Organic compounds -- part of the class 532-570 series – Organic compounds – Sulfonic acids or salts thereof
Reexamination Certificate
2001-06-25
2003-09-02
Vollano, Jean F (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Sulfonic acids or salts thereof
Reexamination Certificate
active
06613939
ABSTRACT:
CROSS-REFERENCE TO COMPANION APPLICATIONS
Copending application Ser. No. 09/886,288 and Ser. No. 09/886,289, both filed Jun. 22, 2001, both assigned to the assignee hereof, and both also hereby expressly incorporated by reference.
BACKGROUND OF THE INVENTION
1. Technical Field of the Invention
The-present invention relates to the preparation/purification of water-soluble sulfonated organophosphorus compounds which are particularly well suited as two-phase catalysts for a variety of organic reactions.
2. Description of the Prior Art
Organophosphorus compounds are particularly important as ligands for transition metal elements to prepare catalytic systems for various organic reactions such as carbonylation, hydroformylation, hydrocyanation and the isomerization of olefinic compounds.
Such catalytic systems are generally employed in reactions involving a single phase and, thus, an occasionally complex step of separation and recovery of the catalyst is required.
In the early 1970s, water-soluble compounds able to form complexes with metal elements in the oxidation state of zero were proposed as catalysts. These water-soluble compounds generally belong to the family of organophosphorus compounds comprising at least one sulfonate group. Thus, F. Joes and M. T. Beck, in an article published in
React. Kim. Catal. Letters,
2, 257 (1975), and Bawoski et al., in an article published in the review
Nouv. J. Chem.,
2, 137 (1978), describe a water-soluble monosulfonated triphenylphosphine which cannot be extracted using organic solvents.
The synthesis of these materials allowed the development of a novel method of catalysis referred to as two-phase catalysis. Specifically, the catalyst, i.e., transition metal elements complexed with water-soluble organophosphorus compounds, is present in an aqueous phase while the reagents are in an organic phase. Stirring and emulsification of the medium gives efficient catalysis. At the end of the reaction, the catalyst is recovered by simple separation by decantation of the two phases.
Rhône-Poulenc developed this technique for carrying out several important organic reactions such as the hydroformylation of olefins for the production of aldehydes, as described in FR-2,505,322 and FR-2,541,675. Another important application of this catalytic system, described, in particular, in FR-2,338,253 and FR-2,366,237, relates to the hydrocyanation reaction of olefins and the isomerization of the nitrites obtained, for example for the synthesis of adiponitrile, which is a major chemical intermediate for the manufacture of polyamide monomers.
Considerable research is nonetheless ongoing to improve the cost-effectiveness of these processes, in particular by increasing the cycle time and the lifetime of the catalytic system, as well as reducing the consumption of catalyst per quantity of adiponitrile produced.
Over the course of this research, degradation of the water-soluble sulfonated organophosphorus compounds has been observed.
SUMMARY OF THE INVENTION
Accordingly, a major object of the present invention is the provision of unique water-soluble sulfonated organophosphorus ligands which are resistant to degradation, and more stable two-phase catalytic systems comprised thereof.
Briefly, the present invention features carrying out organic reactions by two-phase catalysis, the media of reaction comprising an organic phase containing the reagents and the reaction products, an aqueous phase comprising a catalyst and a water-soluble sulfonated organophosphorus compound, wherein said water-soluble sulfonated organophosphorus compound has been purified via removal of contaminating sulfite compounds or radicals therefrom.
DETAILED DESCRIPTION OF BEST MODE AND SPECIFIC/PREFERRED EMBODIMENTS OF THE INVENTION
More particularly according to the present invention, in a preferred embodiment thereof, the sulfonated organophosphorus compounds thus purified have a weight concentration of sulfite of less than 100 ppm, preferably less than 50 ppm.
In another embodiment of this invention, the removal of sulfites is attained by converting same into sulfurous gas.
Exemplary organic reactions catalyzed via two-phase catalysis are hydroformylation, carbonylation, oxidation, isomerization and hydrocyanation reactions, in particular of unsaturated compounds.
In one preferred embodiment of the present invention, the hydrocyanation of organic compounds containing at least one ethylenic double bond is carried out to prepare nitrile compounds such as adiponitrile, for the synthesis of lactam, amino acid or amine monomers for the production of polyamides. This synthetic process, in particular, comprises a hydrocyanation of 3-pentenenitrile into adiponitrile, for which the catalyst comprising a sulfite-freed organophosphine in accordance with the invention as a component thereof is especially suitable.
Thus, in such an application, the lifetime of the catalyst can be greatly improved. This improvement is observed, in the case of the hydrocyanation of organic compounds comprising more than one ethylenic double bonds and in particular dienes, both for the hydrocyanation reaction of the first ethylenic bond and in that of the second ethylenic bond.
The process of the invention permits conducting the hydrocyanation of butadiene for the synthesis of adiponitrile with a catalyst based on water-soluble sulfonated organophosphorus ligands and on at least one metal element in oxidation state zero, with a consumption of catalyst per kg of adiponitrile produced which is markedly lower than that existing when using a catalyst or a ligand which has not been subjected to removal of sulfites.
In another preferred embodiment of the invention, removal of the sulfites contained in the water-soluble sulfonated organophosphorus compound is obtained by lowering the pH of the solution of organophosphorus compounds to a value of less than or equal to 4 and maintenance of such solution at a pH of less than or equal to 4 until a sulfite concentration in the solution of less than 100 ppm is attained.
Assay of the sulfite compounds in the solution is carried out, for example, by ionic chromatography.
The lowering of the pH of the solution can be accomplished by any suitable means. However, in another preferred embodiment of the invention, this lowering is accomplished by addition of a strong inorganic or organic acid in pure form or, more preferably, in solution.
The acidic solution can be a concentrated or dilute solution.
Exemplary acids which are suitable according to the present invention, representative are those acids having, for example, a pKa of less than or equal to 4, the corresponding anhydrides and more generally any compound which is chemically inert with respect to the organophosphorus compound and which can lower the pH of a solution.
Exemplary such acids are sulfuric acid, hydrochloric acid, trifluoroacetic acid, para-toluenesulfonic acid, perchloric acid and nitric acid.
Moreover, the solution of water-soluble sulfonated organophosphorus compounds is preferably an aqueous solution. However, solutions using water/alcohol mixtures as solvent are also suitable. The alcohol can be replaced with any water-miscible solvent.
In another embodiment of the invention, the solution is maintained at a pH of less than or equal to 4, at a temperature below 100° C. and advantageously ranging from 40° C. to 90° C.
The sulfurous gas produced by converting the sulfites is, in one preferred embodiment of the invention, removed from the reaction medium by entrainment with a carrier fluid. This carrier fluid is preferably nonoxidizing. Thus, carrier fluids which are suitable for the invention are, for example, nitrogen, carbon dioxide, water vapor, rare or inert gases, and oxygen-depleted air.
The water-soluble sulfonated organophosphorus compounds which are suitable for treatment according to the process of the invention and which are useful as ligands in the processes of two-phase catalysis are generally the sulfonated organophosphorus compounds prepared via one or more sulfonation steps as described in the article publish
Aouni Larbi
Burattin Paolo
Coqueret Pierre
Huser Marc
Burns Doane Swecker & Mathis L.L.P.
Rhodia Fiber & Resin Intermediates
Vollano Jean F
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