CS36191A2 - Method of polyfosfazenes preparation by means of polydichlorofosfazenes substitution - Google Patents

Description

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Process for preparing polyphosphazenes by substitution of polydichlorophosphazenes

Technical field

The present invention relates to a process for preparing polyphosphazenes by substituting polydichlorophosphazenes in a hydrocarbon medium.

Background Art

Polyphosphazenes represent a group of polymers formed. the mineral phosphorus chain, in which the phosphorus bears substituents of various nature. These polymers may in particular contain a plurality of structural units of the formula I:

R

AND

N = P i wherein R, which may be identical or different in one and the same structural unit or in single structural units, are radicals selected from the group consisting of alkyl radical, aryl radical, alkoxy radical, fluoroalkoxy a radical, an aryl oxy radical, an alkyl sulfide radical, an arylsulfide radical, an alkylamino radical or an arylamino radical.

These polymers are obtained from polydichlorophosphazenes - 2 - of the general formula II:

a / 11 / '| and. by substituting chlorine atoms for nucleophilic compounds according to the following reaction scheme:

Cl

N = P

AND

Cl + XR - + XC1 wherein X is in particular a hydrogen atom or an alkali metal atom and R is as defined above. Numerous compounds are described in the literature with nucleophilic nature. The major representatives of these nucleophilic compounds are the phenolates and the alcoholates /, in particular, the fluorinated alcoholates / associated with sodium ion.

To carry out the above substitution, two types of reaction media are proposed: ® - ethers / tetrahydrofuran, ethylene glycol ethers, - dioxane, which allow substitution in homogeneous phase (H). Allcock et al., Inorg, Chem. 2/10 /, 1709, 15 »/1966/Austin..et Coll. Ivicro-molecules 16 (5), 719-22 (1983); hydrocarbons in which the phenolates and the alcohol-3-salts are insoluble or partially soluble (Austin wheels). Macromolecules 16 (5), 719-22 (1983), H.R. Penton, U.S. Pat. No. 4,514,550

Substitution carried out in hydrocarbon medium - .benzene, toluene, xylenes, cyclohexane, etc. - has many advantages over substitution in ether medium, among which: lower costs and often weaker toxicity, ease of drying, lower degree of degradation in the course of substitution and the easy removal of sodium chloride formed as a by-product either by washing the reaction medium with water or simply by filtration.

Conversely, when any hydrocarbon is used, there are always some nucleophilic agents that are completely insoluble in the hydrocarbon and, consequently, some degree of conversion is not further substituted with chlorine atoms. The thus-substituted polyphosphazenes then retain a high residual chlorine content, resulting in partial degradation of the polymer during extraction and washing, which in turn results in a lower molecular weight of such polymer. Also, the yield of said substitution reaction is relatively low.

Moreover, substitution of chlorine atoms of polydichlorophosphazene with alcoholates also poses specific problems. It is well-known that, in parallel with the substitution reaction, there is also a competitive chain splitting reaction, leading to a strong reduction in the average molecular weight of the polymer and k

Obtaining a very low molecular weight fraction. Such a competitive degradation reaction is much more applicable to alcoholates than to phenolates. In addition, the problem of fluorinated alcoholates is their degradation due to the attack of their fluorine atoms by their own alcoholate function. Therefore, the yields reported in the literature for the substitution of - 4 - fluorinated alcohols in an ether medium are very low / H.R. Allcock et al. Inorg. Chem. £ (10), 1709, 15, (1966) or K.A. Reynard et al. U.S. Patent No. 3,896,058;

These specific problems that occur with the substitution of alcoholates may be minimized by the fact that. if the substitution is carried out in a hydrocarbon environment as low as possible in order to limit the nucleophilic nature and thus the aggressiveness of the alcoholate anions. However, if the substitution is carried out under these conditions, it is not possible to achieve complete substitution of the atoms with chlorine as a result of the insolubility of the alcoholates, the higher the is operated at a lower temperature. In order to solve this problem associated with the inadequate solubility of both some phenolates and alcoholates, P.E. Austin et al. in Macromolecules 16 (5), 719-22 (1983) to carry out said substitution in the presence of quaternary ammonium salts. In the case of phenolates, this process does not allow to work solely in the presence of a hydrocarbon as solvent, without the progress of the substitution being stopped at an insufficient degree of conversion and hence without a high residual chlorine content. The thermal stability of the quaternary ammonium salts is very limited, so that it is possible to operate at elevated temperatures necessary for the substitution of the phenolates which exhibit increased steric hindrance. Although the use of the castrate ammonium salts makes it possible to substitute the alcoholates in the pure hydrocarbon environment, the yields thus obtained remain low. Austin et al. Macromolecules 16 (5), 719-22 (1983). zenu.

The invention therefore provides an improved process for preparing polyphosphazene by substituting chlorine atoms for polydichlorophospha- 5 -. In particular, the invention proposes a method for achieving an increased degree of substitution by phenolates. and alkali metal alcoholates.

The invention also provides a method for producing a higher yield of substituted polymer.

Other advantages of the method of the invention will be apparent from the following.

SUMMARY OF THE INVENTION The present invention provides a process for the preparation of polyphosphazenes by substituting polydichlorophosphazene with nucleophilic reagents in a hydrocarbon environment which consists essentially of partially or partially substitution reaction in the presence of a polyether.

In general, the polyether may be used in an amount of at least 0.1% by weight based on the weight of the nucleophilic reagent. Preferably, the amount does not exceed 10% by weight.

In order for these polyethers to have sufficient efficiency, they must be formed by a chain comprising an ether number in the function of at least 4. This chain may be terminated by both a hydroxyl function or an ether function or terminated by a hydroxyl function at one end and an ether function at the other end. .

In particular, the chain may be an ethylene oxide chain, a propylene oxide chain, or a combination of both.

J

These polyethers, hereinafter referred to as catalysts, may be included in the following general formula III: -. R 1 in which 0 - C x H 2 X - O R 2/111 / n is an integer at least 4, x is 2 or 3 and R 1 and R 2, which may be identical or different, may be a hydrogen atom, an alkyl radical containing. 1 to 24 carbon atoms, a mono- or polycyclic aryl radical containing up to 18 carbon atoms or an alkylaryl or aralkyl radical, their alkyl and aryl moieties are the same as the above-defined alkyl and aryl radicals. In formula III, n is generally greater than 20 and is preferably in the range of 5 to 200.

Examples of said polyethers are, in particular, polyethers of formula III wherein one of the general symbols R 1 or R 2 is hydrogen and the other is an alkylaryl radical, especially an alkyl aryl radical containing 8 to 20 carbon atoms. In the process of the invention, the introduction of the catalyst can be carried out at any time during the substitution reaction. This introduction can be carried out at the outset together with the introduction of other reactants. It can also be done up to. after a period of time during which the substitution course arrives to a degree that is achievable in the absence of the catalyst.

As mentioned, the -7- substitution reaction is carried out in a hydrocarbon medium, wherein the hydrocarbon medium may be an aromatic hydrocarbon, a cycloaliphatic hydrocarbon, or an aliphatic hydrocarbon such as one of the hydrocarbons described above or mixtures thereof. Do. It is also within the scope of the present invention to use a mixture of hydrocarbons and ethers as the solvent of the substitution reaction medium, for example, the ether ether may be introduced together with the hydrocarbon or until the reaction medium in the reaction medium. of the substitution reaction.

The substitution reaction is generally carried out at a temperature of from about 0 ° C to about 220 ° C, particularly depending on the nucleophilic reagent used and the vapor pressure of the solvent used.

The process of the invention makes it possible to obtain polyphosphatises in increased polymer yield and substitution yields close to 100 [deg.], But in any case higher in yield than 95%, whereby the obtained polymer, also within the scope of the invention, has a higher molecular weight than in cases where it has been obtained by conventional methods known in the art. EXAMPLE 1 (Comparative 1a) 18.3 g (0.193 mol) of phenol and 225 g of xylene are introduced into a reactor under nitrogen pressure, with 50 g of xylene being distilled off to provide dehydration of the reaction medium. The moisture content is thereby reduced to at least 10 ppm. To this rofctoku se. then 5.15 g (0.172 mol) of sodium hydride are added. The reaction to form sodium phenolate is stirred for 2 hours at 140 ° C. The suspension of sodium phenolate in xylene is then cooled to 120 DEG C. and 9.06 g (0.156 chlorine equivalent) of poly-dichlorophosphazene dissolved in 18 g of trichlorodiphenyl are introduced into it at this temperature.

The mixture was reacted for 24 hours at 140 ° C.

The reaction mixture is then neutralized with concentrated hydrochloric acid and filtered through a layer of diatomaceous earth. The xylene is evaporated until a syrup is obtained and the residue is poured into 500 ml of methanol. After centrifugation, the polymer is redissolved in the minimum amount of tetrahydrofuran and re-precipitated in 500 ml of methanol. The last operation is repeated once more. The final polymer is finally dried under reduced pressure at 80 ° C / 133.3 Pa Pa. 12.86 g of polydiphenoxyphosphazene, yield 71.3%, are obtained. This polymer has the following properties - residual chlorine content: 0.64% by weight, - limit viscosity number: 64.3 ml / g, - Mw Example 2 * Preparation of sodium phenolate was carried out according to the procedure of paragraph 1a of Example 1 from 18.24 g (0.194 mol) phenol, 225 g xylene and 5.1 6. (0.172 mol) sodium hydride.

The substitution reaction is carried out according to paragraph 1b of Example 1 using 8.88 g (0.153-chlorine equivalent) of - 9 -? - L? I and the same polydichlorophosphazene. The reaction mixture was then maintained at 140 ° C for 20 hours. The reaction mixture is then treated with 0.44 g of nonylphenol ethoxylated with 100 molecules of ethylene oxide per mole of non-phenol (2.2% based on the weight of sodium phenolate) and maintained for 20 hours at 120 ° C. .

The resulting polymer was isolated and purified by the procedure of 1b of Example 1. 14.78 g (yield: 83.6%) of a polymer having the following analytical characteristics was obtained: residual chlorine content: 0.062% by weight; number: 83.6 ml / g, - Mw / light diffusion / 809,000. Example 3

In a 30 liter reactor equipped with a turbine stirrer and pressurized with nitrogen, 4445 gtoluene, 14504 g xylene and a mixture of phenols containing 49.94 geugenol, 496 g phenol, and 815 g p-ethylphenol / 0.304 mole, 5.271 mole, respectively, were introduced. 6.671 moles /. This solution was dried by distilling 5266 g of solvent (moisture content of at least 10 ppm). The mixture is then charged with 253 g of sodium (11 moles). The reaction mixture is brought to reflux and the stirring speed is increased to 3000 rpm. The evolution of hydrogen ceases completely after 40 minutes, after which the reaction conditions are complete. maintained for 2 hours.

The reaction mixture is then cooled to 110 DEG C. and 571.83 g of polydichlorophosphazene (9.86-chlorine equivalent) dissolved in 1235 g of trichlorobenzene are introduced. The mixture is then heated to 120 ° C for 20 hours and 32 g of nonylphenol ethoxylated with 100 molecules of ethylene oxide are added. The reaction mixture was then maintained at 120 ° C for 20 hours.

After cooling, the reaction mixture was slightly acidified by the addition of concentrated hydrochloric acid and filtered through a pad of diatomaceous earth. The reaction mixture is then concentrated to about one third of its own; volume and precipitated in 60 liters of methanol. The precipitated gum was washed in the malax two times with 7 liters of isopropanol, then with 1.5 liters of isopropanol, then three times with 7 liters of ethylene glycol, 1.5 liters of isopropanol and finally 7 liters of iso-propanol. The washed gum is then dried in an oven under reduced pressure at 80 ° C (absolute pressure 66.6 Pa). 1013 g of polymer (ie. 77.4% yield, having the following characteristics: - residual chlorine content: 99 ppm, - viscosity limit value: 77 ml / g - W / light diffusion /: 880,000. Example 4 A suspension containing 16, is prepared in a reactor under nitrogen pressure. 10 g of a 58.5% sodium hydride dispersion in oil. / t. j-. 9,42 g or 0-, 392 mol-pure NaH and 201,30 g -benzene. While keeping the reactor temperature at 4 ° C, the sediment reactor introduces a solution containing 29.40 g (0.294 mol) of trifluoroethanol, 30.53 g (0.151 mol) of alcohol of formula -R H / CF 2 / CH 2 OH and 106.54 g benzene. This addition is carried out within two hours. The reaction mixture is then kept under stirring for a further 4 hours at 4 ° C. 19.72 g of polydichlorophosphazene (ie. 0.340-chlorine equivalent / dissolved in 75.98 g of benzene. This addition is carried out over 10 minutes while maintaining the reactor temperature between 6 and 7 ° C. After 30 minutes, the reaction mixture was allowed to warm to room temperature and a solution containing 1.4 gnonylphenol ethoxylated with 100 molecules of ethylene oxide and 360 g of tetrahydrofuran was added. The reaction mixture was then maintained at 30 ° C for 1.5 hours. The temperature gradually rises to 47 ° C over two hours. The reaction mixture is then left at room temperature for 18 hours.

The mixture was then neutralized by the addition of 1N hydrochloric acid and evaporated to dryness, then dissolved in acetone and filtered to remove sodium chloride. The filtrate is then concentrated to about 70 ml and precipitated with 500 ml of hexane. The precipitate is redissolved twice with acetone, concentrated, and precipitated in hexane, and then dried under reduced pressure (absolute pressure 133 ° C / Pa) at 80 ° C. 47) 45 g (90.7% yield) of polymer having the following characteristics are obtained: residual chlorine content: 222 ppm ppm viscosity limit 65.6 ml / g Mw light diffusion / 1000 000.

Claims (9)

PATENT CLAIMS What is claimed is: 1. A process for preparing polyphosphazenes by substituting polydichlorophosphazene chlorine atoms for nucleophilic reagents in a hydrocarbon medium, wherein the substitution reaction is carried out wholly or partially in the presence of polyether. Process according to claim 1, characterized in that the polyphosphazene contains a plurality of structural units of the general formula I: RN = PIR (1) in which the symbols R, which may be identical or different in one structural unit or in the individual structural units may be an alkyl radical, an aryl radical, an alkoxy radical, a fluoroalkoxy radical, an aryloxy radical, an alkyl sulfide radical, an arylsulfide radical, an alkylamino radical, or an aryl-amine radical. Process according to Claim 1 or 2, characterized in that the nucleophilic agent is selected from the group consisting of compounds of the general formula XR, in which the symbol R is known to occur in the same way as X and X is hydrogen or an alkali metal atom. 4. A process as claimed in any one of claims 2 to 3 wherein the polyether has the general formula: R1R10C Hox 2xR, in which n 'is at least 4, x is 2 or 3 and the symbols are R 1 and X 2, which may be identical or different, may be a hydrogen atom, an alkyl radical containing 1 to 24 carbon atoms, a mono- or polycyclic aryl radical containing up to 18 carbon atoms, or an alkyl-aryl or aralkyl radical whose alkyl and aryl moieties are as above meaning. The method according to claim 4, characterized in that n is greater than 20, and preferably ranges from 50 to 200. Process according to one of the preceding claims 4 or 5, characterized in that one of R 1 and R 8 represents a hydrogen atom and the other one represents an alkylaryl radical containing 8 to 20 carbon atoms. • Φ 4 no. . Process according to one of the preceding claims, characterized in that the polyether is present. is present in the reaction. substitution reaction. Process according to one of the preceding claims, characterized in that the polyether is introduced into the reaction medium during the substitution reaction. 9. A process according to any one of the preceding claims wherein the substitution reaction medium comprises an aromatic hydrocarbon, a cycloaliphatic hydrocarbon or an aliphatic hydrocarbon or a mixture containing several hydrocarbons. Process according to claim 9, characterized in that the substitution reaction medium comprises a mixture of hydrocarbon and ether. Polyphosphazenes obtained by a process according to any one of claims 1 to 10. It is represented by: