Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Patent
1995-07-11
1999-12-28
Barts, Samuel
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C07C 5114
Patent
active
060084081
DESCRIPTION:
BRIEF SUMMARY
This application was filed on Oct. 19, 1993 as International Application No. PCT/FR93/01028.
The present invention relates to a process for the hydroxycarbonylation of pentenoic acids for the preparation of adipic acid, in the presence of a catalyst which is at least partly separated from the reaction mixture obtained after the hydroxycarbonylation and reused in a hydroxycarbonylation operation.
One of the most promising processes for the preparation of adipic acid consists in hydroxycarbonylating one or a number of pentenoic acids, especially 3-pentenoic acid and 4-pentenoic acid, using carbon monoxide and water, in the presence of a catalyst based on iridium, rhodium or their mixtures and of an iodinated promoter. Generally, the reaction is carried out in the liquid phase at a temperature from 50.degree. C. to 300.degree. C. and under a partial carbon monoxide pressure of a few bar. In order to envisage the industrial use of a process of this type, it is very obviously indispensable to be able to recycle at least part of the expensive catalyst used.
The subject of the present invention is specifically a process containing such a recycling.
Among the separation techniques which can be envisaged, distillation of the more volatile compounds of the reaction mixture resulting from the hydroxycarbonylation allows the catalyst to remain with the diacids formed. A subsequent distillation of these diacids at low vapour pressure makes it necessary to subject them, and the catalyst, to a prolonged heating at a relatively high temperature, capable of degrading them and making the catalyst partially or entirely inactive.
The crystallization technique requires a sufficient heat transfer to be provided and for the production of crystals of a requisite size to be filtered off to be possible. In addition, the maximum level of solids is limited to an upper value of the order of 30 to 40%. All this leads to a significant equipment volume and to the immobilization of an excessively large amount of very expensive catalyst.
The present invention proposes to solve the problem of the separation and recycling of the catalyst in the context of a process for the hydroxycarbonylation of pentenoic acids to adipic acid, by the use of the refining technique.
More particularly, the subject of the invention is a process for the hydroxycarbonylation of pentenoic acids, characterized in that: by carbon monoxide and water, in the presence of a catalyst based on iridium and/or rhodium and of at least one iodinated promoter, having optionally been concentrated, making it possible to separate at least a part of the catalyst, hydroxycarbonylation of pentenoic acids or of butadiene or of butadiene derivatives.
Pentenoic acid is understood to mean, in the context of the invention, 2-pentenoic acid, 3-pentenoic acid, 4-pentenoic acid and their mixtures.
3-Pentenoic acid, taken in isolation or as a mixture with its isomers, is more particularly suitable, owing to its accessability and the satisfactory results to which it leads during its hydroxycarbonylation.
The catalyst used for the hydroxycarbonylation reaction can be based on rhodium, iridium or both these metals.
Any rhodium or iridium source is capable of being used.
Reference may be made, as examples of rhodium sources which can especially be used, to the compounds mentioned in European Patent EP-A-0,477,112, the contents of which are incorporated for reference in the present Patent Application.
Mention may be made, as examples of iridium sources which can especially be used, of:
The iridium-based catalyst which are more particularly suitable are: [IrCl(cod)].sub.2, Ir.sub.4 (CO).sub.12 and Ir(acac) (CO).sub.2.
The catalyst based on iridium or based on iridium and rhodium are particularly preferred in the context of the process of the invention.
The amount of catalyst to be used can vary within wide limits.
In general, an amount expressed in moles of metallic iridium and/or of metallic rhodium per liter of reaction mixture between 10.sup.-4 and 10.sup.-1 leads to satisfactory results. Lower
REFERENCES:
patent: 5166421 (1992-11-01), Bruner, Jr.
1st International Flock Conference, St. Petersburg State University of Technology and Design, Nov. 3-4, 1993.
Denis Philippe
Klinger Francois
Laurent Jean-Claude
Perron Robert
Schwartz Joel
Barts Samuel
Keys Rosalynd
Rhone-Poulenc Chimie
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