Method for preparing n-phosphonomethylglycine

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to a method for preparing N-phosphonomethylglycine. Invention describes a method for preparing N-phosphonomethylglycine from an aqueous mixture containing dissolved N-phosphonomethylglycine, ammonium halides, alkali or earth-alkali metal halides and, optionally, organic impurities. Method involves (a) using a mixture with pH value from 2 to 8; (b) separation of mixture is carried out on a selective nanofiltration membrane, and retentate enriched with N-phosphonomethylglycine and depleted with halides and permeate depleted with N-phosphonomethylglycine are obtained, and (c) N-phosphonomethylglycine is isolated from retentate. Method provides preparing N-phosphonomethylglycine in simultaneous separation of halide salts.

EFFECT: improved preparing method.

13 cl, 5 dwg, 2 tbl, 2 ex

The present invention relates to a method for producing N-phosphonomethylglycine of a mixture, which contains N-phosphonomethylglycine, salt chloride and, optionally, organic pollution. N-phosphonomethylglycine (glyphosphate) is used in a large number of herbicide continuous action. There are many ways to get phosphonomethylglycine. When one of the common ways the last stage is that phosphonomethyliminodiacetic acid or its salt is catalytically oxidized by air, oxygen or hydrogen peroxide. The oxidation is carried out in General in the aquatic environment with the use of coal, salts of molybdenum or vanadium, platinum, rhodium or palladium, etc. as a catalyst. This, along with the N-phosphonomethylglycine formed carbon dioxide or formaldehyde. This method is described in US 3950402 and US 3969398.

As the reaction mixture, and the mother liquor, which is formed after receiving N-phosphonomethylglycine from the reaction mixture by crystallization, contain known carcinogenic formaldehyde. In the document IT 1281094 proposed removal of formaldehyde by using method of separation when using a selective membrane with a pore size in the range from 10 to 1,000 nm. Formaldehyde is separated through product penetration (permeate).

PCT/EP 00/13162 described is no way to obtain N-phosphonomethylglycine, when derived hexahydrotriazine formula Iia

where X means, in particular, CN, is subjected to the interaction with triarylphosphite formula P(OCOR³)₃where R³means, in particular, phenyl, and hydrolyzing the resulting product. N-phosphonomethylglycine receive from the reaction mixture by crystallization at pH value of from 0.5 to 2. The mother liquor has a different composition than the mother liquor obtained in the oxidation phosphonomethyliminodiacetic acid. It contains considerable amounts of N-phosphonomethylglycine, a small number of aminomethyl phosphonic acid, glycine and bis(phosphonomethyl)glycine, as well as large quantities of chloride salts. Desirable is to reduce losses of valuable substances and the reduction of the load on wastewater discharges.

The present invention is to develop a cost-effective method of obtaining N-phosphonomethylglycine from an aqueous mixture which contains dissolved N-phosphonomethylglycine, ammonium salts, salts of alkaline or alkaline earth metals and, optionally, organic pollution. The method should provide for the possibility of a complete receiving N-phosphonomethylglycine and full regeneration contained in the ammonium salts of ammonia.

Unexpectedly, this task is solved in such a way that the aqueous mixture is subjected to separation in the pressure method of separation when using selective nanofiltration membrane.

In accordance with this present invention relates to a method for producing N-phosphonomethylglycine from aqueous mixtures containing dissolved N-phosphonomethylglycine, ammonium halides, the halides of the alkali or alkaline earth metals and, optionally, organic pollution, which

a) the pH value of the mixture set to a value from 2 to 8,

b) separation of the mixture is performed on the selective nanofiltration membrane, and get enriched with N-phosphonomethylglycine and depleted halides product retention (hereinafter permeate) and enriched halides and depleted N-phosphonomethylglycine product penetration (hereinafter retentate) and

in) N-phosphonomethylglycine receive the request from retentate.

The drawings show a stage of the method according to the invention, which show:

1 is a schematic illustration of stage (b) of the method according to the invention a continuous action,

2 is a schematic illustration of stage (b) of the method according to the invention discontinuous steps

Figure 3 schematic illustration of stage (b) of the method according to the invention of figure 1 with the subsequent diafiltration,

Figure 4 schematic illustration of stage (b) of the method according to the invention when run as diafiltration,

Figure 5 schematic illustration of stage (b) of the method according to the invention in a three-stage done the research Institute.

N-phosphonomethylglycine depending on the pH may be in different ionic forms. All these forms are encompassed by the present invention.

When used as a starting material mixture refers to water mixture. It can, if necessary, contain a small proportion, e.g. up to 10 wt.%, mix with water solvent, such as mono - or polisport, such as methanol, ethanol, isopropanol, glycol, 1,2 - or 1,3-propandiol and the like, acetone, dioxane or tetrahydrofuran.

The mixture contains, in terms of weight N-phosphonomethylglycine, excess ammonium halides and halides of the alkali or alkaline earth metals. Under the halides of ammonium, along with NH₄Hal should also understand the halides of ammonium, which is substituted by 1 to 3 C₁-C₄alkyl, or benzyl groups, for example, ammonium methyl halide, dimethyl, trimethyl, tributyl or benzyl. The preferred halides of the alkali or alkaline earth metal halides are sodium, potassium or calcium. As preferred halides, the chlorides. The number of halides is in General at least 8 wt.%, in particular, at least 10 wt.% and particularly preferably at least 12 wt.%, in terms of the total weight of the mixture. The number of N-phosphonomethylglycine is in General Mapecem 4 wt.%, in particular less than 3 wt.%. Preferably, this amount ranges from 0.5 to 3.0 wt.%. According to a preferred form of execution of the mixture occurs from the process of obtaining N-phosphonomethylglycine, which is derived hexahydrotriazine formula II

where X is CN or CONR¹R²and R¹and R²may be the same or different, represent N or C₁-C₄alkyl, are subjected to interaction with triarylphosphines formula III

P(OCOR³)₃

where the residues R³which may be identical or different, denote With₁-C₁₈alkyl or aryl, which optionally may be substituted C₁-C₄the alkyl, NO₂or OS₁-C₄the alkyl and hydrolyzing the resulting product. The interaction may be carried out with a solvent or without solvent. Preferably use an inert organic solvent, in particular, halogenated hydrocarbons such as 1,2-dichloroethane. Acomponent reactions used expediently in stoichiometric quantities. The reaction temperature is generally from -10°to 140°C.

After that, perform acid hydrolysis, and, in particular, are guilty of this halogenation acid as hydrochloric acid. When using hydrochloric acid in COI is lsemaj in the method according to the invention as starting material aqueous mixture contains ammonium chloride.

The acid is used in General in excess, in particular, in the amount of at least 2 equivalents. The temperature at which carry out the hydrolysis, in General, approximately from 10 to 180°C.

Obtained by the hydrolysis with the use of excess acid phosphonomethylglycine dissolved in the aqueous phase. Formed during the hydrolysis of carboxylic acid R³COOH precipitates and can be separated in General the usual way.

Phosphonomethylglycine may be deposited by setting the aqueous phase at a pH value in the range from 0.5 to 2.0 and can be obtained in the usual way. Setting the value of the pH is carried out by addition of a hydroxide of an alkaline or alkaline-earth metal, in particular, the addition of NaOH or KOH.

Remaining after receiving phosphonomethylglycine mixture used as starting material for the method according to the invention. In that case, if it contains an organic solvent, it is removed from the mixture by distillation. The mixture is an aqueous solution mainly with the following composition (in terms of total weight of mixture):

N-phosphonomethylglycine 0.5 to 3 wt.%, in particular 0.5 to 2.5 wt.%,

aminomethylphosphonic acid is 0.01 to 0.5 wt.%,

glycine 0.1 to 0.4 wt.%,

bis(phosphonomethyl)glycine 0.2 to 0.8 wt.%,

the halides of ammonium / alkali halides or alkaline earth metal 10 to 25 wt.%, in particular 12 to 20 wt.%.

SPO is about obtaining N-phosphonomethylglycine through hexahydrotriazine formula II is described in detail in document PCT/EP 00/13162, referenced in this application.

At stage (a) of the method according to the invention the aqueous mixture is set at a pH value of from 2 to 8, in particular from 2.5 to 6.5, and particularly preferably from 4 to 5. This is implemented by the addition of a suitable acid or a suitable base, such as hydrochloric acid, sulfuric acid, phosphoric acid, sodium hydroxide or potassium hydroxide.

At the stage (b) of the method according to the invention the mixture is subjected to separation on the selective nanofiltration membrane. When nanofiltration it is the same as in ultrafiltration and reverse osmosis, driven by the pressure method, membrane separation while applying a positive osmotic pressure on one side of the membrane, which lies above the osmotic pressure that is to be processed solution (osmotic pressure is determined by the retention properties of the membrane). The nanofiltration membrane in General from mechanical considerations applied to single or multi-layer substructure as a carrier of the same material as the membrane or of a different material. The separation layers can be composed of organic polymers, ceramic, metal or carbon. Often used membranes from cross-linked aromatic polyamides. Preferred according to the invention membranes have anionic groups, for example sulfoxylate the e group, and therefore have a negative charge. Suitable membranes nanofiltration known to the person skilled in the art and can be purchased commercially. Examples are prolonged operation-5-membrane system desalinatio company Escondido, USA, NF-membrane company Filmtec Corp., Minneapolis, USA (e.g. NF 70, NF 50, NF 40 NF 40HF), SU 600-membrane company Toray, Japan and NTR-membrane firms Nitto Electric, Japan (e.g., NTR 7450 and NTR 7250-membrane), cf. WO 96/33005.

Preferred according to the invention the membrane have boundaries separating from 50 to 1000 D (Dalton), preferably from 100 to 500 D.

Membrane nanofiltration in practice are embedded in the so-called membrane modules membrane section). This is suitable for all possible shapes (geometry) modules, which are stable under the conditions of the method according to the invention in respect of temperature and pressure. Suitable is, for example, flat, tubular, multi-channel, capillary or roll form. Appropriate forms of execution are available.

The temperature at which stage (b)is not critical. In General, the temperature is chosen in such a way as to prevent damage to the membrane. Therefore, when the polymer membranes of the process is conducted at a temperature of less than 50°C. Ceramic and metallic membranes can also be used at higher temperatures.

Stage (b) is to drive the ' pressure separation. Thus the driving force of membrane separation is a pressure difference of membranes, which must be higher than the osmotic pressure of the applied mixture. An expedient manner, the process is carried out at a transmembrane pressure between the side of retentate and the side of the permeate from 30 to 100 bar.

To prevent concentration polarizations side loading of the membrane and deposition kristallizirovany components bootable solution in General is passed through the membrane in cross-flow (cross flow). Retentate thus, at least partially regenerated. Preferably the process is conducted at a speed bypass boot solution in the range from 0.1 to 5 m/s Speed bypass is focused on the shape of the membrane module and may be easily determined by the expert in this field.

Stage (b) leads to separation of the mixture used to retentate, which is compared to a boot with a solution enriched with N-phosphonomethylglycine, and permeate, which is enriched in ammonium halide, the halide of the alkali or alkaline earth metal. In an unexpected way it provides the possibility of separating the N-phosphonomethylglycine and the above-mentioned halides, although the difference in molecular weight to be separation of components is not very big and N-phosphonomethylglycine quantitatively not present in salt form./p>

Stage (b) of the method according to the invention depending on the desired degree of regeneration of N-phosphonomethylglycine and depending on the desired degree of depletion halides can be implemented in various forms of execution. For example, stage (b) can be conducted as phase concentration at which receive enriched N-phosphonomethylglycine retentate and depleted halides permeate. The degree of depletion of halides on the side of retentate membrane is limited by the osmotic pressure.

In that case, if you want an even greater depletion of the halogen in retentate, to the stage of concentration are connecting at least one stage of diafiltration. For this purpose, to retentate stage concentration add as much water as separate as permeate. Diluted retentate serves then to the stage of diafiltration, which is carried out under the same conditions and with the same membrane as described above. So get depleted halides retentate, which will at one stage concentrate, for example, distillation of the water.

In order to obtain a high depletion halides, stage (b) can be performed as a pure diafiltration. Thus obtained at stage (a) the solution is divided as described above, and in retentate serves as much water as separate as permeate. Get retentate that the La obtain the N-phosphonomethylglycine concentrate, for example, removing water by distillation or reverse osmosis.

As a pure concentration and concentration followed by diafiltration and clean diafiltrate can be single-stage or multistage. With multistep process permeate the previous stage serves connected to the subsequent stage and retentate connected subsequent stage is loaded into the boot solution of the previous stage. At this specific stage can be equipped with the same or different membranes. Multistage process leads to better retention of N-phosphonomethylglycine or its salts.

Obtained after stage (b) retentate can be applied next. Depending on the concentration and purity it may be subjected to concentration or purification or decontamination. In General retentate subjected to further treatment according to stage (I) to receive therein the N-phosphonomethylglycine.

Stage (b) of the method according to the invention is explained below using the drawings:

For the continuous separation of mixtures of figure 1 bootable solution F cross-stream is supplied via line 1 to the membrane module M with the housing 2, in which the membrane 3. Boot solution F flows through the membrane 3, and retentate R is discharged through line 4. Optionally, part of retentate R is recycled through line 5. Permeate R otoliths is on line 6.

Figure 2 shows a discontinuous separation of the boot solution F, which line 1 is the circulation tank 7. The initial liquid level shown in position 8. Boot solution F cross-stream is supplied via line 9 to the above, shown in figure 1 membrane module M On the membrane 3 is divided on retentate that line 4 is supplied to the circulation tank 7, and the permeate is P, which is discharged through line 10. Thus there is a concentration boot solution F, which, finally, as retentate R is discharged through line 10. Available after concentration of the liquid level shown pos.11.

Figure 3 shows the separation of the mixture ratio of the concentration of membrane module M1 and the subsequent steps of diafiltration membrane module M2. The degree of concentration works as described above in connection with figure 1, and line 6 is given permeate P1. Retentate is discharged through line 4, is diluted with water and fed to the degree of diafiltration membrane module M2 housing 12, in which the membrane 13. This membrane works as described in relation to figure 1. Get into retentate R, which is discharged through line 14, having a greater concentration of the permeate P1 and having a lower concentration of the permeate P1, which is discharged through line 15.

Figure 4 explains the carrying out stage (b) in Kutch is TBE net diafiltration. Boot solution F after dilution water is fed by line 1 to the membrane module M and is divided as described above in relation to figure 1.

Figure 5 shows schematically the course of the three-step method. In this method there are three sequentially connected membrane module M1, M2 and M3, which is equipped with a membrane 3. The number of membrane modules can be in any way increased.

Boot solution F cross-flow is fed via line 1 to the first membrane module M1 in the cross flow mode. There is a division on retentate R1 and permeate P1. Retentate R1 is partially removed through line 4 and is partially returned through line 5 into the loading solution. Permeate P1 is supplied via line 6 to the second membrane module M2 in cross flow mode. There is a division on retentate R2 and permeate P2. Retentate R2 is returned to the boot solution F, which line 1 is loaded into the membrane module M1. Optionally, part of retentate R2 is returned to the boot solution membrane module M2. Permeate P2 cross-stream is loaded into the third membrane module MOH. Obtained by dividing retentate R3 supplied in the feed solution membrane module M2. Optionally, part of retentate R3 is returned to the boot solution membrane module M3. Permeate P3 is removed from the process.

To study the (in) of the method according to the invention is the obtaining N-phosphono-methylglycine obtained from stage (b) retentate. To this end, the pH value of retentate is set to a value from 0.5 to 2.0, in particular from 0.8 to 1.5 by addition of acid, for example hydrochloric or sulfuric acid. If necessary retentate concentrate, for example, by distillation or reverse osmosis. It is also possible to add the precipitator to completely precipitate phosphonomethylglycine. As precipitant used is preferably miscible with water, the solvent, such as methanol, ethanol, isopropanol, acetone and other Solvents can be recovered from the mother liquor by distillation and re-used.

Phosphonomethylglycine falls in crystalline form. It can be obtained in the usual way, for example by filtering.

Obtained in stage (b) permeate can be disposed of, or submitted for further processing. Preferably a strong base it is alkalinized, for example, to pH 13-14 to regenerate ammonia, respectively, amine contained in the permeate of the ammonium halides. Suitable bases are hydroxides of alkali or alkaline earth metals such as sodium hydroxide, potassium hydroxide or calcium hydroxide released thus ammonia can be regenerated, for example, by distillation or distillation of the light fractions of inert gas, such as air or nitrogen.

Spasibo the invention, accordingly, each stage separately may be performed continuously, periodically or properities method.

The advantage of the method according to the invention lies in the concentration of N-phosphonomethylglycine, so the product yield is increased. In addition, the achieved separation of components of plant protection from waste waters. And moreover, there is a division contained in the original mixture of chlorides, which allows easy recovery of ammonia from ammonium halides.

The following examples explain the invention without limiting it.

Example 1

In a two-liter flask with a Teflon paddle stirrer and reflux condenser load of 284 g of the benzoate of ammonia in 1000 ml of 1,2-dichloroethane and in nitrogen atmosphere for 30 minutes was added dropwise 91,5 g trichloride phosphorus. The temperature is increased up to a maximum of 36°C. Then the reaction mixture is stirred for 30 minutes at a temperature of from 25 to 36°C. the Mixture is filtered through a pressure suction filter and the filter residue in the atmosphere of nitrogen washed twice each time through 500 g of dichloroethane (2054 g of the filtrate).

The filtrate is loaded into a two-liter flask with a Teflon paddle stirrer and reflux condenser at room temperature and add hexahydrotriazine IIa (X=CN) (45,54 g). When mixing reaction the second mixture is heated for 30 minutes to 80° C and stirred for another 30 minutes. The solution is allowed to cool and immediately after that it hydrolyzing, for which the original substance is metered into the tubular reactor (volume approx. 600 ml) upstream of the static mixer at 130°and 8 bar (1265 g/h of a solution of dichloroethane with the previous stage, 207 g/h 20%HCl). The residence time in the reactor is 30 minutes. The first fraction is removed from the process. For further processing the resulting two-phase mixture are collected within 60 minutes. The phases are separated at 60°and the aqueous phase is twice extracted with the use of 100 g of dichloroethane.

In a round flask with a Teflon paddle stirrer, first remove contained in the aqueous phase dichloroethane by feeding within 1 hour of nitrogen at 60°C. and Then for 15 minutes to set the pH value of 1.0 using 50%aqueous sodium sulfite liquor at a temperature of from 40 to 60°C. the resulting suspension is stirred for another 3 hours at 40°C, cooled to room temperature, sucked off the precipitated product, and then washed with 150 g of ice water. The obtained solid is dried at 70°C and 50 mbar for 16 hours.

Output: 54.6 g of phosphonomethylglycine (purity of 96.2% SGH), respectively, 80% of the output in terms of PCl₃.

The mother liquor of crystallization has the following composition, wt.%:

The pH value of mother liquor install, then with 50%NaOH to a value of 4. The mother liquor is then periodically concentrate in working under pressure cell with a stirrer. This cell is equipped with a nanofiltration membrane type prolonged operation 5 DK firms prolonged operation-Osmotics. Nanofiltration is carried out at a temperature of 40°and a pressure of 80 bar. The average integral flux of permeate is of 5.29 kg/m²including Get hold of N-phosphonomethylglycine in 99,22% and the depletion of chloride salts in 86,26%. The results are presented in the following table 1.

To obtain the N-phosphonomethylglycine in a round flask with a volume of 250 ml with Teflon paddle stirrer serves 50.0 g of retentate and 30.0 g of water. Within 10 minutes was added dropwise at 40°14.24 from g of 20%HCl to achieve a pH of 1.3. The resulting suspension is stirred for 3 hours at 40°and then allowed to cool to room temperature. Fallen phosphonomethylglycine sucked off and washed with 20 g of water. The solid is dried at 70°C and 50 mbar for 16 hours.

Output: 4,10 g solids (containing 94.7% of phosphonomethylglycine that corresponds to the degree of regeneration 53%)

Analysis: NaCl 0,0%; phosphonomethylglycine 94,7% (SGH).

The mother solution: 106,8 g of the solution.

Example 2

Periodic two-stage concentration obtained according to example 1 mother liquor.

The pH value of mother liquor install as described in example 1 to size 4. The mother liquor is periodically concentrate in working under pressure is the cell with the mixer described in example 1; i.e. having the same membrane. The process conditions are the same as in example 1. The permeate is served in additional pressure cell with a mixer of the same type and concentrate. Concentration is carried out at 40°C and 40 bar. Average specific flux of the permeate of the second stage is 25,70 kg/m²hours Calculated in two steps retention of N-phosphonomethylglycine is about 99.99% and the depletion of salts of chloride, about 77,82%. The results are shown in table 2.

1. The method of obtaining N-phosphonomethylglycine from aqueous mixtures containing dissolved N-phosphonomethylglycine, ammonium halides, the halides of the alkali or alkaline earth metals and, optionally, organic pollution, which

a) the pH value of the mixture set to a value from 2 to 8,

b) separation of the mixture is performed on the selective nanofiltration membrane, and get enriched with N-phosphonomethylglycine and depleted halides retentate and enriched halides and depleted N-phosphonomethylglycine permeate and

in) N-phosphonomethylglycine distinguish from retentate.

2. The method according to claim 1, wherein the mixture comes from the process of obtaining N-phosphonomethylglycine, in which the triazine of the formula II

where X denotes a CN, or CONR¹R²and R¹and R²may be the same or different and denote H or C₁-C₄-alkyl,

subjected to interaction with triarylphosphite formula (III)

P(OCOR³)₃,

where the residues R³mean₁-C₁₈alkyl or aryl, which is not necessarily Sames the h ₁-C₄the alkyl, NO₂or OS₁-C₄the alkyl,

and hydrolyzing the resulting product halogen acid.

3. The method according to claim 2, in which the applied mixture, which is obtained as the mother liquor interaction triazine of the formula II with triarylphosphite formula III, obtained by hydrolysis product hydrochloric acid and separation of N-phosphonomethylglycine when the pH value is from 0.5 to 2.

4. The method according to claim 3, wherein the mixture contains from 0.5 to 3 wt.% N-phosphonomethylglycine and from 10 to 25 wt.% chloride salts.

5. The method according to claim 1, wherein the pH value of the mixture set to a value in the range from 2.5 to 6.5.

6. The method according to claim 1, wherein in stage (b) using a membrane with boundary separation in the range from 50 to 1000 D.

7. The method according to claim 6, wherein in stage (b) using a membrane with boundary separation in the range from 50 to 1000 D.

8. The method according to claim 1, wherein the separation of the mixture in stage (b) is carried out at a transmembrane pressure between the side of retentate and permeate side in the range from 30 to 100 bar.

9. The method according to claim 1, wherein the separation of the mixture in stage (b) is carried out at a feed rate in the range of from 0.1 to 5 m/S.

10. The method according to claim 1, wherein the separation of the mixture in stage (b) carry out multi-stage, and permeate one level serves a subsequent stage as zagruzochnogo the solution.

11. The method according to claim 10, wherein retentate the second, respectively the next stage, at least partially, served on the first, respectively the previous step.

12. The method according to claim 1, in which obtained in stage (b) retentate is subjected to at least one level of diafiltration.

13. The method according to claim 1, in which the permeate is treated with a strong base and release contained in the ammonium halides ammonia, respectively Amin.