HRP940732A2 - Process for the preparation of sulfonated aryl phosphines - Google Patents

Description

The technical field to which the invention belongs

The invention belongs to the field of organic chemical synthesis.

Technical problem

This invention relates to a process for the preparation of pure sulfonated arylphosphines.

State of the art

The production of sulfonated phenylphosphines is known. Thus, the sodium salt of m-sulfophenyl-diphenyl-phosphine is obtained by reacting triphenylphosphine with oleum, heating the reaction mixture in a water bath, diluting the reaction product with water and neutralizing it with sodium hydroxide. The desired compound then crystallizes from the mixture (J. Chem. Soc. 1958, pages 281, 282).

The sodium salts of di(m-sulfophenyl) phenylphosphine and tri(m-sulfophenyl)-phosphine are also obtained by a similar process. The material used in both cases is again triphenylphosphine, which reacts with oleum at temperatures between 18 and 40°C in a time interval of 15 to 63 hours. The reaction product is also diluted with water and neutralized with sodium hydroxide, where care should be taken to maintain the temperature below 20°C during the addition of sodium hydroxide to the mixture (DE-PS 26 27 354).

By treating sodium salts with a cationic ion exchange resin, free acids are obtained, which can react with different bases to form other salts. In this way, for example, the barium salt and the tetraethylammonium salt of tri(sulfophenyl)phosphine (DE-PS 26 27 354) can be produced.

The disadvantage of known processes for the production of sulfonated arylphosphines is the formation of numerous by-products, especially of different degrees of sulfonation of arylphosphines, arylphosphine oxides, and arylphosphinsulides. Obtaining pure compounds can only be achieved through painstaking purification operations that have high losses.

Among other things, sulfonated arylphosphines are used as compositions of catalyst systems. For these, but also other purposes of application, it is necessary to have available pure material, i.e. homogeneous products of sulfonation, which, in addition, are free of further impurities, which are produced as side products during production, such as sulfonated arylphosphine oxides and arylphosphine sulfides or which can be produced during production into the reaction mixture, such as chloride ions and iron ions.

For this reason, there was a task to develop a process for the production of sulfonated arylphosphines that do not have the disadvantages of known processes and that lead in a simple way to pure substances without the use of working steps that have large losses.

Description of the solution to the technical problem with implementation examples

According to the invention, this goal is achieved by a process for producing mono-, di- or trisubstituted phosphines by sulfonating triarylphosphine with oleum at 0 to 40 °C and diluting the sulfonation mixture with water.

It is indicated by the fact that the aqueous solution is extracted with an amine solution not dissolved in water into an organic solvent not dissolved in water, whereby 0.5 to 1.5 moles of amine is applied per equivalent of sulfonic acid, the organic phase is separated, brought into contact with good mixing with with an aqueous solution of the base, after that the aqueous phase is separated and the sulfonated arylphosphine is isolated from it.

The new way of working allows not only to free the salts of sulfonated arylphosphines from impurities, which reach the reaction product during the production process, but also to remove by-products and to enrich arylphosphines of different degrees of sulfonation and finally separate them from each other.

The procedure for separating water-dissolved salts of aromatic sulfonic acids is described in EP-A 00 41 134. In this case, the water-diluted sulfonation mixture is treated with an amount of such amine that is not dissolved in water that is equivalent to the sulfonated acid, which forms a lipophilic salt with the sulfonic acid.

After that, the two formed phases are separated and the phase containing the ammonium salt is treated with a stoichiometric amount of base dissolved in water, whose sulfonic acid is to be produced. A sulfonic acid salt is obtained in an aqueous solution, which can be isolated. This procedure assumes that the ammonium salt is liquid below the boiling point of aqueous sulfuric acid.

In addition, the sulfonates that need to be processed do not contain by-products of the phosphinoskid or phosphine sulfide type, which have a very similar constitution to the desired compounds, so they show barely different physical behavior, but still must be separated completely. The new process can generally be applied to mono-, di- and trisubstituted arylphosphines or their mixtures, i.e. especially phosphines, which have phenyl or naphthyl residues and which in a given case may also contain alkyl residues.

The procedure according to the invention is performed as follows:

While maintaining a temperature between 0 and 90°C, especially 20 and 40°C, the sulfonation mixture is mixed with as much water as is necessary to dilute the present sulfuric acid to 0.5 to 50 wt. %, primarily 25 to 35 wt. %. A water-insoluble amine dissolved in a water-insoluble organic solvent is added to the diluted solution. The concentration of the amine solution is 0.5 to 35 wt. %, primarily 10 to 30 wt. %, and especially 15 to 25 wt. % amine.

0.5 to 1.5 mol preferably 0.8 to 1.2 mol of amine is applied per equivalent of sulfonic acid. The use of excess amine certainly ensures that only minor yield losses occur. A greater excess applied than the excess according to the invention is indeed possible, but it does not lead to an improvement in the results of the work of separation or purification or yield.

After intense mixing, two phases are formed. Specific heavier, aqueous phase acid, organic phase containing little sulfate amine salt of sulfonic acid dissolved in organic solvent (salt phase). The salt phase is separated.

At the end, the salt phase reacts with a base solution in water, whose sulfonic acid is to be made. The base is used in an amount equivalent to the dissolved amount of the amine salt. Excess base contaminates the final product. Thus, with the recovery of the amine undissolved in water, an aqueous solution of the desired sulfonic acid salt is obtained. Amine is available for reuse.

The process according to the invention can be performed discontinuously or continuously. Conventional devices such as extraction plants in the opposite flow are used for the separation of substances.

Instead of adding a base dissolved in water all at once to a solution of an amine salt in an organic medium, according to the embodiment of the process according to the invention, which is supposed to be added in portions, it can be done. This mode of operation is used with success, especially when trying to separate the sulfonation mixture, which contains products of different degrees of sulfonation. The number of reextraction phases, i.e. the conversion of sulfonic acid as an amine salt dissolved in an organic medium into an aqueous medium by treatment with an aqueous base solution, should be adapted to the composition of the reaction mixture. In general, it is sufficient to completely adapt to the composition of the reaction mixture. In general, it is quite sufficient to perform two out of five times of re-extraction to obtain pure sulfonic acids. It is expedient to add a base dissolved in water to the organic phase until a certain pH value is reached, then the phases are separated from each other, the addition of the base continues until the pH values are set to higher and the aqueous solution is treated separately.

As water-insoluble amines, which according to the invention are used for carrying out the new process, water-insoluble homo- and heterocyclic, aliphatic, aromatic, araliphatic and primarily open-chain, branched or unbranched aliphatic amines with 10 to 60, primarily with 13 come into consideration. up to 36 carbon atoms. Less suitable are amines, whose salts with sulfonic acids are undissolved or only partially dissolved in the organic solvent. Examples of particularly suitable amines include: tri-n-octylamine, tri-isooctylamine, tri-2-ethylhexylamine, methyl-di-octylamine, tridodecylamine.

Amines are dissolved in an organic solvent insoluble in water.

Particularly suitable are aliphatic or aromatic hydrocarbons or mixtures of hydrocarbons, for example toluene or fractions similar to kerosene, in addition also C4-C20-alcohols, C8-C20-ethers.

Alkali and alkaline earth metal hydroxides, especially alkaline hydroxide, ammonia, and also alkaline carbonates are suitable as bases for converting sulfonic acid phosphines into the aqueous phase and at the same time into the desired salt as the final product. But amines dissolved in water can also be used, such as methylamine, ethylamine, propylamine, butylamine or ethanolamine.

The procedure is performed at room temperature. Higher temperatures do not provide an advantage. Data on the solubility of amines and organic solvents in water always refer to the temperatures at which the procedure was performed.

The final product is either left in aqueous solution or obtained in solid form by evaporation or crystallization, decantation and filtration.

By means of the following examples, the invention is explained in more detail, but is not limited in its scope of protection.

Example 1

Production of TPPDS as well as extraction of the sulfonation mixture

960 g of 30% eluent (D = 1.94) is placed in a 1-liter reaction vessel equipped with a stirrer, thermometer, addition funnel and refrigerator and cooled under nitrogen at an internal temperature of 15°C. Then, over the course of 2 hours, 105 g (0.4 mol) of triphenylphosphine and another 320 g of 30% eluent are added with stirring and the reaction temperature is maintained between 15 and 20°C. After the addition is complete, the reaction mixture is stirred for another 3.5 hours at 20°C.

The contents of the reaction vessel are then poured under nitrogen protection into a 6-liter reaction vessel containing 2505 g of water at approximately 10°C. During the addition, the internal temperature is maintained between 20 and 40°C by intensive cooling. The reaction solution has the following composition (m = 3890 g):

Table 1

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(In the previous and following Tables, the abbreviations used mean:

TPPMS : triphenylphosphine monosulfonic acid sol

DS : triphenylphosphindisulfonic acid salt

TS : triphenylphosphine trisulfonic acid salt

OMS: triphenylphosphine oxide monosulfonic acid salt

ODS: triphenylphosphinoxyldisulfonic acid salt

OTS: triphenylphosphine oxide trisulfonic acid salt

SDS: triphenylphosphine sulfide disulfonic acid salt

STS: triphenylphosphine sulfide trisulfonic acid salt)

The homogeneous sulfonated mixture of the above composition is placed in a 6-liter reaction vessel under nitrogen and mixed with stirring with a mixture of 303 g (858 mmol) of triisooctylamine and 1212 g of toluene. After the addition is complete, it is stirred for another 30 minutes and left to settle for 30 minutes. The lower phase (3665 g of aqueous sulfuric acid) was separated and discarded.

The organic phase (1731 g) has the following composition:

Table 2

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The organic phase contains 1.3 wt. % sulfate.

Example 2

Production of TPPTS as well as extraction of the sulfonation mixture

According to Example 1, 960 g of 30% oleum is placed in a 1-liter reaction vessel. In the course of 2 hours, 105 g (0.4 mol) of triphenylphosphine and another 320 g of 30% oleum are added. After that, it is stirred for 24 hours at 20°C.

The reaction mixture is then poured into 2502 g of water at 10°C, 3887 g of the sulfonation mixture with the following composition is obtained

Table 3

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The homogeneous sulfonation mixture of the above composition is mixed according to Example 1 with a mixture of 388 g (1099 mmol) of trizooctylamine and 1552 g of toluene. After separating the phases, 3660 g of an aqueous solution of sulfuric acid and 2167 g of an organic phase with the following composition are obtained:

Table 4

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The sulfate concentration in the organic phase is 1.44 wt. %.

Example 3

Re-extraction of the TPPDS-containing amine extraction solution using dilute potash at 20°C

According to example 1, a sulfonation mixture is prepared which mainly contains TPPDS and is extracted using a solution of triisooctylamine and toluene. The organic solution (3000 g) has the following composition:

Table 5

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The sulfate concentration is 1.4%.

The extraction product is then mixed in a 6-liter reaction vessel with stirring and nitrogen protection gradually with 5% aqueous potassium lye. pH measurement is done using a glass electrode common in the store. When the desired pH value is reached, the addition of potassium alkali is stopped. The two-phase system formed from triisooctylamine, toluene and potassium salts of sulfonated triphenylphosphine as well as the corresponding oxides and sulfides is separated, and the anhydrous organic phase is mixed again with aqueous potassium alkali. The organic phase is either discarded or reused to extract the sulfonation mixture.

The composition of aqueous solutions of potassium salts is listed in the following Tables.

Table 6

S a s t a v

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Samples 8 and 9 have a DS content of 91.3 and 92.5 wt. %. By evaporating aqueous solutions until the beginning of crystallization, filtering, washing with methanol and drying, the potassium salt of di(m-sulfophenyl)phenylphosphine can be obtained as a white solid with >95% purity.

Example 4

Re-extraction with dilute potassium hydroxide at 20°C of the amine extraction solution containing TPPTS

According to Example 2, a sulfonation mixture containing predominantly TPPTS is prepared and extracted using a toluene solution of triisooctylamine. The thus obtained organic phase (1926) has the following composition:

Table 7

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The sulfate concentration in the organic phase is 1.52 wt. %.

Re-extraction with the help of 5% potassium lye is performed according to Example 3 at an internal temperature of 20°C. The results are listed in the following table:

Table 8

S a s t a v

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Samples 5 and 6 have a TS content of 90.6 and 91.8 wt. %. By evaporating aqueous solutions until the beginning of crystallization, filtering, washing with methanol and drying, the potassium salt of tri(m-sulfenyl)phosphine can be obtained as a white solid with a purity of < 95%.

Example 5

Influence of the amount of amine during the extraction of the sulfonation mixture containing TPPDS

The sulfonation mixture prepared according to Example 1 is extracted with different amounts of triisooctylamine and toluene in the manner specified in Example 1.

The mixture for sulfonation /432 g/ has the following composition:

Table 9

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The sulfuric acid extraction of the solution is performed while maintaining the same temperature, constant composition of the sulfonation mixture and the same duration of extraction; the following results are obtained:

Table 10

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The composition of organic amine extraction solutions is listed in the following Table:

Table 11

Organic phase

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1/ extracted sulfonates calculated on total sulfonates taken /in wt. %/

2/ extracted DS calculated on the amount of DS taken /in wt. %/

3/ extracted TS calculated on the amount of TS taken /in wt. %/

Table 11 /continued/

Organic phase

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1/ extracted sulfonates calculated on total sulfonates taken /in wt. %/

2/ extracted DS calculated on the amount of DS taken /in wt. %/

3/ extracted TS calculated on the amount of TS taken /in wt. %/

Example 6

Influence of the amount of amine during the extraction of the sulfonation mixture containing TPPTS

The sulfonation mixture prepared according to Example 2, which mainly contains TPPTS, is extracted with different amounts of triisooctylamine and toluene in the manner specified in Example 5.

Sulfonation mixture /3911/ has the following composition:

Table 12

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The extraction of the sulfuric acid solution is performed at 20°C, with a constant composition of the sulfonation mixture and the same duration of extraction; the results are compiled in the following Table.

Table 13

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The organic phase is re-extracted according to Example 3 with appropriate amounts of aqueous 7.1% potassium lye. The compositions of the potassium salt solutions thus obtained are listed in the following table:

Table 14

Aqueous solution of potassium salt

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1) extracted sulfonates calculated on total sulfonates taken /in weight. %/

2) extracted DS calculated on the amount of DS taken /in wt. %/

3) extracted TS calculated on the amount of TS taken /in wt. %/.

Table 14 /continued/

Organic phase

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1) extracted sulfonates calculated on total sulfonates taken /in wt. %/

2) extracted DS calculated on the amount of DS taken /in wt. %/

3) extracted TS calculated on the amount of TS taken /in wt. %/

Example 7

Dependence on the type of amine

The sulfonation mixture prepared according to example 1 is extracted in the usual way with different amine-toluene mixtures. The composition of the sulfonation mixture used as well as the extraction results found are summarized in the following Tables:

Table 15

Composition of sulfonation mixture /500 g/

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Table 16

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Table 17

[image] 1/ During the extraction, three phases are formed, where the upper phase contained another 0.32% (= 1 mMol/

DS, the middle phase contained the main amount of valuable product

Claims (6)

1. Process for producing mono-, di- or trisulfonized arylphosphines by sulfonating triarylphosphines using oleum at 0 to 40°C and diluting the sulfonation mixture with water, characterized in that the aqueous solution is extracted using a solution of an amine insoluble in water in an organic solvent insoluble in water, whereby 0.5 to 1.5 mol of amine is applied per sulfonic acid equivalent, the organic phase is separated, mixed well with an aqueous base solution, after which the aqueous phase is separated and the sulfonated arylphosphine is isolated from it. 2. The method according to claim 1, characterized in that 0.8 to 1.2 moles of amine are applied per equivalent of sulfonic acid. 3. The method according to claim 1 and 2, indicated by the fact that open chain amines, branched or unbranched with 10 to 60 carbon atoms, preferably 13 to 36 carbon atoms, are used. 4. The method according to claim 1 to 3, characterized in that toluene or hydrocarbon fractions similar to kerosene are used as the solvent for the amine. 5. Process according to claim 1 to 4, characterized in that alkali hydroxides, ammonia or alkali carbonates are used as bases. 6. The method according to claims 1 to 5, characterized in that the addition of the base dissolved in water is done in parts and after each addition of the base in parts, the aqueous phase is separated.