GB2247890A - Process for the removal of residual palladium from polyketones - Google Patents
Process for the removal of residual palladium from polyketones Download PDFInfo
- Publication number
- GB2247890A GB2247890A GB9115365A GB9115365A GB2247890A GB 2247890 A GB2247890 A GB 2247890A GB 9115365 A GB9115365 A GB 9115365A GB 9115365 A GB9115365 A GB 9115365A GB 2247890 A GB2247890 A GB 2247890A
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- GB
- United Kingdom
- Prior art keywords
- palladium
- polyketone
- polyketones
- organic solvent
- oxidising agent
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G67/00—Macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing oxygen or oxygen and carbon, not provided for in groups C08G2/00 - C08G65/00
- C08G67/02—Copolymers of carbon monoxide and aliphatic unsaturated compounds
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Polyethers (AREA)
Abstract
A process for the removal of residual palladium from polyketones comprises the step of treating the polyketone with an oxidising agent able to oxidise palladium from Pd(O) to a higher oxidation state under the conditions of the reaction and then by treatment with a co-ordinating organic solvent. Preferred solvent is acetonitrile and preferred oxidising agents are nitrosyl compounds eg nitrosyl tetrafluoroborate. Pd II or IV complexes such as [(CH3CN)4 Pd] (BF4)2 are prepared.
Description
PROCESS FOR THE REMOVAL OF RESIDUAL PALLADIUM
FROM POLYKETONES The present invention relates to a process for the removal of residual palladium from copolymers of alkenes and carbon monoxide.
Copolymers of alkenes and carbon monoxide, hereafter known as polyketones, are typically prepared by polymerising a mixture of one or more alkenes and carbon monoxide in the presence of an aryl phosphine complex of a palladium salt and an inert solvent (see for example US Patent 3694412). An alternative version of this process is disclosed in EP applications 181014 and 121965 wherein it is disclosed that the rate of polymerisation is greatly enhanced when the reaction is carried out in the presence of a palladium catalyst comprising a bidentate phosphine ligand and an anion of a carboxylic acid having a pKa of less than 2.Furthermore, our copending
British patent application no. 8909476.1 discloses a process for the preparation of polyketones comprising the step of copolymerising one or more alkenes with carbon monoxide in the presence of a palladium catalyst prepared by reacting a source of palladium, a bidentate phosphine ligand, a weakly co-ordinating anion of a borosalicylic acid and a quinone oxidant.
The polyketones produced by the above mentioned processes have excellent mechanical properties and may have potential use in a wide range of applications eg barrier materials, food and beverage packaging. A major problem is that a substantial amount of expensive palladium remains in the polyketone which cannot be removed by simple washing. The residual catalyst may also cause the polyketone to be coloured.
It would therefore be of great advantage to provide a process wherein the residual palladium is removed from the polyketone without causing degradation of the polymer during its removal.
Methods for removal of palladium metal from palladium compounds are known and can be carried out for example using the standard textbook method of washing the palladium containing compound with a mixture of concentrated nitric acid and chlorine gas. The metal is removed in the form of [H2PdC14]. If this process is applied to polyketones, the result is a dark brown product, suggesting that the polymer has decomposed.
An alternative method of removal of residual palladium from polyketones is disclosed in EP 0228733 wherein the polyketone is washed with an organic solvent such as methanol. EP 0224304 also discloses a similar process wherein the polyketone is washed with an organic solvent in the presence of carbon monoxide. Complexing agents are also introduced to the polyketone as disclosed in EP application 0283092 and examples are aryl phosphines, alkyl amines, salts of carboxylic acids eg acetate salts. In addition, a paper by
Schramm et al in Chem. Comm. 1968, pp. 898-99 describes a method of oxidising palladium(0) to palladium(II) in the preparation of square planar cationic Pd(II) complexes.
We have now unexpectedly shown that the latter process can be applied to remove residual palladium species from polyketones.
Accordingly, the present invention relates to a process for the removal of residual palladium from polyketones comprising the step of treating the polyketone with an oxidising agent able to oxidise palladium from Pd(0) to a higher oxidation state under the conditions of the reaction.
It is believed that the present invention solves the problem by the introduction of an oxidising agent able to oxidise palladium to a higher oxidation state. The oxidised palladium is then optionally removed from the polyketone by washing with a coordinating organic solvent able to complex the oxidised palladium.
It is preferred that the oxidising agent is one which can oxidise Pd(0) to either Pd(II) or Pd(IV). Particularly suitable oxidising agents are nitrosyl compounds and a most preferred example is nitrosyl tetrafluoroborate. The reaction is preferably carried out by reacting the palladium and the oxidising agent in the molar ratio ranging from 1:1 to 1:1000.
The reaction must be carried out in the substantial absence of oxygen when nitrosyl complexes are used to prevent the formation of nitrate ions. The reaction should therefore be carried out under an inert atmosphere, such as nitrogen or argon.
Regarding the coordinating organic solvent, suitably nitriles can be used. Acetonitrile is the preferred solvent.
The process can be carried out at atmospheric pressure. The temperature of the reaction is suitably ambient or up to the degradation temperature of the polymer. A particularly convenient temperature to use is the reflux temperature of the coordinating organic solvent.
The product obtained is a copolymer having reduced palladium content. In addition, the palladium removed from the copolymer is in general in the form of a complex. Where the combination of nitrosyl tetrafluoroborate and acetonitrile are used, the complex produced is thought to be [(CH3CN)4Pd](BF4)2.
The process of the present invention has the advantage that the recovered palladium, by virtue of being a soluble complex, can easily be converted back into the original catalyst for the polyketone forming reaction. Removal of the palladium from the polyketones can therefore provide a means of regeneration of the catalyst. Thus, this process step can be incorporated into the overall polyketone synthesis scheme and carried out continously.
The present invention will now be illustrated by reference to the following examples.
Example 1
A round bottomed flask fitted with a condenser and nitrogen inlet was charged with polyketone (2g) and acetonitrile (40cm3).
The vessel was sealed, evacuated and nitrogen gas introduced. The cycle of evacuation and introduction of nitrogen gas was repeated three times. Nitrosyl tetrafluoroborate (30mg) was added to the vessel under nitrogen and the resulting suspension magnetically stirred at room temperature for one hour. The vessel was opened and the polyketone isolated by filtration, followed by washings with boiling methanol (100cm3) and boiling acetone (100cm3). The polyketone was left to dry in air and analysed for palladium content using atomic absorption spectroscopy. The starting polyketone contained 46 ppm Pd and the washed polymer was found to contain 25 ppm Pd.
Example 2
The procedure of Example 1 was repeated except that 5.075g of polyketone was used in the reaction and the reaction was carried out over four hours. The residual palladium content of the washed polymer was 8 ppm.
Example 3
The procedure of Example 1 was repeated except 5g of the polyketone was used and the reaction was carried out under reflux.
The palladium content of the washed polymer was found to be lower than the detection limit of the atomic absorption spectrometer ( 5 ppm).
Claims (9)
1. A process for the removal of residual palladium from polyketones comprising the step of reacting a polyketone with an oxidising agent able to oxidise palladium from Pd(O) to a higher oxidation state under the conditions of the reaction.
2. A process as claimed in claim 1 wherein the palladium is oxidised to either Pd(II) or Pd(IV).
3. A process as claimed in claim 1 comprising additionally a second step in which the product obtained by reacting the polyketone with the oxidising agent is contacted with a coordinating organic solvent which removes the oxidised palladium from the polyketone.
4. A process as claimed in claim 3 wherein the polyketone is contacted with the oxidising agent and the coordinating organic solvent simultaneously.
5. A process as claimed in claim 1 wherein the oxidising agent is a nitrosyl complex.
6. A process as claimed in claim 5 wherein the oxidising agent is nitrosyl tetrafluoroborate.
7. A process as claimed in claims 5 or 6 carried out in the substantial absence of oxygen.
8. A process as claimed in claim 1 wherein the coordinating organic solvent comprises a compound containing a nitrile group.
9. A process as claimed in claim 8 wherein the coordinating organic solvent is acetonitrile.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB909020215A GB9020215D0 (en) | 1990-09-15 | 1990-09-15 | Process for the removal of residual palladium from polyketones |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9115365D0 GB9115365D0 (en) | 1991-08-28 |
| GB2247890A true GB2247890A (en) | 1992-03-18 |
Family
ID=10682283
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB909020215A Pending GB9020215D0 (en) | 1990-09-15 | 1990-09-15 | Process for the removal of residual palladium from polyketones |
| GB9115365A Withdrawn GB2247890A (en) | 1990-09-15 | 1991-07-16 | Process for the removal of residual palladium from polyketones |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB909020215A Pending GB9020215D0 (en) | 1990-09-15 | 1990-09-15 | Process for the removal of residual palladium from polyketones |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB9020215D0 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT504663B1 (en) * | 2007-02-22 | 2008-07-15 | Sanochemia Pharmazeutika Ag | PROCESS FOR THE PRODUCTION OF HIGH PURSES 4A, 5,9,10,11,12, -HEXAHYDRO-6H-BENZOFURO (3A, 3,2-F) (2) BENZAZEPINES AND THEIR DERIVATIVES |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0283092A1 (en) * | 1987-03-13 | 1988-09-21 | Shell Internationale Researchmaatschappij B.V. | Process for removing palladium catalyst remnants from copolymers of carbon monoxide with one or more olefinically unsaturated compounds |
| EP0285218A2 (en) * | 1987-03-27 | 1988-10-05 | Shell Internationale Researchmaatschappij B.V. | Removal of catalyst remnants from olefin/CO copolymers |
| US4870156A (en) * | 1988-09-27 | 1989-09-26 | Shell Oil Company | Removal of catalyst residues from olefin/carbon monoxide polymer with dithiocarbamate |
| EP0227135B1 (en) * | 1985-11-26 | 1991-07-24 | Shell Internationale Researchmaatschappij B.V. | Removal of catalyst remnants from ethene/co copolymers |
-
1990
- 1990-09-15 GB GB909020215A patent/GB9020215D0/en active Pending
-
1991
- 1991-07-16 GB GB9115365A patent/GB2247890A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0227135B1 (en) * | 1985-11-26 | 1991-07-24 | Shell Internationale Researchmaatschappij B.V. | Removal of catalyst remnants from ethene/co copolymers |
| EP0283092A1 (en) * | 1987-03-13 | 1988-09-21 | Shell Internationale Researchmaatschappij B.V. | Process for removing palladium catalyst remnants from copolymers of carbon monoxide with one or more olefinically unsaturated compounds |
| EP0285218A2 (en) * | 1987-03-27 | 1988-10-05 | Shell Internationale Researchmaatschappij B.V. | Removal of catalyst remnants from olefin/CO copolymers |
| US4870156A (en) * | 1988-09-27 | 1989-09-26 | Shell Oil Company | Removal of catalyst residues from olefin/carbon monoxide polymer with dithiocarbamate |
Non-Patent Citations (1)
| Title |
|---|
| Chem. Commun. 15 898-9 (1968) * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT504663B1 (en) * | 2007-02-22 | 2008-07-15 | Sanochemia Pharmazeutika Ag | PROCESS FOR THE PRODUCTION OF HIGH PURSES 4A, 5,9,10,11,12, -HEXAHYDRO-6H-BENZOFURO (3A, 3,2-F) (2) BENZAZEPINES AND THEIR DERIVATIVES |
| US8212029B2 (en) | 2007-02-22 | 2012-07-03 | Sanochemia Pharmazeutika Ag | Method for the production of high-purity 4a, 5, 9, 10, 11, 12,-hexahydro-6H-benzofuro [3a, 3, 2-ef] [2] benzazepine, and the derivatives thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9020215D0 (en) | 1990-10-24 |
| GB9115365D0 (en) | 1991-08-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |