Patent Application
20100145089
The invention relates to a new synthesis pathway for (poly)sulfide alkoxy- and/or halosilanes.
The target end products are, more specifically, alkoxydisilanes in which the two alkoxy silane units are connected to one another by a (poly)sulfide bridge. These alkoxysilanes may be useful in particular as white filler/elastomer coupling agents in elastomer compositions comprising a white filler, in particular a siliceous substance, as a reinforcing filler.
Coupling agents, especially silica/elastomer coupling agents, have been described in a large number of documents, the best-known of these agents being difunctional organoxysilanes which carry at least one organoxysilyl function and at least one function capable of reacting with the elastomer, such as, in particular, a polysulfide functional group.
Patent application WO-A-02/083719 describes polysulfide monoorganooxysilanes with a linking propylene unit, of formula F:
in which the symbols R1, R2, and R3 are monovalent hydrocarbon groups and x is a number ranging from 3±0.1 to 5±0.1. These compounds can be used as white filler/elastomer coupling agents in diene rubber compositions comprising a white filler such as a siliceous substance as a reinforcing filler.
U.S. Pat. No. 5,780,661 describes a process for preparing methyldichlorosilanes functionalized with a sulfur radical. This process consists in reacting allyldichloromethylsilane with a sulfur reactant of the thiophenol, N-propylmercaptan or thioacetic acid type by a free-radical mechanism in the presence of an azobisisobutyronitrile initiator in a reaction chamber under inert gas by heating at 60° C. for 4 to 5 hours.
In this context, one of the key objectives of the present invention is to provide an alternative pathway to alkoxy- and/or halosilanes, especially polysulfide monoalkoxysilanes, more particularly those as defined by the above formula (F).
Another key objective of the invention is that this alternative synthesis pathway should be simple and economic to exploit.
These objectives, among others, are achieved by the present invention, which firstly provides a process for preparing at least one (poly)sulfide alkoxy- and/or halosilane, characterized
in which:
The invention secondly provides sulfide alkoxy- and/or halosilanes capable of being intermediates in the process according to the invention as defined above, of formula (III):
in which:
an acyl radical —R10—CO—OR8, with R10 representing an alkylene having 1 to 20 carbon atoms, preferably a methylene;
It is to the merit of the inventors to have provided a new synthesis pathway which is radically different from the synthesis pathways known for the preparation of polysulfide alkoxysilanes, which involve reacting at least one alkoxysilane with sulfide reactants.
In contrast to this the invention proposes reacting an alkoxy- and/or halosilane (I) which is functionalized, preferably with an alkenyl function, for example having a terminal allyl moiety, with a sulfur reactant (Rs), in particular in the absence of free-radical initiator.
The new pathway according to the invention is based on a free-radical addition mechanism which is easy to implement and is economic.
(Rs) and (I) react in such a way that a free-radical addition mechanism is involved.
Moreover, entirely surprisingly and unexpectedly, this free-radical addition mechanism is (virtually) spontaneous. It does not require activation, whether by addition of free-radical initiator(s) and/or actinic activation (photonic activation: for example, tank under UV lamp, particularly HP Hg lamp) and/or thermal and/or ultrasonic activation and/or by electron bombardment.
It is nevertheless entirely possible, according to one version of the invention, to provide for such activation.
With reference to the activation by means of free-radical initiator(s), this is prohibited, in accordance with the invention, where at least two of the radicals R1 each correspond to a halogen. In this context it should be specified that the expression “the reaction mixture is (virtually) free of free-radical initiator(s)” signifies in particular that the reaction mixture does not contain free-radical initiator or contains only traces of free-radical initiator(s), in other words in an amount which is insufficient to give rise to activation of the free-radical reaction (for example, less than or equal to 0.1% by weight).
Where at least two of the radicals R1 are each different from a halogen, it is possible, but not vital, to employ at least one free-radical initiator.
Similarly, actinic activation (photonic activation: for example, tank under UV lamp, particularly HP Hg lamp) and/or thermal and/or ultrasonic activation and/or by electron bombardment may be employed. In practice it is preferred to employ thermal activation, which generally involves heating the reaction mixture to a temperature between ambient temperature and 120° C., preferably between 50 and 110° C., for standard atmospheric pressure.
This new synthesis pathway is simple and unrestrictive from an industrial standpoint.
Preferably the silane of formula (I) is such that at least one (more preferably only one) of the radicals R1 is —OR2.
The (poly)sulfide alkoxysilanes and halosilanes obtained by the process according to the invention advantageously comprise a polysulfide unit [S]x.
According to one preferred feature of the invention, Y corresponds to the formula (II) below:
in which:
Preferably the (free-radical) addition of (Rs) is on the gamma (γ) carbon of the alkoxy- and/or halosilane (I).
In a particularly advantageous and surprising way, the addition according to the invention to this terminal alkenyl moiety Y of formula (II) of the silane (I) enjoys a high total regioselectivity and a high isolated yield, of greater than 90%, for example; this total regioselectivity signifies that the double bond of the radical Y reacts with the sulfur reactant (Rs) without secondary reaction.
The alkoxy- and/or halosilane of formula (I) that is used in the process according to the invention may be obtained by reacting at least one halo- and/or alkoxysilane with at least one halogenated organic compound, preferably an allyl halide, in the presence of at least one metal selected from the group consisting of Mg, Na, Li, Ca, Ba, Cd, Zn, Cu, mixtures thereof, and alloys thereof (preferably magnesium), in the presence of an ethereal organic solvent and/or an acetal solvent, by a mechanism based on the Barbier reaction.
Another pathway for synthesizing the starting alkoxy- and/or halosilane of formula (I) may be a more traditional pathway, in particular in which a trialkoxysilane and/or a trihalosilane functionalized with a haloalkyl group is employed, by a Grignard reaction mechanism involving a halomagnesium Grignard reagent, namely MeMgCl. This synthesis pathway is described in particular in patent applications JP-A-2002179687 and WO-A-03/027125.
According to another advantageous embodiment of the process according to the invention, the sulfur reactant (Rs) is selected from the group consisting of H2S, HS—CO—R8, HSR8, HSCSR8, HSCS—NR82, HSCS—OR8, and mixtures thereof, the symbol R8 corresponding to:
These reactants (Rs) are economic and readily available. Thus the above reactants (Rs) are described in the very extensive literature relating to thiols, and, for example, in U.S. Pat. No. 5,780,661.
The (free-radical) addition reaction of the silane of formula (I) with these reactants (Rs) leads to intermediate compounds which are thiols when (Rs) corresponds to HSH or mercaptan derivatives having terminal moieties —S—CO—R8, —SR8, —SCS—R8, —SCS—NR82 or —SCS—OR8 when (Rs) corresponds to HS—CO—R8, HSR8, HSCS—R8, HSCS—NR82 or HSCS—OR8, respectively.
According to one variant embodiment (V1) in which (Rs) corresponds to HS—CO—R8, HSR8, HSCS—R8, HSCS—NR82 or HSCS—OR8, the product from the reaction between (I) and (Rs) is reacted with at least one transesterification/amidation reagent (Rt) allowing conversion of the thioester having a terminal moiety —S—CO—R8, —SR8, —SCS—R8, —SCS—NR82 or —SCS—OR8 to a thiol function —SH. (Rt) is selected from the group of reagents capable of reacting by a mechanism of nucleophilic addition to the carbon of the thioester function, preferably from the group consisting of alcohols (for example, ethanol), amines (for example, ammonia), preferably primary amines, hydrogen sulfide, and mixtures thereof.
If (Rt) is an alcohol, the reaction is a transesterification; if (Rt) is an amine, the reaction is a transamidation.
Especially in the case where a reagent (Rt) is used that is selected from alcohols, this transesterification may be carried out in the presence of at least one base, preferably selected from the group consisting of carbonates (advantageously K2CO3 or Na2CO3), phosphates (advantageously K3PO4), alkoxides (advantageously CH3CH2ONa), and mixtures thereof.
According to a variant embodiment (V2), in which (Rs) corresponds to HS—CO—R8, HSCS—R8, HSCS—NR82 or HSCS—OR8, the silane (I) is reacted with the sulfur reactant (Rs) so as to join the terminal radical R5 of the group Y of the silane (I) to a terminal moiety —S—CO—R8, —SCS—R8, —SCS—NR82 or —SCS—OR8. The resulting intermediate is reacted with HSH to convert the terminal moiety —S—CO—R8—SCS—R8, —SCS—NR82 or —SCS—OR8 to a thiol function —SH and so to produce a thiol intermediate, while reconstituting (Rs), which hence plays the part of a relay molecule.
The reaction scheme below illustrates, without limitation, the variant V2 with a relay molecule
in which Z1 may correspond to O and Z2 to —OR2 with R2 as defined above.
This relay molecule can be used in situ. For example, for H—SCOCH3, it is possible to carry out beforehand the reaction between acetic anhydride and H2S:
CH3—CO—O—CO—Me+H2S→H—S—COCH3+HO—COCH3, or the reaction between NaHS and ClCOCH3.
In accordance with the invention it is possible to prepare specified polysulfide alkoxysilanes, namely alkoxydisilanes or bisalkoxysilanes, in which the alkoxysilyl units are joined to one another by a sulfur bridge containing one or more sulfur atoms.
To do this it is appropriate to employ the thiol intermediate obtained directly by reaction of the silane (I) with a reactant (Rs) corresponding to HSH, or indirectly by reaction of the silane (I) with a reactant (Rs) corresponding to HS—CO—R8, HSCS—R8, HSCS—NR82 or HSCS—OR8, then with the transesterification reagent (Rt) in accordance with variant (V1), or with HSH in accordance with variant V2.
This thiol intermediate is advantageously reacted with a secondary sulfur reactant (Rs2) selected from the group consisting of Sx and/or X1S—SX2, with the symbol x corresponding to a whole or fractional number ranging in general from 1 to 10, preferably from 1 to 5, and more preferably from 1.5 to 5, in particular between 3 and 5, for example between 3.5 and 4.5, the end points of these ranges being accurate to +/−0.2, and X1 and X2 representing independently a halogen, preferably chlorine, this secondary sulfidation being advantageously carried out in a basic medium comprising as base, for example, K2CO3, Na2CO3, K3PO4, (CH3CH2)ONa or mixtures thereof.
In addition to the qualitative aspects relating to the nature of the silane (I) and of the sulfur reactant (Rs), the process according to the invention also integrates advantageous quantitative aspects. Thus the molar (I)/(Rs) ratio is in particular between 5 and 0.1, preferably between 3 and 0.5, and more preferably between 2 and 0.7.
According to one variant, the reaction between (Rs) and (I) (free-radical addition) in the process according to the invention may be carried out under an inert atmosphere and/or, optionally, with the aid of at least one free-radical initiator, such as azobisisobutyronitrile (AIBN), for example.
Advantageously the process according to the invention comprises at least one step of hydrolysis allowing at least one of the radicals R1 that corresponds to —OR2 of the (poly)sulfide alkoxy- and/or halosilane to be converted to a silanol.
The products obtained by the process according to the invention that are specifically targeted are polysulfide disilanes (or bis-silanes) comprising polysulfide alkoxysilanes and/or halosilanes of formula (IV):
in which:
More particularly, two of the substituents R1 of at least one of the two terminal silicons are alkyl radicals, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, CH3O—CH2— or CH3O—CH(CH3)CH2— (for example, methyl, ethyl, n-propyl or isopropyl), or aryl radicals, for example phenyl, these two substituents R1 being preferably methyls; the third substituent R1 is preferably an alkoxy —OR2, preferably with R2 corresponding to methyl, ethyl, n-propyl, isopropyl, n-butyl, CH3O—CH2— or CH3O—CH(CH3)CH2— (for example, methyl, ethyl, n-propyl or isopropyl).
More particularly the polysulfide disilanes preferably obtained by the process according to the invention correspond to the formula (IV.1):
in which:
The alkoxysilanes corresponding to the formula (IV.1) which are especially targeted by the present invention are those for which:
R1.1 and R1.3 each represent a methyl and
R6 and R7 represent a hydrogen, and
radicals R1-2, which are identical, each represent a methoxy, an isopropyl or, preferably, an ethoxy, and the symbol x corresponds to a whole or fractional number between 1.5 and 5, in particular between 3 and 5, advantageously between 3.5 and 4.5, the end points of these ranges being given to an accuracy of +/−0.2.
The process according to the invention is directed in particular to the preparation of alkoxysilanes corresponding to formula (IV.1) in which R1.1 and R1.3 each represent a methyl, R6 and R7 represent a hydrogen, radicals R1.2, which are identical, each represent an ethoxy, and the symbol x corresponds to a whole or fractional number between 3 and 5, advantageously between 3.5 and 4.5, the end points of these ranges being given to an accuracy of +/−0.2.
The symbol x in the formulae (IV) and (IV.1) is a whole or fractional number which represents the number of sulfur atoms present in a molecule of formula (IV) or (IV.1).
This number may be an exact number of sulfur atoms, where the synthesis pathway of the compound in question is able to give rise to only one variety of polysulfide product.
In practice this number tends to be the average of the number of sulfur atoms per molecule of compound in question, in so far as the synthesis pathway selected generally tends to give rise to a mixture of polysulfide products each having a different number of sulfur atoms. In that case the polysulfide compounds synthesized are in fact composed of a distribution of polysulfides, ranging from the monosulfide or the disulfide S2 to heavier polysulfides (for example S≧5), centered on an average molar value (value of the symbol x) which is situated within the general ranges referred to above. Advantageously the polysulfide mono-organoxysilanes synthesized are composed of a distribution of polysulfides comprising a molar figure of (S3+S4) of greater than or equal to 40% and, preferably, greater than or equal to 50%; and of (S2+S≧5) of less than or equal to 60% and, preferably, less than or equal to 50%. Moreover, the molar proportion of S2 is advantageously less than or equal to 30% and, preferably, less than or equal to 20%. All of the limit values are given to the accuracy of measurement (by NMR), with an absolute error of approximately ±1.5 (for example 20±1.5% for the last proportion indicated).
Some of the polysulfide compounds obtained with the process according to the invention, especially the alkoxysilanes containing a polysulfide bridge connecting two alkoxysilane residues, more particularly those of formula (IV), preferably of formula (IV.1), can be used as a white filler/elastomer coupling agent in compositions comprising at least one diene elastomer and a white filler (especially a precipitated silica) as a reinforcing filler, said compositions being intended, for example, for the manufacture of diene elastomer articles.
The new synthesis pathway proposed in the first subject of the invention, as described above, is highly advantageous in particular in that it leads to new sulfide alkoxy- and/or halosilanes which are intermediates. In its second subject, the invention is therefore directed to these new sulfide alkoxysilanes and/or halosilanes, whether or not they are intermediates in the process in accordance with the first subject of the invention.
These new sulfide alkoxy- and/or halosilane products are products of above-defined formula (III).
In one preferred embodiment of the sulfide alkoxy- and/or halosilanes of formula (III), two of the substituents R1 are alkyl radicals, preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, CH3O—CH2— or CH3O—CH(CH3)CH2—(for example, methyl, ethyl, n-propyl or isopropyl), or aryl radicals, for example phenyl, these two substituents R1 being preferably methyls; the third substituent R1 is preferably an alkoxy —OR2, in particular with R2 corresponding to methyl, ethyl, n-propyl, isopropyl, n-butyl, CH3O—CH2— or CH3O—CH(CH3)CH2—(for example, methyl, ethyl, n-propyl or isopropyl).
The products of formula (III) which are especially targeted by the present invention are sulfide alkoxysilanes, more particularly sulfide alkoxysilanes of formula (III.1):
in which the symbols R1.1, R1.2 and R1.3, which are identical or different to one another, correspond to one of the definitions given above for R1; R11 being as defined above (in formula (III)); R1.1 and R1.3 corresponding preferably to an alkyl (advantageously methyl or ethyl), and R1.2 corresponding preferably to an alkoxy (advantageously methoxy or ethoxy).
One such example of sulfide alkoxysilane is a compound of formula (III.1.1):
(CH3CH2O)(Me)2SI—(CH2)3—S—CO—(CH2)5—CH3 (III.1.1)
The examples which follow illustrate the invention, but without limiting its scope.
A 10 ml reactor is charged under argon with 1.00 g (6.94 mmol) of allyldimethylethoxysilane and 0.8 g (7.17 mmol) of HS—CH2—CO2Et. This charge is left to react at 100° C. for 16 hours. GC analysis shows a degree of conversion of more than 98%.
The product is the ethyl ester of [3-(ethoxydimethylsilanyl)propylsulfanyl]acetic acid. The addition derivative is obtained with a virtually quantitative yield and a regioselectivity of more than 99%.
A 10 ml reactor is charged under argon with 1.01 g (7.02 mmol) of allyldimethylethoxysilane and 0.55 g (7.04 mmol) of 2-mercaptoethanol. This charge is left to react at 60° C. for 16 hours. The degree of conversion of the starting materials is complete. The structural analyses show that the reaction mass is composed very primarily (>90 mol %) of the following derivative:
The regioselectivity is greater than 99%.
A 10 ml reactor is charged under argon with 1.00 g (6.96 mmol) of allyldimethylethoxysilane and 0.81 g (6.96 mmol) of cyclohexyl mercaptan. This charge is left to react at 60° C. for 16 hours. The degree of conversion of the starting materials is complete. The structural analyses show that the reaction mass is composed very primarily (>80 mol %) of the following derivative:
The regioselectivity is greater than 99%.
A 10 ml reactor is charged under argon with 1.08 g (7.57 mmol) of allyldimethylethoxysilane and 1.18 g (7.70 mmol) of thiobenzoic acid. This charge is left to react at 60° C. for 16 hours. The degree of conversion of the starting materials is complete. The structural analyses show that the reaction mass is composed very primarily (>75 mol %) of the following derivative:
The regioselectivity is greater than 99%.
A 10 ml reactor is charged under argon with 1.08 g (7.57 mmol) of allyldimethylethoxysilane and 7.60 mmol of thioacetic acid. This charge is left to react at 60° C. for 16 hours. The degree of conversion of the starting materials is complete. The structural analyses show that the reaction mass is composed very primarily (>75 mol %) of the following derivative:
The regioselectivity is greater than 99%.
Addition of thioacetic acid to dimethylethoxyallyl-silane under air
A 100 ml three-necked flask with a condenser, a temperature probe, an oil bath, and a magnetic stirrer is charged with the following under air:
This charge is heated at 60° C. for 3 hours. The degree of conversion is greater than 99% (GC analysis).
30.5 g of a colorless liquid are recovered.
The 1H and 13C NMR analyses confirm the structure of the product formed:
(CH3CH2O)Si(CH3)2—CH2—CH2—CH2—S—C(O)—CH3
with a purity of greater than 95 mol % and a virtually quantitative yield.
A 50 ml round-bottomed flask with magnetic stirrer is charged under argon with 8.08 g of 3-(ethoxydimethylsilyl)propylthioacetic ester (36.7 mmol, 1 eq.), 1.08 g of potassium carbonate (7.82 mmol, 0.21 eq.), and 40 ml of absolute ethanol degassed with argon (686 mmol, 18.67 eq.).
The reaction mixture is left with stirring at 70° C. for 3 hours. The degree of conversion is 100%. The reaction mixture is then filtered under an inert atmosphere, evaporated, and distilled under vacuum.
This gives a distillation fraction containing 98% of thiol of interest and of mass m of 5.58 g of product, or an isolated yield of 85%.
The structural analyses confirm the formation of the following product:
CH3CH2O(CH3)2Si—(CH2)3—SH
In a Schlenk with guard tube and magnetic stirrer and a bubbling tube with frit.
20 ml of absolute ethanol degassed with argon (340 mmol, 38 eq.) and 2.00 g of 3-(ethoxydimethyl-silyl)propylthioacetic (9.13 mmol, 1 eq.) are introduced.
The ammonia is released and is bubbled in gently and as required.
The hydrolysis reaction is exothermic. The degree of conversion becomes complete after 8 hours.
The reaction mixture is then evaporated in order to remove the ethanol, and the residue is taken up in pentane and filtered; the filtrate is then evaporated. This gives a colorless mobile oil with a strong thiol odor and a mass m of 1.64 g.
The yield is virtually quantitative.
Structural analysis confirms the presence of the following compound, with a molar purity of greater than 75%:
CH3CH2O(CH3)2Si—(CH2)3—SH
The secondary product is the acetamide.
The yield is therefore 90%.
In a 25 ml three-necked flask with a condenser, a temperature probe, a cold bath, and magnetic stirring, the following are introduced under argon:
The reaction mixture is cooled to 0° C. 387 mg of sulfur dichloride (Cl2S2) are run in over 5 minutes. The reaction is highly exothermic and the temperature of the reaction mixture climbs to 10° C. It is kept with vigorous stirring for 15 minutes and then left to return to ambient temperature. The salts formed are isolated by filtration, washed with pentane and evaporated to dryness.
This gives a yellow oil with a mass of 1.21 g, with a quantitative weight yield.
The 1H and 13C NMR analyses confirm the structure of the product formed:
(CH3CH2O)Si(CH3)2—CH2—CH2—CH2—Sx—CH2—CH2—CH2
—Si(CH3)2(OCH3CH2)
and allow the following to be ascertained: average M of 399.6 g.mol−1, with an average number x of 3.4.
In a strictly dry 25 ml single-necked flask with condenser and oil bath, and under air, 1.0182 g (1.02 mmol) of n-thiooctanoic acid (1 molar equivalent) and 667.7 mg (1.00 mmol) of ethoxydimethylallylsilane (1 molar equivalent) are introduced. The mixture is stirred at 60° C. For 48 hours, the reaction is monitored by gas chromatography. The reaction mixture is left to cool and a mobile yellow oil is recovered (with a mass m of 1.045 g) of the derivative
(CH3CH2O)(CH3)2Si—(CH2)3—S—CO—(CH2)6—CH3, of which the NMR and IR analyses confirm the structure.
In a 40 ml Hastelloy reactor, under autogenous pressure, with magnetic stirrer and oil bath, and under an argon atmosphere, 2.0 g of (3-propylethoxydimethyl-allylsilane)thioacetic ester (8.91 mmol, 1 eq.) and 1.34 g of polysulfane (9.23 mmol, 1.04 eq.) are introduced. The two liquids are not miscible.
The reactor is closed and the reaction mixture is heated at 150° C. for 16 hours with stirring.
It is left to cool and then the reactor is opened. It contains a liquid mixed with sulfur. The reactor contents are filtered to give an oil with a mass m of 3.47 g, with a yield of 93%.
NMR and IR analyses confirm the formation of the derivative
CH3CH2O(CH3)2Si—(CH2)3—Sx—(CH2)3—Si(CH3)2OCH2CH3 with an average number x of 4.
In a 40 ml Hastelloy reactor, under autogenous pressure, with magnetic stirrer and oil bath, and under an argon atmosphere, 2.05 g of ethoxydimethylallyl-silane (13.90 mmol, 1 eq.), 967 mg of flowers of sulfur (30.2 mmol, 2.17 eq.) and 4.3 ml of anhydrous isopropanol (56.2 mmol, 4.04 eq.) are introduced. The solid and liquid reactants are not miscible.
The reactor is closed and the reaction mixture is heated at 150° C. for 16 hours with stirring.
It is left to cool and then the reactor is opened. It contains a liquid mixed with sulfur. The reactor contents are filtered to give an oil with a mass m of 3.78 g, with an isolated yield of 65%.
NMR and IR analyses confirm the formation of the derivative
CH3CH2O(CH3)2Si—(CH2)3—Sx(CH2)3—Si(CH3)2OCH2CH3, with an average number x of 4.
An 80 ml Hastelloy reactor pelletized at the upper limit of useful pressure of 200 bar, with a magnetic stirrer and resistance heater, is charged under an argon atmosphere with 30 g of ethoxydimethylallylsilane (208 mmol, 1 eq.). 28 bar of H2S are added.
The reactants are brought together; the H2S pressure is maintained constant during the operation, by successive additions of gas.
The reaction mixture is heated from ambient temperature to 150° C. over 20 hours, followed by a plateau at 150° C. for 15 hours.
At the end of the reaction, the temperature is lowered to ambient temperature again and the remaining H2S is degassed. The degree of conversion is approximately 30%.
The reaction mixture is subsequently distilled under vacuum. This gives a mass of 10.9 g of a distillation fraction with a purity of greater than 95%.
The structural analyses confirm the addition of the hydrogen sulfide in gamma position.
In a 40 ml Hastelloy reactor, under autogenous pressure, with magnetic stirrer and oil bath, and under an argon atmosphere, 820 mg of 3-thiopropyl-ethoxydimethylsilane (4.60 mmol, 1 eq.) and 271 mg of flowers of sulfur (8.46 mmol, 1.84 eq.) are introduced. The solid and liquid reactants are not miscible.
The reactor is closed and the reaction mixture is heated at 150° C. for 16 hours with stirring.
It is left to cool and then the reactor is opened. It contains an orange liquid mixed with sulfur. The reactor contents are filtered to give an oil with a mass m of 838 mg, with a yield of 87%.
The oil contains virtually exclusively the following product:
CH3CH2O(CH3)2Si—(CH2)3—Sx—(CH2)3—Si(CH3)2OCH2CH3, with an average number x of 4.
A perfectly dry 25 ml three-necked flask under argon, equipped with a condenser, temperature probe, magnetic stirrer, and cold bath, is charged with the following in this order:
From the start of the introduction of the first drops of Cl—S—S—Cl, the reaction mass, which was clear, becomes turbid, with formation of a white precipitate with a slight yellow tinge. The reaction is exothermic and the introduction is made over 30 minutes.
At the end of the introduction, the reaction mixture is heterogeneous and orange-yellow; it is filtered on a number 4 frit; the filtrate is evaporated, then taken up in pentane, filtered again, and sucked dry.
This gives a mass m of 1.21 g of a clear, mobile yellow oil, with a yield of 97%.
The structural analyses confirm the presence of the following product, with a molar purity of greater than 97%:
CH3CH2O(CH3)2Si—(CH2)3—Sx—(CH2)3—Si(CH3)2OCH2CH3, with an average number x of 3.7.
| Number | Date | Country | Kind |
|---|---|---|---|
| 0609836 | Nov 2006 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2007/062166 | 11/9/2007 | WO | 00 | 11/18/2009 |
