Purification of Phosphorus Chelate Ligands

Abstract

A process for purifying phosphorus chelate ligands by extraction, by using polar extractants.

Description

EXAMPLES

All examples with ligands 1, 2 and 3 were carried out under an argon atmosphere (protective gas atmosphere):

Example 1

Extraction with Adiponitrile and Subsequent and Heating of Ligand 1

600 g of a 60% toluenic solution of ligand 1 (crude ligand), prepared according to DE-A-102 30 222, were admixed with 600 g of methylcyclohexane and extracted at room temperature 6 times with in each case 60 g of adiponitrile.

The upper phase was in each case admixed with 3-pentenenitrile and heated at 100° C. for 48 h. After the heating, the content of intact ligand 1 was determined by means of ³¹P NMR.

The results are compiled in Table 1.

TABLE 1
Extraction with adiponitrile
							Ligand 1
		Methylimidazole	Methylimidazole			Ligand 1	content
	Mass	hydrochloride	hydrochloride	Methylimidazole	Methylimidazole	content	after heating
	(g)	(ppm)	(mg)	(GC %)	(g)	[%]	[%]
Crude	600	820	492	1.72	10.32	95
ligand
1st upper	1212.2	82	99	0.373	4.52		51
phase
2nd upper	1191	45	53	0.077	0.92		79
phase
3rd upper	1181.3	30	35	—	—		91
phase
4th upper	1168.2	24	28	—	—		92
phase
5th upper	1157.3	20	23	—	—		93
phase
6th upper	1145.5	20	23	—	—		93
phase
1st lower	47.8	3900	186	8.924	4.27
phase
2nd lower	81.2	3000	243	4.606	3.74
phase
3rd lower	69.7	1100	77	2.001	1.39
phase
4th lower	73.1	440	32	0.807	0.60
phase
5th lower	70.9	120	9	0.310	0.22
phase
6th lower	71.8	32	2	0.063	0.05
phase
			549		10.3

Example 2

Extraction with Methylglutaronitrile and Subsequent Heating of Ligand 1

The procedure was analogous to Example 1 with methylglutaronitrile instead of adiponitrile.

The results are compiled in Table 2.

TABLE 2
Extraction with methylglutaronitrile
							Ligand 1
		Methylimidazole	Methylimidazole			Ligand 1	content
	Mass	hydrochloride	hydrochloride	Methylimidazole	Methylimidazole	content	after heating
	(g)	(ppm)	(mg)	(GC %)	(g)	[%]	[%]
Crude	600	820	492	1.94	11.6	94
ligand
1st upper	1219	22	27	0.40	4.9		76
phase
2nd upper	1200	19	23	0.14	1.7		85
phase
3rd upper	1185	19	23	0.03	0.4		91
phase
4th upper	1169	20	23	—	—		92
phase
5th upper	1157	17	20	—	—		92
phase
6th upper	1143	17	19	—	—		92
phase
1st lower	41	8000	328	8.90	3.6
phase
2nd lower	79	2200	174	4.51	3.6
phase
3rd lower	75	360	27	2.14	1.6
phase
4th lower	76	56	4	1.01	0.8
phase
5th lower	72	12	1	0.46	0.3
phase
6th lower	74	7	1	0.22	0.2
phase
			534		10.1

Example 3

Stability of Ligand 2 in 3-Pentenenitrile

0.15 g of ligand 2 was dissolved in 3 g of 3-pentenenitrile, admixed with the amounts of methylimidazole visible from Table 3 and heated to 100° C. under an argon atmosphere in a heating block for 17 h, and the residual content of ligand 2 was determined by ³¹P NMR spectroscopy:

TABLE 3
Methylimidazole Residual content of ligand 2
1000 ppm        0%
500 ppm         5%
250 ppm         18%
125 ppm         45%
65 ppm          68%
35 ppm          87%

The results from Table 3 show that ligand 2 is sufficiently stable from a methylimidazole content of <100 ppm.

Example 4

Stability of Ligand 3 in 3-Pentenenitrile

0.15 g of ligand 3 was treated with 3 g of 3-pentenenitrile analogously to Example 3. The result was determined by ³¹p NMR spectroscopy and was compiled in Table 4:

TABLE 4
                Residual chelate
Methylimidazole ligand content
1000 ppm        55%
65 ppm          98%

Claims

1. A process for purifying phosphorus chelate ligands comprising extracting and optionally phase separating phosphorus chelate ligands with polar extractants at temperatures of from (−20) to 150° C. and a pressure of from 1 to 5000 Pa.

2. The process for purifying phosphorus chelate ligands by extraction according to claim 1, wherein the phosphorus chelate ligands are bidentate phosphites, phosphinites, phosphite phosphinites, phosphite phosphonites and phosphonites.

3. The process for purifying phosphorus chelate ligands by extraction according to claim 1, wherein the temperature is at least 0° C.

4. The process for purifying phosphorus chelate ligands by extraction according to claim 1, wherein the temperature is at most 100° C.

5. The process for purifying phosphorus chelate ligands by extraction according to claim 1, wherein the pressure is at least 1 kPa.

6. The process for purifying phosphorus chelate ligands by extraction according to claim 1, wherein the pressure is at most 2000 Pa.

7. The process for purifying phosphorus chelate ligands by extraction according to claim 1, wherein the polar extractants are dinitriles.

8. The process for purifying phosphorus chelate ligands by extraction according to claim 1, wherein the polar extractant is adiponitrile or methylglutaronitrile.

9. The process for purifying phosphorus chelate ligands by extraction according to claim 1, wherein an aliphatic or cycloaliphatic hydrocarbon or a mixture thereof is added to the phosphorus chelate ligands before or during the extraction or the optional phase separation.

10. The process for purifying phosphorus chelate ligands by extraction according to claim 9, wherein the aliphatic or cycloaliphatic hydrocarbon added to the phosphorus chelate ligand before or during the extraction or phase separation is selected from the group consisting of n-heptane, n-octane, cyclohexane, methylcyclohexane and mixtures thereof.

11. The process for purifying phosphorus chelate ligands by extraction according to claim 1, wherein the purified phosphorus chelate ligands have a content of amine base, amine hydrochloride or mixtures thereof of less than 100 ppm.

12. The process for purifying phosphorus chelate ligands by extraction according to claim 2, wherein the temperature is at least 0° C.

13. The process for purifying phosphorus chelate ligands by extraction according to claim 2, wherein the temperature is at most 100° C.

14. The process for purifying phosphorus chelate ligands by extraction according to claim 3, wherein the temperature is at most 100° C.

15. The process for purifying phosphorus chelate ligands by extraction according to claim 2, wherein the pressure is at least 1 kPa.

16. The process for purifying phosphorus chelate ligands by extraction according to claim 3, wherein the pressure is at least 1 kPa.

17. The process for purifying phosphorus chelate ligands by extraction according to claim 4, wherein the pressure is at least 1 kPa.

18. The process for purifying phosphorus chelate ligands by extraction according to claim 2, wherein the pressure is at most 2000 Pa.

19. The process for purifying phosphorus chelate ligands by extraction according to claim 3, wherein the pressure is at most 2000 Pa.

20. The process for purifying phosphorus chelate ligands by extraction according to claim 4, wherein the pressure is at most 2000 Pa.