 2 and 4 hours).

The temperatures indicated in this disclosure correspond to temperatures given at atmospheric pressure. The skilled person is able to make the necessary corrections for a pressure different from the atmospheric pressure.

Preferably, the amounts of reagents used are stoichiometric metric.

The method according to the invention may comprise complementary steps, which preferably consist essentially of: 4.1. recovering the residue of the reaction medium from which S has been removed, in a solvent S ', identical to or different from S and corresponding to the same definition as the latter, toluene being preferred;

4.2. optionally to heat the reaction medium obtained in step 4.1, at a temperature greater than or equal to 30 ^° C., preferably between 40 and 50 ^° C., and even more preferably equal to approximately 50 ^° C., so as to solubilizing the compound (I) without dissolving the salts resulting from the reaction of the base with the HW acid formed at the end of the reaction of the precursor H - X ¹ - Z with the alkoxylated hydrazodicarboxylate precursor of formula (II);

4.3. filtering the salts resulting from the reaction of the base with HW; 4.4. recovering by filtration the hydrazo-silane compound of formula (I) referred to.

The reaction product of the base with HW comprises salts, for example triethylammonium chloride when the base is triethylamine.

Advantageously, the filtration of step 4.3 is carried out hot, substantially at the heating temperature used in the previous step 4.2.

According to a preferred embodiment of the method of the invention: -> X corresponds to an oxygen atom (O); → Y is an ethyl group; -> X ¹ corresponds to -NH-; and → Z corresponds to -UC ₃ H ₆ -Si (OCH ₂ CHs) ₃ .

Advantageously, the alkoxylated hydrazodicarboxylate precursor of formula (II):

Y - X - CO - NH - NH - CO - W (II) is obtained by reaction of (WX ^ ₂ CO with NH ₂ - NH - CO - X - Y.

W is a chlorine atom (Cl); X is an oxygen atom (O);

X ¹ corresponds to a covalent bond, X ¹ being of the same nature as in the hydrazo-silane compound of formula (I) referred to.

In the latter case, and when Y corresponds to an ethyl group (preferred variant), the precursor of formula (II) (ClCONHNHCO ₂ Ethyl) can be obtained by phosgenation of ethyl carbazate as described in particular in patents EP 0065366 or US 4501860 (in particular Examples 1 to 7).

The invention also relates, as new products, to the hydrazosilane compounds of formula (I) (which can be obtained) by the process as described above, and furthermore characterized in that they comprise ( at least) traces of the alkoxylated hydrazoazodicarboxylate precursor of formula (II).

Examples of hydrazo-silane intermediate compounds of formula (I) referred to include, in particular, the following products:

A H H H

(EtO) ₃ If ' ^X N - π - NN - π- OEt oo

(C ₂ H ₅ O) ₃ Si- (CH ₂ ) S -NH-CO-NH-HN-COOCH ₃ (CH ₃ O) sSi- (CH ₂ ) s -NH-CO-NH-HN-COOC ₂ H ₅ (UC ₄ H ₉ O) ₃ Si- (CH ₂₎ _S -NH-CO- NH-HN-COOC ₂ H ₅ (C ₂ H ₅ O) ₂ (me ₃ SiO) Si (CH ₂₎ _S - NH-CO-NH-HN-COOC ₂ H ₅ (C ₂ H ₅ O) ₂ (Me ₃ SiO) Si- (CH ₂ ) S -NH-CO-NH-HN-COOCH ₃ (CH ₃ O) ₂ (Me ₃ SiO) Si- (CH ₂ ) _S -NH-CO-NH-HN-COOC ₂ H ₅ (UC ₄ H ₉ O) ₂ (Me ₃ SiO) Si- (CH ₂ ) _S -NH-CO-NH-HN -COOC ₂ H ₅ (C ₂ H ₅ O) ₂ MeSi - (CH ₂ ) _S -NH-CO-NH-HN-COOC ₂ H ₅ (C ₂ H ₅ O) Me ₂ Si- (CH ₂ ) _S - NH-CO-NH-HN-COOC ₂ H ₅ (C ₂ H ₅ O) ₃ Si- (CH ₂ ) _S -S-CO-NH-HN-COOC ₂ H ₅ (C ₂ H ₅ O) ₃ Si- (CH ₂₎ _S -O-CO-HN-NH-COOC ₂ H ₅ The following examples illustrate the invention without, however, limiting its scope.

EXAMPLES

-I- Reactions

-1.1- General

NH ₂ NH ₂ + EtOCOOEt NH ₂ NHCOOEt + W ₂ CO WCONHNHCOOEt (H) Et = ethyl W = Cl or OEt

EtO O O

WCONHNHCOOE EtO If ^" ~~ ^ ~ NH ₂ EtO OO OEt EtO If""NNN OEt EtO If ^" ~~ ^ N ^A NN ^ OEt EtO HHH

[ox] EtO ^H

(I)

-1.2- Particular

EtO ₂ CHN-NH ₂ + CICOCI

-II- Operating mode

In a 250 mL flask, under nitrogen inerting, 6.65 g of 3-aminopropyltriethoxysilane

(30 mmol) are added to 25 ml of tetrahydrofuran (THF), or toluene, at 25 ^° C.

3.78 g of triethylamine (37.5 mmol) are added to this mixture at 25 ^° C.

The temperature of the reaction medium is lowered to 0 ^° C.

5 g of ethyl chloroformylcarbazate (30 mmol) diluted in 25 ml of THF are added to the reaction medium in 30 minutes (T <5 ⁰ C).

The reaction medium is stirred at the desired temperature until the total consumption of the

3-aminopropyltriethoxysilane (about 3 hours).

The solvent is evaporated under vacuum.

The residue is taken up in 35 ml of toluene, and the reaction medium obtained is then heated to

50 ⁰ C for 2 hours.

The triethylammonium salts are filtered at 50 ^° C.

The filtrate is cooled and the solid formed and desired (8.3 g) is recovered by filtration. -III- Results

Condensation of 3-aminopropyltriethoxysilane with ethyl chloroformylcarbazate (W = Cl).

The results are summarized in the table below. Yields (% mol) are measured by 1H NMR.

The synthesis route according to the invention allows the preparation of the hydrazosilane compound of formula (I) with satisfactory yields and selectivities.

Claims

1.- Process for preparing at least one hydrazo-silane compound of formula (I):

Y - X - CO - NH - NH - CO - X - Z (I) in which:

→ , or an aralkyl group (C ₆ -CiS aryl, C 6 -alkyl

C ₂₀ ), this alkyl, aryl or aralkyl group being substituted or unsubstituted, an oxygen atom, a sulfur atom, a covalent bond or an alkylene group, linear, branched or cyclic, having from 1 to 20 carbon atoms , substituted or unsubstituted;

^→ carbon, or an aralkyl group (C ₆ -CiS aryl, C 6 -alkyl

C ₂₀ ), this alkyl, aryl or aralkyl group being substituted or unsubstituted, an oxygen atom, a sulfur atom or an alkylene group, linear, branched or cyclic, having from 1 to 20 carbon atoms, substituted or not substituted;

— > Y is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 18 carbon atoms or an aralkyl group (C ₆ -CiS aryl, C ₁ alkyl -C ₂₀ ), this alkyl, aryl or aralkyl group being substituted or unsubstituted or being the same as Z and optionally carrying at least one heteroatom; And

→ Z is a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 18 carbon atoms or an aralkyl group

(C ₆ -CiS aryl, C ₁ -C ₂₀ alkyl), this alkyl, aryl or aralkyl group being substituted by at least one polyorganosiloxane group and/or at least one silane group of formula:

in which: — > a, b, c are integers chosen such that a + b + c = 3;

→ R ¹ , R ² , R ³ , R ⁴ and R ⁵ are independently of each other an alkyl group, linear, branched or cyclic, having from 1 to 20 carbon atoms, an aryl group having from 6 to 18 carbon atoms carbon, or an aralkyl group (C ₆ -CiS aryl, Ci-C20 alkyl), this alkyl, aryl or aralkyl group being substituted or unsubstituted and optionally carrying at least one heteroatom;

characterized in that it essentially consists of:

1. to prepare and/or to implement a precursor H - X ¹ - Z, with X ¹ and Z as defined above; 2. to prepare and/or to implement an alkoxylated hydrazodicarboxylate precursor of formula (II):

Y - X - CO - NH - NH - CO - W (II) in which:

W corresponds to a halogen or to OR ⁶ , R ⁶ being a hydrogen atom, an alkyl group, linear, branched or cyclic, having from 1 to 20 carbon atoms, an aryl group having from 6 to 18 carbon atoms, or an aralkyl group (C ₆ -CiS aryl, C ₁ -C ₂₀ alkyl), this alkyl, aryl or aralkyl group being substituted or unsubstituted, and Y, X are as defined above; And

3. reacting said H - X ¹ - Z precursor with said alkoxylated hydrazodicarboxylate precursor of formula (II).

2.- Method according to claim 1, characterized in that, at the end of step 3, the targeted hydrazo-silane compound of formula (I) is recovered.

3.- Method according to claim 2, characterized in that the hydrazo-silane compound of formula (I) is recovered by passing it into the solid state, then filtration.

4.- Method according to claim 1, characterized in that W is a halogen, preferably a chlorine atom.

5.- Method according to one of claims 1 to 4, characterized in that the reaction medium comprises at least one base intended to react with the HW acid formed at the end of the reaction ^of the precursor H -

6.- Method according to one of claims 1 to 3, characterized in that step 3 is carried out in the presence of a solvent S, preferably chosen from alkanes and ethers, and in particular chosen from the group comprising tetrahydrofuran (THF), toluene, heptane, cyclohexane, dichloromethane and mixtures thereof, tetrahydrofuran (THF) being particularly preferred.

7.- Method according to claim 6, characterized in that the solvent S is eliminated from the reaction medium obtained at the end of step 3, preferably by distillation.

8.- Method according to claim 7, characterized in that it comprises the complementary steps which essentially consist of:

4.1. to take up the residue of the reaction medium from which S has been eliminated, in a solvent S', identical to or different from S and meeting the same definition as the latter, toluene being preferred;

4.2. optionally heating the reaction medium obtained in step 4.1, to a temperature greater than or equal to 30 ⁰ C, preferably between 40 and 50 ⁰ C, and, even more preferably, equal to approximately 50 ⁰ C, so as to solubilize the compound of formula (I) without dissolving the salts resulting from the reaction of the base with the HW acid formed at the end of the reaction of the precursor H - X ¹ - Z with the alkoxylated hydrazodicarboxylate precursor of formula (II) ; 4.3. to filter the salts resulting from the reaction of the base with the HW acid;

4.4. recovering by filtration the hydrazo-silane compound of formula (I).

9.- Method according to one of claims 1 to 8, characterized in that the reaction between the precursor H - X ¹ - Z and the alkoxylated hydrazodicarboxylate precursor of formula (II) is carried out in the presence of a solvent S, at a temperature Tr chosen such that, for a given pressure, the reaction medium is at reflux of the solvent S, Tr being preferably between -20 ⁰ C and the reflux temperature of the solvent S.

10.- Method according to one of claims 1 to 9, characterized in that: — > X corresponds to an oxygen atom;

→ Y corresponds to an ethyl group; — > X ¹ corresponds to -NH-; And → Z corresponds to -^C ₃ H ₆ -Si(OCH ₂ CHs) ₃ .

11.- Method according to one of claims 1 to 10, characterized in that the alkoxylated hydrazodicarboxylate precursor of formula (II): Y - X - CO - NH - NH - CO - W (II) is obtained by reaction of ( WX ¹ ^CO with NH ₂ - NH - CO - X - Y.

12.- Method according to claim 11, characterized in that:

— > W corresponds to a chlorine atom; → X corresponds to an oxygen atom; And

— > X ¹ corresponds to a covalent bond and is of the same nature as in the hydrazo-silane compound of formula (I) in question.

13.- Hydrazo-silane compound of formula (I) obtainable by the process according to one of claims 1 to 12, further characterized in that it comprises traces of the alkoxylated hydrazodicarboxylate precursor of formula (II) .