Process for making mixtures of enantiomers of MGDA and GLDA

Abstract

Process for preparation of a mixture of methyl glycine diacetic acid (MGDA) or its respective mono-, di-, trialkali metal salt or its respective mono-, di- or tri-ammonium salt or mixtures thereof, and glutamic acid diacetic acid (GLDA) or its respective mono-, di-, tri-, or tetra-alkali metal or mono-, di-, tri- or tetra-ammonium salt or mixtures thereof, wherein said process com-prises the steps of: (a) dissolution in water of (a1) alanine in its L- or D-enantiomeric form or its respective monoalkali metal salt or mixtures thereof, and (a2) glutamic acid as L- or D-enantiomer or its respective mono-, or dialkali metal or mixtures thereof, wherein the molar ratio of alanine to glutamic acid is in the range of from 1:9 to 9:1, (b) converting the mixture obtained in step (a) with formaldehyde and hydrocyanic acid or alkali metal cyanide to the corresponding dinitriles, (c) saponification of the dinitriles resulting from step (b).

Claims

1. A process for preparing a composition comprising methyl glycine diacetic acid (MGDA) or its respective mono-, di-, trialkali metal salt or its respective mono-, di- or tri-ammonium salt or mixtures thereof, and glutamic acid diacetic acid (GLDA) or its respective mono-, di-, tri-, or tetra-alkali metal or mono-, di-, tri- or tetra-ammonium salt or mixtures thereof, the process comprising: (a) dissolving in water (a1) alanine in its L- or D-enantiomeric form or its respective monoalkali metal salt or mixtures thereof, and (a2) glutamic acid as L- or D-enantiomer or its respective mono-, or dialkali metal or mixtures thereof, wherein a molar ratio (a1) to (a2) of alanine to glutamic acid is in the range of from 1:9 to 9:1, to obtain a mixture; (b) converting the mixture with formaldehyde and hydrocyanic acid or alkali metal cyanide to dinitriles; and (c) saponifying the dinitriles, to obtain the composition.

2. The process according to claim 1, wherein the saponifying (c) is carried out in two steps (c1) and (c2) at different temperatures.

3. The process according to claim 1, wherein the saponifying (c) is carried out by employing stoichiometric amounts of hydroxide or an excess of 1.01 to 1.5 moles of hydroxide per molar sum of COOH groups and nitrile groups in the converting (b).

4. The process according to claim 1, wherein a solids content of the composition is in the range of from 40 to 70% by weight.

5. The process according to claim 1, wherein the molar ratio of (a1) to (a2) is in the range of from 2.5: 7.5 to 7.5: 2.5.

6. The process according to claim 1, wherein the composition comprises a mixture of L- and D- enantiomers of MGDA or its respective mono-, di- or tri-alkali metal or mono-, di- or tri-ammonium salt or mixtures thereof comprising predominantly the respective L-isomer with an enantiomeric excess (ee) in the range of from 10 to 95%, and L- and D-enantiomers of GLDA or its respective mono-, di-, tri-, or tetra-alkali metal or mono-, di-, tri- or tetra-ammonium salt or mixtures thereof.

7. The process according to claim 1, wherein the saponification (c) is carried out with sodium hydroxide or potassium hydroxide.

8. The process according to claim 1, wherein the converting (b) is carried out at a temperature in the range of 10 to 45 C.

9. The process s according to claim 2, wherein the saponifying (c1) is carried out at a temperature in the range of from 10 to 80 C., and the saponifying (c2) is carried out at a temperature in the range of from 90 to 195 C.

10. The process according to claim 2, wherein the saponifying (c2) has an average residence time in the range of from 15 to 360 minutes.

11. A composition, comprising L- and D- enantiomers of MGDA or its respective mono-, di- or tri-alkali metal or mono-, di- or tri-ammonium salt or mixtures thereof containing predominantly the respective L-isomer with an enantiomeric excess (ee) in the range of from 10 to 95%, and L- and D-enantiomers of GLDA or its respective mono-, di-, tri-, or tetra-alkali metal or mono-, di-, tri- or tetra-ammonium salt or mixtures thereof, wherein: the composition does not contain an organic polymer; and the composition does not contain a surfactant.

12. The composition according to claim 11, wherein a molar ratio of MGDA to GLDA or their respective salts is in the range of from 1:9 to 9:1.

13. An aqueous solution, comprising the composition of claim 11, wherein the aqueous solution has a solids content in the range of from 40 to 70% by weight.

14. A solution, comprising MGDA and GLDA, wherein the solution is obtained from a composition formed by the process of claim 1.

15. A composition formed from the aqueous solution of claim 13, said composition being a laundry detergent composition or a detergent composition for cleaners.

Description

WORKING EXAMPLES

(1) General Remarks:

(2) The ee values of MGDA were determined by HPLC using a Chirex 3126 column; (D)-penicillamine, 5 m, 2504.6 mm. The mobile phase (eluent) was 0.5 mM aqueous CuSO4-solution. Injection: 10 l, flow: 1.5 ml/min. Detection by UV light at 254 nm. Temperature: 20 C. Running time was 25 min. The ee value was determined as difference of the area % of the L- and D-MGDA peak divided by the sum of area % of L- and D-MGDA peak. Sample preparation: A 10 ml measuring flask was charged with 5 mg of test material and then filled mark with the eluent and then homogenized.

(3) Specific rotation was determined at 20 C., wavelength 589 nm, with a modular circular polarimeter MCP 300, Fa. Anton Paar GmbH.

(4) Viscosities have been measured using a Brookfield viscometer measuring the samples at 23 C. with spindle 31.

(5) Optical appearance has been measured 24 hours after preparation of the aqueous solution, which was stored at 23 C. in a closed bottle.

(6) The following substances were used:

(7) GLDA-Na.sub.4 (Dissolvine GL-47 ST, AkzoNobel Functional Chemicals BV, 47% by weight aqueous solution). The ee of Dissolvine GL-47 ST is 95%. Specific rotation of Dissolvine GL-47 S is 6.9 deg ml g.sup.1 dm.sup.1.

(8) The ee values are given in mol-%. All other percentages refer to weight percentages unless specified otherwise.

EXAMPLE 1.1

(9) Synthesis of a Solution of Partially Neutralized L-alanine bis-acetonitrile (ABAN) and L-glutamic Acid amino diacetonitrile sodium Salts (GLDN), Steps (a.1) and (b.1)

(10) Step (a.1): A 1-litre stirred flask was charged at room temperature with 136 g of de-ionized water. 66.88 g of L-alanine (99%, 0.74 mole) were added. To the resultant slurry 39 g of 50% by weight aqueous sodium hydroxide solution (0.49 mole) and 108.62 (99%, 0.57 mole) L-monosodium-glutamate monohydrate were added. After complete addition the slurry was stirred at 50 C for 30 minutes. A clear solution was obtained.

(11) Step (b.1): A 1.5-litre stirred flask was charged with 100 ml of water at room temperature. Then, 350 g of the amino acid solution (1.31 mole) according to step (a.1), 275.4 g of 30% by weight aqueous formaldehyde solution (2.09 mole) and 58.9 g of hydrogen cyanide (99%, 2.17 mole) were added simultaneously at 18 to 20 C. within 60 minutes. The resulting solution was then simultaneously added to a 1.5-litre flask together with additional 14.9 g of hydrogen cyanide (99%, 0.54 mole) at 18 to 20 C. within 60 minutes. Upon completion of the addition the reaction mixture was stirred for additional 30 minutes at 20 C. A solution was obtained that contained partially neutralized L-alanine bis-acetonitrile (ABAN) and L-glutamic acid amino diacetonitrile (GLDN) sodium salt.

EXAMPLE 1.2

(12) Syntheses of an Aqueous Solution of MGDA-Na.sub.3 and GLDA-Na.sub.4 (c1.1) and (c2.1)

(13) Step (c1.1): A 1.5-litre stirred flask was charged with 100 ml of water and 29.2 g of 50% by weight aqueous sodium hydroxide solution (0.37 moles) and heated to 30 C. Then, simultaneously 900 g of the solution of partially neutralized ABAN and GLDN of Example 1 and 263 g of 50% by weight aqueous sodium hydroxide solution (3.29 moles) were added dropwise. An exothermic reaction could be observed. The reaction mixture was stirred for 2 hours. Step (c2.1): The reaction mixture obtained according to (c1.1) was stirred at 80-90 C. for 6 hours. The color of the reaction mixture turned to light yellow. The NH.sub.3 formed during the reaction was continuously removed by stripping. The volume of the reaction mixture was kept constant by repeated addition of water.

(14) A 40% solution of MGDA-Na.sub.3 and GLDA-Na.sub.4 was so obtained. The overall yield was 96%, determined by titration of Fe(III+) in the form of FeCl.sub.3 in aqueous solution. The individual yields were 96% MGDA-Na.sub.3 (ee>96%) and 92% GLDA-Na.sub.4 (ee>96%) with 0.06% nitrilotriacetic acid (NTA)-Na.sub.3 and 0.30% glutamic acid N-monoacetic acid (GLMA)-Na.sub.3 as determined by HPLC analysis.

(15) The resulting aqueous solution was concentrated to 57% by weight and stable at least for 3 months.

Example 2

(16) Step (a.2) was performed in accordance with step (a.1) in Example 1.1.

(17) The continuous syntheses of ca. 40% solutions of inventive solutions were carried out in cascade of 6 stirred tank reactors, total volume of 8.5 l. The reaction mixture passed all 6 stirred tank reactors (STR.1 to STR.6) consecutively. The last stirred tank reactor to be passed, STR.6, was connected to a tubular reactor, TR.7. In the first three stirred tank reactors, STR.1 to STR.3, partially neutralized mixture of ABAN and GLDN were synthesized, and STR.1 to STR.3 were operated at 20 C. The average residence time in STR.1 to STR.3 was 45 to 90 min in total. In the three stirred tank reactors STR.4 to STR.6 the saponification was carried out. STR.4 to STR.6 were operated at 60 C. The average residence time in STR.4 to STR.6 was 170 to 400 min in total. The saponification was then completed in tubular reactor TR.7 which was operated with a temperature of 180 C. The pressure in TR.7 was 22 bar, and the residence time was 31 minutes. The final ammonia stripping was done in a column under normal pressure using steam. Formaldehyde (30% aqueous solution), an aqueous solution of L-alanine (I) and its sodium salt, L-Glutamate obtained according to 1, step (a.2), and 80 mole-% of the required HCN were added to STR.1, the remaining 20% of the required HCN were added to STR.2, the required sodium hydroxide solution was added in STR.4.

(18) The molar ratios of the feed materials were as follows:

(19) L-alanine and the alkali metal salt: 0.56, L-Na-glutamate: 0.44

(20) Formaldehyde=1.95 to 2.07,

(21) HCN=1.95 to 2.10 and

(22) Sodium hydroxide=3.15 (including sodium hydroxide added in step (a.2).

(23) A 40% solution of MGDA-Na.sub.3 and GLDA-Na.sub.4 was so obtained. The overall yield was 95%, determined by titration of Fe(III+) in the form of FeCl.sub.3 in aqueous solution. NTA-Na.sub.3 was 0.04% and 0.30% GLMA-Na.sub.3 as determined by HPLC analysis.

EXAMPLES 3 to 6

(24) Examples 3 to 6 were carried out as described in Examples 1.1 and 1.2. Table 1 summarizes raw materials and process parameters applied. Table 2 summarizes yield and by products.

(25) TABLE-US-00001 TABLE 1 Raw materials and process parameters for the manufacture of solutions of MGDA-Na.sub.3 and GLDA-Na.sub.4 according to Examples 1.1 and 1.2. Step (b) Concentrations (Raw materials: L-monosodium glutamate monohydrate, Step (b) L-alanine (65% neutralized Step (b) Step (c1) Steps (c1) and (c2) # Temperature with NaOH) Dosage NaOH Saponification Example 3 19-20 C. 30% by weight 1) HCN (2.17 moles) and formaldehyde 3.66 moles Step (c1.3) (0.74 moles alaninate, (2.73 moles) within 60 min. Dosage of NaOH: 1 h/28-32 C. 0.57 moles glutamate) 2) HCN (0.54 moles) within 60 min After-reaction: 1 h/31-35 C. 3) stirring for 30 min at 19-20 C. Step (c2.3) 6.5 h/98-100 C. Example 4 19-21 C. 45% by weight 1) HCN (2.17 moles) and formaldehyde 3.66 moles Step (c1.4) (0.74 moles alaninate, (2.73 moles) within 60 min. Dosage of NaOH: 1 h/30 C. 0.57 moles glutamate) 2) HCN (0.54 moles) within 60 min After-reaction: 1 h/30 C. 3) stirring for 30 min at 20 C. Step (c2.4) 7.5 h/92-96 C. Example 5 18-23 C. 50% by weight 1) HCN (2.17 moles) and formaldehyde 3.74 moles Step (c1.5) (0.74 moles alaninate, (2.75 moles) within 60 min. Dosage of NaOH: 1 h/22-32 C. 0.57 moles glutamate) 2) HCN (0.54 moles) within 60 min After-reaction: 1.5 h/30 C. 3) stirring for 30 min at 20 C. Step (c2.5) 5.5 h/80-92 C. Example 6 35-40 C. 30% by weight 1) Formaldehyde (2.70 moles) within 15 min 4.03 moles Step (c1.6) (0.74 moles alaninate, 2) HCN (2.15 moles) within 30 min at 30 C. Dosage of NaOH: 1 h/40-57 C. 0.57 moles glutamate) 3) HCN (0.54 moles) within 30 min at 40 C. After-reaction: 1 h/40 C. 4) stirring for 60 min at 40 C. Step (c2.6) 10 h/90-93 C.

(26) TABLE-US-00002 TABLE 2 Yield and by products. NTA-Na.sub.3 GLMA-Na.sub.3 Concentration of (HPLC) (HPLC) Yield by active ingredients GLDA-Na.sub.4 MGDA-Na.sub.3 (standardized to 40% (standardized to 40% Fe(III+) titration Fe(III+) titration (HPLC) (HPLC) by weight solution) by weight solution) # [%] [% by weight] [% by weight] [% by weight] [% by weight] [% by weight] Example 3 93.7 39.6 19.2 18.9 0.10 0.4 Example 4 97.0 34.4 16.3 16.2 0.05 0.7 Example 5 95.1 39.0 19.4 20.2 0.06 0.3 Example 6 91.5 40.3 18.3 21.4 0.22 0.3

EXAMPLE 7

(27) A mixture of 125.9 g MGDA-Na.sub.3 (40% by weight aqueous solution, ee=37%) and GLDA-Na.sub.4 (47% by weight aqueous solution, ee=95%) was prepared.

COMPARATIVE EXAMPLE 1

(28) A mixture of 125.9 g MGDA-Na.sub.3 (40% by weight aqueous solution, ee<5%) and GLDA-Na.sub.4 (47% by weight aqueous solution, ee<5%) was prepared.

COMPARISON OF EXAMPLES 7 to 9 and Comparative Example 1

(29) Table 3 summarizes the preparation of solutions of MGDA-Na.sub.3 and GLDA-Na.sub.4 and their concentration to approx. 60% by weight by evaporation of water in a rotatory evaporator. The solutions have been diluted by addition of water to 56% by weight and 40% by weight. The properties of the solutions are summarized in Table 4 and Table 5.

(30) TABLE-US-00003 TABLE 3 Parameters for the preparation and concentration of mixtures of Examples 7 to 9. Comparative Example 7 Example 8 Example 9 Example 1 MGDA-Na.sub.3 (ee 35%) [g] 125.9 GLDA-Na.sub.4 (ee 95%) [g] 105.9 MGDA-Na.sub.3 (ee <5%) [g] 134.6 GLDA-Na.sub.4 (ee <5%) [g] 97.0 Example 3 [g] 231.6 Example 4 [g] 235.7 Total mass [g] 231.9 231.6 235.7 231.6 Water evaporated [g] 64.1 82.0 96.4 74.5 Theoretical concentration [% by 59.6 61.3 58.2 58.3 of total actives weight] (MGDA/GLDA) Concentration of active [% by 60.4 61.4 57.2 59.5 ingredients weight] Fe(III+) titration

(31) TABLE-US-00004 TABLE 4 Properties of solutions diluted 56 to 57% by weight. Comparative Example 7 Example 8 Example 9 Example 1 Concentration of active [% by 56.7 56.9 56.1 56.3 ingredients weight] Fe(III+) titration [% by weight] Optical appearance clear solution clear solution clear solution clear solution Viscosity measured [mPas] 1650 1530 965 1630 with Brookfield, 23 C., spindle 31

(32) TABLE-US-00005 TABLE 5 Properties of solutions diluted to approx. 40% by weight. Comparative Example 7 Example 8 Example 9 Example 1 Concentration of active [% by 40.2 40.3 40.4 40.4 ingredients weight] Fe(III+) titration [% by weight] Specific rotation [deg ml 3.3 3.9 4.0 0.6 g.sup.1 dm.sup.1]

(33) The specific rotation measured by polarimetry is higher for Example 7 to 9 according to the present invention compared to the Comparative Example 1.