A method for stabilizing phosphite in an organic solution

Abstract

The application discloses a method for stabilizing phosphite in organic solution, which comprises adding organic phosphine compound into the organic solution containing phosphite, wherein the organic phosphine compound contains diorganophosphine compound. According to the method for stabilizing phosphite in organic solution, the stability of phosphite compound in the oxygen-containing environment is obviously improved, the loss of phosphite compound is reduced, and the requirement for the oxygen content of the use and storage environment is lowered.

Description

Technical Field

[0001] This invention relates to a method for stabilizing phosphites in organic solutions, which can be used to improve the stability of phosphites in oxygen-containing organic solution systems. Background Technology

[0002] The hydroformylation of olefins is an important organic synthesis process and a crucial route for the production of aldehydes, alcohols, and their derivatives. The rhodium phosphine catalytic system is currently the most widely used catalyst system. Among them, phosphite compounds, as fourth-generation catalyst ligands, exhibit high reaction activity, strong selectivity, and a high positive-to-negative ratio of products, and have been widely applied.

[0003] Compared to phosphine compounds, phosphite ligands are expensive and more prone to degradation. Minimizing ligand loss during use and storage is a major concern. In organic solvents, phosphite compounds are highly sensitive to oxygen, requiring extremely high oxygen content in all operating environments. According to literature, in the production of 2-propylheptanol, strict control of the oxygen content introduced into the system is necessary. During catalyst preparation, nitrogen purging must be performed promptly after the ligand is added to the preparation tank, and pentanal dissolution can only proceed when the oxygen content is ≤0.1%(v). Both the syngas purification system and the raffinate C4 purification system have deoxygenation beds. Typical control requirements are: oxygen content ≤0.1ppm(v) after syngas purification and ≤1ppm(wt) after raffinate C4 purification. The oxygen content in the buffer solution system also needs strict control and close monitoring during production to ensure that the oxygen content in the injected demineralized water and buffer solution is ≤0.2ppm(wt).

[0004] CN100355500C discloses a method for preserving group VIII B metal-organophosphite complex catalyst solutions. It points out that when preserving metal-organophosphite complex catalyst solutions containing free phosphite ligands using existing technologies, trace amounts of oxygen in the container not only oxidize the phosphite ligands but also further promote their decomposition, thereby causing deterioration. The solution should be stored in an atmosphere with an oxygen partial pressure of less than or equal to 10 Pa.

[0005] CN103702758B discloses a method for storing transition metal organophosphorus ligand-based catalysts, which specifies that phosphite-containing catalyst solutions should be stored under a syngas and inert gas covering layer.

[0006] However, the storage methods disclosed in the aforementioned patent applications all require strict control of the oxygen content in the system, and the use and operation conditions are quite stringent. Therefore, it is particularly important to improve the stability of phosphites in oxygen-containing organic solutions and environments. Summary of the Invention

[0007] The purpose of this invention is to improve the stability of phosphite compounds in oxygen-containing environments, reduce the loss of phosphite compounds, and provide a method for stabilizing phosphite in organic solutions.

[0008] To achieve the above objectives, the present invention provides a method for stabilizing phosphites in an organic solution, the method comprising: including an organophosphorus compound in the organic solution containing the phosphites, wherein the organophosphorus compound contains a bisorganophosphorus compound represented by formula (1).

[0009] Ar2P-L1-R-L2-PAr2 Equation (1)

[0010] Wherein, R is a substituted or unsubstituted C1-C12 alkylene group, a substituted or unsubstituted C6-C24 arylene group, or a substituted or unsubstituted carbon-containing heterocyclic divalent group; L1 and L2 are each a linking bond or a C1-C5 alkylene group; and Ar is a substituted or unsubstituted C6-C12 aryl group.

[0011] According to the method for stabilizing phosphites in organic solutions described in this invention, introducing a certain amount of organophosphorus compounds into an organic solution system containing phosphites can significantly improve the stability of phosphites in oxygen-containing environments, reduce the loss of phosphites, and lower the requirements for the oxygen content of the use and storage environment. Detailed Implementation

[0012] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0013] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0014] The method for stabilizing phosphites in an organic solution according to the present invention comprises: including an organophosphorus compound in an organic solution containing phosphites, wherein the organophosphorus compound contains a bis-organophosphorus compound represented by formula (1).

[0015] Ar2P-L1-R-L2-PAr2 formula (1)

[0016] Wherein, R is a substituted or unsubstituted C1-C12 alkylene group, a substituted or unsubstituted C6-C24 arylene group, or a substituted or unsubstituted carbon-containing heterocyclic divalent group; L1 and L2 are each a linking bond or a C1-C5 alkylene group; and Ar is a substituted or unsubstituted C6-C12 aryl group.

[0017] In formula (1), R can be a substituted or unsubstituted C1-C12 alkylene group, preferably a substituted or unsubstituted C3-C10 alkylene group, and more preferably a substituted or unsubstituted C4-C7 alkylene group. The substituent can be a halogen, a C1-C3 alkyl group, or a C1-C3 alkoxy group.

[0018] In formula (1), R can be a substituted or unsubstituted C6-C24 arylene group, preferably a group containing one benzene ring, two benzene rings, one naphthalene ring, or two naphthalene rings. The substituent can be a halogen, a C1-C3 alkyl group, or a C1-C3 alkoxy group.

[0019] In formula (1), R can be a substituted or unsubstituted divalent group containing a carbon heterocycle, preferably a divalent group containing a carbon heterocycle and a benzene ring, wherein the heteroatom in the carbon heterocycle is preferably oxygen. The substituent can be a halogen, a C1-C3 alkyl group, or a C1-C3 alkoxy group.

[0020] In a preferred embodiment, R is...

[0021]

[0022] In formula (1), L1 and L2 can each be a linking bond or a C1-C5 alkylene group, preferably a linking bond, methylene, ethylene or propylene.

[0023] In formula (1), Ar can be a substituted or unsubstituted C6-C12 aryl group, preferably a substituted or unsubstituted phenyl or naphthalene group, more preferably a substituted or unsubstituted phenyl group. The substituent can be a halogen or a C1-C3 alkyl group.

[0024] In a preferred embodiment of the present invention, the bisorganophosphine compound is at least one of the four compounds shown in the following formula.

[0025]

[0026] Ph refers to phenyl.

[0027] In the method for stabilizing phosphites in an organic solution according to the present invention, the organophosphorus compound further contains a single organophosphorus compound as shown in formula (2), that is, the organic solution containing phosphites contains a single organophosphorus compound in addition to a dual organophosphorus compound.

[0028]

[0029] In formula (2), R1, R2, and R3 may be the same or different, and each may be a substituted or unsubstituted C1-C24 hydrocarbon group. Preferably, R1, R2, and R3 are each a substituted or unsubstituted C1-C12 hydrocarbon group, more preferably a substituted or unsubstituted C3-C12 hydrocarbon group, even more preferably a substituted or unsubstituted C3-C12 cycloalkyl or a substituted or unsubstituted C6-C12 aryl group, and most preferably a substituted or unsubstituted phenyl or a substituted or unsubstituted cyclohexyl group. Here, optional substituents may be, for example, C1-C5 alkyl, C1-C5 alkoxy, or halogens (such as chlorine, bromine, or iodine).

[0030] In a specific embodiment, the organophosphorus compound is preferably at least one of triphenylphosphine, diphenylcyclohexylphosphine, and phenyldicyclohexylphosphine.

[0031] In the method described in this invention, the amount of organophosphorus compound introduced into the phosphite-containing organic solution can be appropriately adjusted according to differences in the oxygen dissolution properties, etc., of the different organic solvents used. Preferably, the content of the organophosphorus compound in the phosphite-containing organic solution is 0.01-1 wt%, more preferably 0.1-1 wt%, and even more preferably 0.2-0.6 wt%.

[0032] In the method described in this invention, in the organic solution containing phosphite, the content of the single organophosphine compound can be 0-100 parts by weight relative to 100 parts by weight of the dual organophosphine compound, preferably 0-50 parts by weight, more preferably 0-20 parts by weight, and even more preferably 0-10 parts by weight.

[0033] In the method described in this invention, in order to better stabilize the phosphite compound in the organic solution containing the phosphite, it is preferable that the organophosphine compound be added to the organic solvent earlier than the phosphite compound during solution preparation, storage, or use. In a preferred embodiment, the organophosphine compound is first dissolved in the organic solvent, and then the phosphite is added.

[0034] In this invention, the phosphite can be a conventional choice in the art. In a preferred embodiment, the phosphite is at least one of a single organic phosphite of formula (3) and a diorganic phosphite of formula (4) or (5).

[0035]

[0036] Wherein, R4, R4', R5 and R5' are each hydrogen, substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C6-C12 aryl or substituted or unsubstituted C1-C12 alkoxy, and R6 is substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alkylaryl or substituted or unsubstituted aralkyl.

[0037]

[0038] Wherein, R7, R7', R8 and R8' are each hydrogen, substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C6-C12 aryl or substituted or unsubstituted C1-C12 alkoxy, R9 and R9' are each substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alkylaryl or substituted or unsubstituted aralkyl, R10 and R10' are each substituted or unsubstituted alkylene, substituted or unsubstituted arylene, substituted or unsubstituted dialkylaryl or substituted or unsubstituted dialkylaryl, and X is substituted or unsubstituted alkylene or substituted or unsubstituted arylene.

[0039] More preferably, in the single organic phosphite shown in formula (3), R4, R4', R5 and R5' are each hydrogen or tert-butyl, and R6 is phenyl or 4-sulfonylphenyl.

[0040] More preferably, in the diorganophosphite shown in formula (4) or formula (5), R7, R7', R8 and R8' are each hydrogen or tert-butyl, R9 and R9' are each phenyl or 4-sulfonylphenyl, R10 and R10' are each phenylene or divalent 4-sulfonylphenyl, and X is divalent di(2,4-di-tert-butyl)biphenol.

[0041] As a specific embodiment of the present invention, the phosphite contained in the organic solution containing the phosphite is a compound represented by formula (6).

[0042] Where t-Bu refers to tert-butyl.

[0043] In the method described in this invention, the organic solvent contained in the phosphite-containing organic solution can be selected from any organic solvent capable of dissolving the phosphite compound. Specifically, the organic solvent can be at least one of the following: linear or branched C1-C30 alkanes, aromatics, aldehydes, alcohols, ketones, ethers, esters, sulfoxides, or phenols, with or without atoms other than carbon and hydrogen atoms; preferably, aldehydes and / or ethers. In the most preferred embodiment, the organic solvent is pentanal and / or tetraethylene glycol dimethyl ether.

[0044] In the method described in this invention, the phosphite-containing organic solution may or may not contain a catalyst capable of complexing with the phosphite compound. The catalyst is preferably a metal catalyst containing a Group VIII B metal, wherein the Group VIII B metal is preferably rhodium. In one specific embodiment, the metal catalyst is rhodium acetylacetone dicarbonyl.

[0045] The present invention will be described in detail below through embodiments.

[0046] In the following examples, the organic solvents used to prepare organic solutions containing phosphites were commercially available organic reagents. The purity of the pentaldehyde used was 97%, and the purity of the tetraethylene glycol dimethyl ether was 99%. The solvents used had been exposed to air for a period of time before use, and no distillation, deoxygenation, dehydration, or impurity removal was performed during use. All related operations such as solution preparation were also carried out in air. The prepared solutions were stored in sample bottles, and the gas atmosphere above the solutions was air.

[0047] The changes in phosphites and their oxidation products, monophosphate and diphosphate, in organic solutions were monitored by liquid chromatography analysis. In the following examples, apart from the oxidation products monophosphate and diphosphate, no other compounds produced by the deterioration of phosphites were detected in the liquid chromatography analysis. The proportions of phosphites and their oxidation products monophosphate and diphosphate in the determination results were the proportions of the concentrations of the three components to the total concentration of the three components after peak area normalization.

[0048] The phosphite used in the following examples has the structure shown in formula (6) and has a purity of approximately 98.5% when used.

[0049]

[0050] Reference Example 1

[0051] Weigh 0.25g of solid phosphite, dissolve it in pentaldehyde to a final concentration of 50g, and prepare a 0.5% phosphite-pentaldehyde solution. Monitor the composition of phosphite and its oxidation products, monophosphoric acid and diphosphoric acid, in the solution at regular intervals. The results are listed in Table 1.

[0052] Table 1

[0053] Placement time Phosphite / wt% monophosphate / wt% bisphosphonic acid / wt% 10min 23.1 52.4 24.5 40min 6.0 39.1 54.9 6h 1.5 22.4 76.1 24h 0.3 9.3 90.4 48h 0 1.2 98.8

[0054] As can be seen from the data in Table 1, phosphites are oxidized very rapidly in pentanal solution. More than 75% are oxidized in just 10 minutes, more than 98% are oxidized in 6 hours, and they are basically completely oxidized in 24 hours.

[0055] Example 1

[0056] Weigh 0.25g of the organophosphorus compound BISBI (structural formula shown in formula (1-1)), dissolve it in pentaldehyde to a final volume of 50g, and then add 0.25g of solid phosphite to prepare a pentaldehyde solution of BISBI and phosphite with a mass concentration of approximately 0.5%. At regular intervals, monitor the composition of phosphite and its oxidation products monophosphoric acid and diphosphoric acid in the solution. The results are listed in Table 2.

[0057] Table 2

[0058] Placement time Phosphite / wt% monophosphate / wt% bisphosphonic acid / wt% 10min 98.7 1.3 0 50min 98.7 1.3 0 24h 98.5 1.4 0.1 48h 97.8 1.8 0.4 7d 95.0 2.9 2.1

[0059] As can be seen from the data in Table 2, the addition of the organophosphorus compound BISBI to pentanal solution can effectively improve the stability of phosphite in oxypentanal solution.

[0060] Example 2

[0061] Weigh 0.25g of the organophosphorus compound BINAP (structural formula shown in formula (1-2)), dissolve it in pentaldehyde to a final volume of 50g, and then add 0.25g of solid phosphite to prepare a pentaldehyde solution of BINAP and phosphite with a mass concentration of approximately 0.5%. At regular intervals, monitor the composition of phosphite and its oxidation products monophosphate and diphosphate in the solution. The results are listed in Table 3.

[0062] Table 3

[0063] Placement time Phosphite / wt% monophosphate / wt% bisphosphonic acid / wt% 10min 98.6 1.4 0 50min 98.6 1.4 0 24h 98.5 1.5 0 48h 97.6 1.9 0.5 7d 95.4 3.0 1.6

[0064] As can be seen from the data in Table 3, the addition of the organophosphorus compound BINAP to pentanal solution can effectively improve the stability of phosphite in oxypentanal solution.

[0065] Example 3

[0066] Weigh 0.125 g of the organophosphorus compound BISBI (structural formula shown in formula (1-1)), dissolve it in pentaldehyde to a final volume of 50 g, and then add 0.25 g of solid phosphite to prepare a solution of BISBI with a mass concentration of approximately 0.25% and phosphite with pentaldehyde. At regular intervals, monitor the composition of phosphite and its oxidation products, monophosphoric acid and diphosphoric acid, in the solution. The results are listed in Table 4.

[0067] Table 4

[0068] Placement time Phosphite / wt% monophosphate / wt% bisphosphonic acid / wt% 10min 98.3 1.7 0 50min 95.5 3.9 0.6 24h 88.6 7.5 3.9 48h 84.9 10.1 5.0 7d 77.3 14.6 8.1

[0069] As can be seen from the data in Table 4, the stabilizing effect of the organophosphorus compound BISBI on phosphite decreases when the amount added to the pentanal solution is reduced.

[0070] Example 4

[0071] Weigh 0.25g of the organophosphorus compound BISBI (structural formula shown in formula (1-1)), dissolve it in pentaldehyde to a final volume of 50g, and then add 1.0g of solid phosphite to prepare a pentaldehyde solution with a mass concentration of approximately 0.5% BISBI and 1% phosphite. At regular intervals, monitor the composition of phosphite and its oxidation products monophosphoric acid and diphosphoric acid in the solution. The results are listed in Table 5.

[0072] Table 5

[0073] Placement time Phosphite / wt% monophosphate / wt% bisphosphonic acid / wt% 10min 98.6 1.4 0 50min 98.6 1.4 0 24h 98.3 1.7 0 48h 97.9 1.8 0.3 7d 95.6 2.9 1.5

[0074] As can be seen from the data in Table 5, the addition of the organophosphorus compound BISBI at a concentration of 0.5% can effectively stabilize phosphites in pentanal solution.

[0075] See Example 2

[0076] Weigh 0.125g of phosphite, dissolve it in tetraethylene glycol dimethyl ether to a final volume of 50g, and prepare a tetraethylene glycol dimethyl ether solution with a mass concentration of approximately 0.25% phosphite. At regular intervals, monitor the composition of phosphite and its oxidation products, monophosphoric acid and diphosphoric acid, in the solution. The results are listed in Table 6.

[0077] Table 6

[0078] Placement time Phosphite / wt% monophosphate / wt% bisphosphonic acid / wt% 30min 74.5 22.4 3.1 5h 28.2 37.7 34.1 24h 15.2 35.9 51.9 48h 9.8 25.3 64.9

[0079] As can be seen from the data in Table 6, phosphites are more stable in tetraethylene glycol dimethyl ether solution than in pentanal solution.

[0080] Example 5

[0081] Weigh 0.125g of the organophosphorus compound BISBI, dissolve it in tetraethylene glycol dimethyl ether to a final volume of 50g, then add 0.125g of solid phosphite to prepare a tetraethylene glycol dimethyl ether solution with a mass concentration of approximately 0.25% for both BISBI and phosphite. At regular intervals, monitor the composition of phosphite and its oxidation products, monophosphoric acid and diphosphoric acid, in the solution. The results are listed in Table 7.

[0082] Table 7

[0083] Placement time Phosphite / wt% monophosphate / wt% bisphosphonic acid / wt% 30min 98.5 1.5 0 6h 98.5 1.5 0 24h 98.3 1.3 0 7d 95.5 3.0 1.5

[0084] As can be seen from the data in Table 7, the addition of the organophosphorus compound BISBI to the tetraethylene glycol dimethyl ether solution can effectively improve the stability of phosphites in the oxygen-containing tetraethylene glycol dimethyl ether solution.

[0085] See Example 3

[0086] 0.037 g of rhodium dicarbonyl acetylacetone and 0.38 g of phosphite were weighed and prepared into a pentaldehyde solution containing rhodium-phosphite catalyst. The composition of phosphite and its oxidation products, monophosphoric acid and diphosphoric acid, in the solution was monitored. The results were the ratio of free phosphite to its oxidation products. Ligands bound to the catalyst were not included in the calculation. The results are listed in Table 8.

[0087] Table 8

[0088] Placement time Phosphite / wt% monophosphate / wt% bisphosphonic acid / wt% 7d 0.5 57.9 41.6

[0089] Example 6

[0090] Weigh 0.25 g of the organophosphorus compound BISBI, dissolve it in pentaldehyde to a final volume of 50 g, then add 0.037 g of rhodium dicarbonyl acetylacetone and 0.38 g of phosphite to prepare a pentaldehyde solution containing a rhodium-phosphite catalyst. Monitor the composition of phosphite and its oxidation products, monophosphoric acid and diphosphoric acid, in the solution. The results are the ratio of free phosphite to its oxidation products. Ligands bound to the catalyst are not included in the calculation. The results are listed in Table 9.

[0091] Table 9

[0092] Placement time Phosphite / wt% monophosphate / wt% bisphosphonic acid / wt% 7d 96.0 2.3 1.7

[0093] Comparison of Reference Example 3 and Example 6 shows that the addition of the organophosphorus compound BISBI can improve the stability of phosphites in the catalyst solution in an oxygen-containing environment.

[0094] The results above show that, according to the method for stabilizing phosphites in organic solutions described in this invention, introducing a certain amount of organophosphorus compounds into an organic solution system containing phosphites can significantly improve the stability of phosphites in an oxygen-containing environment and reduce the loss of phosphites.

[0095] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for stabilizing phosphites in an organic solution, characterized in that, The method includes: containing an organophosphorus compound in an organic solution containing a phosphite, wherein the organophosphorus compound contains a bis-organophosphorus compound, the bis-organophosphorus compound being at least one of four compounds represented by the following formula. Equation (1-1) Equation (1-2) Equation (1-3) Equation (1-4).

2. The method according to claim 1, characterized in that, The organophosphorus compound also contains a single organophosphorus compound as shown in formula (2). Equation (2) Among them, R1, R2 and R3 may be the same or different, and each is a substituted or unsubstituted C1-C24 hydrocarbon group.

3. The method according to claim 2, characterized in that, The single organophosphine compound is at least one of triphenylphosphine, diphenylcyclohexylphosphine, and phenyldicyclohexylphosphine.

4. The method according to any one of claims 1-3, characterized in that, In the organic solution containing phosphite, the content of the organophosphorus compound is 0.01-1 by weight.

5. The method according to claim 4, characterized in that, In the organic solution containing phosphite, the content of the organophosphorus compound is 0.1-1 by weight.

6. The method according to claim 5, characterized in that, In the organic solution containing phosphite, the content of the organophosphorus compound is 0.2-0.6% by weight.

7. The method according to any one of claims 1-3 and 5-6, characterized in that, The organophosphorus compound is first dissolved in an organic solvent, and then a phosphite is added.

8. The method according to claim 7, characterized in that, The phosphite is at least one of the single organic phosphite shown in formula (3) and the two organic phosphites shown in formula (4) or formula (5). Equation (3) Wherein, R4, R4', R5 and R5' are each hydrogen, substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C6-C12 aryl or substituted or unsubstituted C1-C12 alkoxy, and R6 is substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alkylaryl or substituted or unsubstituted aralkyl. Equation (4) Equation (5) Wherein, R7, R7', R8 and R8' are each hydrogen, substituted or unsubstituted C1-C12 alkyl, substituted or unsubstituted C6-C12 aryl or substituted or unsubstituted C1-C12 alkoxy, R9 and R9' are each substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alkylaryl or substituted or unsubstituted aralkyl, R10 and R10' are each substituted or unsubstituted alkylene, substituted or unsubstituted arylene, substituted or unsubstituted dialkylaryl or substituted or unsubstituted dialkylaryl, and X is substituted or unsubstituted alkylene or substituted or unsubstituted arylene.

9. The method according to claim 8, characterized in that, In the single organic phosphite shown in formula (3), R4, R4', R5 and R5' are each hydrogen or tert-butyl, and R6 is phenyl or 4-sulfonic acid phenyl.

10. The method according to claim 8, characterized in that, In the diorganophosphites shown in formula (4) or formula (5), R7, R7', R8 and R8' are each hydrogen or tert-butyl, R9 and R9' are each phenyl or 4-sulfonylphenyl, R10 and R10' are each phenylene or divalent 4-sulfonylphenyl, and X is divalent di(2,4-di-tert-butyl)biphenol.

11. The method according to claim 8, characterized in that, The phosphite contained in the organic solution is a compound represented by formula (6). Equation (6).

12. The method according to any one of claims 1-3, 5-6 and 8-11, characterized in that, The organic solvent contained in the phosphite-containing organic solution is at least one of the following: linear or branched C1-C30 alkanes, aromatics, aldehydes, alcohols, ketones, ethers, esters, sulfoxides, or phenols, with or without atoms other than carbon and hydrogen atoms.

13. The method according to claim 12, characterized in that, The organic solvent contained in the phosphite-containing organic solution is an aldehyde and / or an ether.

14. The method according to claim 12, characterized in that, The organic solution containing phosphite also contains a metal catalyst containing a Group VIII B metal.

15. The method according to claim 14, characterized in that, Group VIII B metal is rhodium.

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