JP2003096187A - Method for producing polyketone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for efficiently and safely producing a polyketone at a high yield per weight of a catalyst without deterioration in catalyst activity in polymerization. SOLUTION: The method for producing a polyketone comprises copolymerizing carbon monoxide with an ethylenically unsaturated compound using as a catalyst a metal complex composed of at least one compound (a) of a transition metal selected among groups 9, 10 and 11 and a ligand (c), where the copolymerization is carried out in the presence of a metal compound (b) capable of oxidizing the transition metal.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyketone. More specifically, in the copolymerization of carbon monoxide and an ethylenically unsaturated compound with a metal complex catalyst,
The present invention relates to a method for producing a polyketone in the presence of a specific metal compound capable of oxidizing a transition metal element, safely and in good yield.

[0002]

BACKGROUND OF THE INVENTION A copolymer of carbon monoxide and an ethylenically unsaturated compound, particularly a polyketone having a structure in which carbon monoxide and an ethylenically unsaturated compound are substantially alternately linked, has mechanical and thermal properties. It has excellent abrasion resistance, chemical resistance, and gas barrier properties, making it a useful material for various applications. Various methods are known as methods for producing such polyketones. For example, in US Pat. No. 3,984,388, a nickel compound is used as a catalyst to react with carbon monoxide and α
-A method of copolymerizing with an olefin is described in US Pat.
The specification of 89460 discloses a method of using palladium as a catalyst and the like. However, these methods have a problem that the yield of polyketone per catalyst is low.

In order to improve this point, European Patent No. 31
No. 9083, U.S. Pat. No. 4,925,917, and the like, methanol is used as a solvent, and a palladium compound, 1,
A technique for dramatically improving the yield of polyketone by using a catalyst composed of 3-bis {di (2-methoxyphenyl) phosphino} propane and an anion of an acid is disclosed. However, according to these methods, the yield of polyketone per catalyst is improved, but when the polymerization is carried out for a long time, there is a problem that the catalytic activity decreases with the polymerization time.

As a method of improving the problem of the decrease in the catalytic activity, European Patent No. 257663 and European Patent No. 3
In the specification of 60359, when an organic oxidizing agent such as a quinone compound (1,4-benzoquinone, 1,4-naphthoquinone or anthraquinone) is allowed to coexist in the reaction system,
It is stated that the high catalytic activity continues. This is because the quinone compound, which is a strong oxidant, oxidizes the palladium that is gradually reduced and deactivated in the reaction system.
It is considered that the active state of the catalyst is maintained.

In this method, the quinone compound must be continuously added during the polymerization reaction in order to maintain high catalytic activity (European Patent Nos. 614928 and 734336). However, the quinone compound is an organic compound having a strong oxidizing action and is highly toxic, which is not preferable in terms of environmental safety. Furthermore, it is essential to wash and recover the quinone compound in the process of taking out the polymer, and after oxidizing palladium, it is extremely difficult to reuse the quinone that has been reduced and lost its oxidizing ability. The use of quinone compounds is also not economically preferable.

As a method for polymerizing a polyketone containing a metal compound as a catalyst component, JP-A-62-212433 and JP-A-6-322105 disclose methods for polymerizing in the presence of a metal cation. . The metal used in these prior arts only acts as a counter ion of an anion, which is one of the catalyst components, and the catalytic activity decreases with the polymerization time and the transition metal element in the catalyst component is reduced. No mention is made of oxidation.

[0007]

An object of the present invention is to provide a method for efficiently and safely producing polyketones, which has a high yield of polyketones per catalyst and does not decrease or deactivate the catalyst activity during polymerization. Is to provide.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the inventors of the present invention have conducted extensive studies on a method for producing a polyketone in which carbon monoxide and an ethylenically unsaturated compound are polymerized in the presence of a catalyst. As a result, it was found that the presence of a metal compound capable of oxidizing a transition metal element used as a catalyst in the reaction system allows the catalytic activity to be maintained and the yield of polyketone to be remarkably increased, and to complete the present invention. I arrived.

That is, according to the present invention, as a catalyst,
Copolymerizing carbon monoxide with an ethylenically unsaturated compound using a metal complex consisting of a compound (a) of at least one transition metal selected from Group 10, Group 10 and Group 11 and a ligand (c) In the method for producing a polyketone, the polyketone is copolymerized in the presence of the metal compound (b) capable of oxidizing the transition metal.

The present invention will be described in detail below. The catalyst in the polymerization of polyketone in the present invention means a compound of at least one transition metal selected from Group 9, Group 10 and Group 11 of the Periodic Table (Inorganic Chemistry Nomenclature (1993) Tokyo Kagaku Dojin ( It is a metal complex composed of a) and a ligand (c). Preferably, such a compound (a) of at least one transition metal selected from Group 9, 10, and 11 and a ligand (c) having an atom of Group 15
Is a catalyst composed of a metal complex in which an acid anion (d) is added.

The most important point of the present invention is that when the above catalyst is used, a metal compound (b) capable of oxidizing the transition metal constituting the transition metal compound (a) is present. In order to obtain the polyketone in good yield, there is a method of improving the polymerization reaction rate by the catalyst. However, a catalyst having a high activity is sensitive to a catalyst poison, and since a very small amount is required, deactivation of the catalyst at the time of production becomes a big problem. Therefore, maintaining the active state of the catalyst is important. It has been found that this problem can be achieved by the process according to the invention of the presence of a metal compound (b) capable of oxidizing the transition metal element used as catalyst.

A preferred metal compound (b) having an oxidizing ability with respect to the above transition metal contains at least one metal selected from copper, iron, manganese, tungsten, molybdenum, aluminum, lithium and vanadium. It is a compound. Among these, more preferable are compounds containing at least one metal selected from copper, iron, manganese, and vanadium, and specifically, cupric chloride, ferric chloride, manganese oxide. , Vanadium oxide sulfate, and the like, and among them, cupric chloride is most preferable.

Regarding the action and effect of the metal compound (b),
It is estimated as follows. The catalyst exists as a transition metal cation in an oxidized state in the reaction system and advances the polymerization reaction. However, it is reduced by some factor and becomes inactive. At this time, since the transition metal is oxidized by the metal compound (b), the active state of the catalyst is maintained. In order to obtain the above-described oxidation effect, the metal compound (b) and the compound of the transition metal may be brought into contact with each other in any production process, for example, a method of allowing them to coexist in a polyketone polymerization reaction system, a polymer at the time of polymer recovery The method of contacting with the compound of the transition metal recovered by the washing of (3) outside the reaction system can be mentioned.

After acting as an oxidant, the metal compound (b)
Is reduced and loses its oxidizing ability, but when it is directly oxidized by oxygen or an organic oxidizing agent such as alkyl nitrite or an inorganic oxidizing agent such as manganese oxide, hydrogen peroxide or heteropolyacid, the oxidizing ability is imparted again. , Can be reused. There is no limitation on the method of oxidizing the metal compound (b). Examples of the oxidation method include a method in which oxygen coexists in the polymerization reaction system, a method in which a part of the polymer is taken out when the polymer is recovered and brought into contact with oxygen or another oxidizing agent, and then returned to the reaction system.

When the amount of the metal compound (b) is too small with respect to the transition metal, the effect is small, and when it is too large, not only the cost but also the residual amount in the produced polymer is likely to occur.
Coloring is likely to occur. The metal compound (b) is preferably 1.0 to 100 mol, and more preferably 5.0 to 50 mol, per 1.0 mol of the transition metal compound (a).

The transition metal compound used in the present invention is
At least one transition element selected from the 9th, 10th, and 11th groups (Physical and Chemical Dictionary, 3rd edition, supplementary edition (1985))
Iwanami Shoten p. 740). Examples of the compound of the Group 9 transition metal include cobalt or ruthenium complexes, carboxylates, phosphates, carbamates, sulfonates, and the like. Specific examples thereof include cobalt acetate and cobalt. Examples thereof include acetyl acetate, ruthenium acetate, ruthenium trifluoroacetate, ruthenium acetyl acetate, ruthenium trifluoromethanesulfonate, and the like. Examples of compounds of the Group 10 transition metal include nickel or palladium complexes,
Examples thereof include carboxylates, phosphates, carbamates, sulfonates, and the like. Specific examples thereof include nickel acetate, nickel acetylacetonate, palladium acetate, palladium trifluoroacetate, palladium acetylacetonate, and chloride. Palladium, bis (N, N-diethylcarbamate) bis (diethylamino) palladium,
Palladium sulfate etc. can be mentioned. Examples of the Group 11 transition metal compound include copper or silver complexes, carboxylates, phosphates, carbamates, sulfonates, and the like, and specific examples thereof include copper acetate and triacetate. Examples thereof include copper fluoroacetate, copper acetylacetonate, silver acetate, silver trifluoroacetate, silver acetylacetonate, and silver trifluoromethanesulfonate.

Of these, the inexpensive and economically preferable transition metal compounds (a) are nickel and copper compounds, and the preferable transition metal compounds (a) in view of the yield and molecular weight of polyketone are palladium compounds. Is.

Ligand means the chemistry dictionary 7 miniature edition 16th edition (1974) Kyoritsu Shuppan. As defined in 4, it refers to an atomic group containing an atom directly bonded to a central atom in a complex. When the number of bonded atoms is one, it is a monodentate ligand. It is called a bidentate ligand.

As the ligand (c) in the present invention, a ligand having an atom of Group 15 is preferable, and examples thereof include a monodentate ligand of nitrogen such as pyridine; triphenylphosphine, trinaphthylphosphine and the like. A monodentate phosphorus ligand;
Arsenic monodentate ligands such as triphenylarsine; Antimony monodentate ligands such as triphenylantimony; 2,2'-
Nitrogen bidentate ligands such as bipyridyl, 4,4'-dimethyl-2,2'-bipyridyl, 2,2'-bi-4-picoline and 2,2'-biquinoline; 1,2-bis (diphenylphosphine) Fino) ethane, 1,3-bis (diphenylphosphino) propane, 1,4-bis (diphenylphosphino)
Butane, 1,3-bis {di (2-methyl) phosphino}
Propane, 1,3-bis {di (2-isopropyl) phosphino} propane, 1,3-bis {di (2-methoxyphenyl) phosphino} propane, 1,3-bis {di (2
-Sodium methoxy-4-sulfonate-phenyl) phosphino} propane, 1,2-bis (diphenylphosphino) cyclohexane, 1,2-bis (diphenylphosphino) benzene, 1,2-bis {(diphenylphosphino) Methyl} benzene, 1,2-bis [{di (2-methoxyphenyl) phosphino} methyl] benzene, 1,
2-bis [{sodium di (2-methoxy-4-sulfonate-phenyl) phosphino} methyl] benzene, 1,
1'-bis (diphenylphosphino) ferrocene, 2-
Hydroxy-1,3-bis {di (2-methoxyphenyl) phosphino} propane, 2,2-dimethyl-1,
Examples thereof include phosphorus bidentate ligands such as 3-bis {di (2-methoxyphenyl) phosphino} propane.

Of these, particularly preferred ligand (c)
Is a phosphorus bidentate ligand. Particularly preferred linnidentate ligand from the viewpoint of polyketone yield is 1,3-bis {di (2
-Methoxyphenyl) phosphino} propane and 1,2
-Bis [{di (2-methoxyphenyl) phosphino} methyl] benzene, and in terms of the molecular weight of polyketone, 2-hydroxy-1,3-bis {di (2-methoxyphenyl) phosphino} propane and 2, It is 2-dimethyl-1,3-bis {di (2-methoxyphenyl) phosphino} propane. From the viewpoint of being safe without requiring an organic solvent, water-soluble 1,3-bis {di (2-methoxy-4-sulfonic acid sodium-phenyl) phosphino} propane and 1,2-bis [{di ( 2-Methoxy-4-sulfonate sodium-phenyl) phosphino}
Methyl] benzene is preferred. 1,3, which is easy to synthesize, available in large quantities, and economically preferable
-Bis (diphenylphosphino) propane and 1,4-
Bis (diphenylphosphino) butane.

Examples of the acid anion (d) in the present invention include organic acid anions having a pKa of 4 or less such as trifluoroacetic acid, trifluoromethanesulfonic acid and p-toluenesulfonic acid; perchloric acid and sulfuric acid. , Nitric acid, phosphoric acid, heteropolyacid, tetrofluoroboric acid, hexafluorophosphoric acid, fluorosilicic acid, and the like, anions of inorganic acids having a pKa of 4 or less; Examples thereof include anions of boron compounds such as borate and N, N-dimethylanilium tetrakis (pentafluorophenyl) borate.

Of these, preferred acid anions (d)
Is an anion of an inorganic acid having a pKa of 4 or less. Sulfuric acid is most preferred for producing a high molecular weight polyketone in high yield. pKa is a numerical value defined by pKa = -log10Ka when the dissociation constant of acid is Ka, and the smaller the value, the stronger the acid. The amount of the transition metal compound (a) to be used cannot be unconditionally defined because its suitable value varies depending on the kind of the ethylenically unsaturated compound selected and other polymerization conditions, but it is preferably the reaction The volume of the zone is 0.001 to 100 mmol, and more preferably 0.01 to 10 mmol per liter. The volume of the reaction zone refers to the volume of the liquid phase of the reactor.
The amount of the ligand (c) used is also not limited, but it is preferably 0.1 to 10 mol, and more preferably 1 to 3 mol, per 1 mol of the compound (a) of the transition metal. The amount of the acid anion (d) used is preferably 0.1 to 10000 mol, and more preferably 1 to 1000 mol, per mol of the transition metal compound (a).

The catalyst of the present invention comprises components (a) and (c), preferably components (a), (c), and (d).
Produced by contacting the components. As a method of contacting, any method can be adopted. For example,
In the case of the catalyst comprising the components (a), (c) and (d), it may be used as a solution in which the three components are mixed in advance in a suitable solvent, or the three components may be separately supplied to the polymerization system for polymerization. You may make it contact in a system. Further, the complex obtained by previously reacting the component (a) with the component (c) may be brought into contact with the component (d).

Examples of the ethylenically unsaturated compound copolymerizable with carbon monoxide in the present invention include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-
Α-olefins such as decene; alkenyl aromatic compounds such as styrene and α-methylstyrene; cycloolefins such as cyclopentene, norbornene, 5-methylnorbornene, tetracyclododecene, tricyclodecene, pentacyclopentadecene, pentacyclohexadecene ; Vinyl halide such as vinyl chloride; ethyl acrylate;
Examples thereof include acrylic acid esters such as methyl methacrylate. Among these, preferred ethylenically unsaturated compounds are α-olefins, and more preferred ethylenically unsaturated compounds are α-olefins having 2 to 4 carbon atoms. The most preferred ethylenically unsaturated compound is ethylene. These ethylenically unsaturated compounds may be used alone or as a mixture of two or more kinds.

When the ethylenically unsaturated compound is used as a mixture of plural kinds, it is preferable to select ethylene as one of the components from the viewpoint of thermal stability as a material of the obtained polyketone, and more preferably, 90% or more of ethylene is contained in the total molar amount of the ethylenically unsaturated compound used. The carbon monoxide and the above ethylenically unsaturated compound in the method of the present invention are used in a gas or liquid state. Since the suitable value of the usage ratio varies depending on the type of ethylenically unsaturated compound used, the range cannot be unconditionally determined, but the molar ratio of (ethylenically unsaturated compound) / (carbon monoxide) is usually used. Is 0.1-1
It is 0, preferably 0.3 to 4.

In carrying out the method of the present invention, a known polymerization method / manufacturing process can be used. For example, the polymerization method may be a solution polymerization method using a liquid medium, a suspension polymerization method, or a small amount of polymer. A gas phase polymerization method in which a high-concentration catalyst solution is impregnated is used, and the process may be either batch type or continuous type. As the liquid medium used for polymerizing the polyketone, various solvents can be used, and there is no limitation as long as it can dissolve the ethylenically unsaturated compound and carbon monoxide. Examples of the liquid solvent used include water, alcohols such as methanol, ethanol, propanol, butanol, hexafluoroisopropanol, and ethylene glycol; phenols such as m-cresol; amines such as aniline; ketones such as acetone and methyl ethyl ketone. Examples thereof include ethers such as diethyl ether, tetrahydrofuran, diglyme, nitriles such as acetonitrile, esters such as acetic acid and methyl acetate, and these are used alone or as a mixed solvent of plural kinds. From the viewpoint of economical efficiency and handling safety, alcohols are preferable, and methanol is more preferable.

There is no limitation on the polymerization temperature, and it is generally 4
0 to 180 ° C., preferably 50 to 120 ° C. is adopted. There is no limit to the pressure, but generally atmospheric pressure to 20M
Pa, preferably 1 to 10 MPa.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to Examples. In the examples, methanol is completely dried methanol obtained by further dehydrating dehydrated one for organic synthesis with magnesium sulfate under a dry nitrogen stream before polymerization. Sulfuric acid was prepared by using a reagent grade 96% sulfuric acid, which had a water content of 4%, and was adjusted to have the sulfuric acid usage amount and water content described in Examples.
Polymerization was carried out. The measuring method of each measured value used in the present invention is as follows. (1) Intrinsic viscosity Intrinsic viscosity [η] is a value obtained based on the following defining equation. [Η] = lim [(T−t) / (t · C)] C → 0 t and T in the definition formula are hexafluoroisopropanol having a purity of 98% or more and a dilute solution of polyketone dissolved in hexafluoroisopropanol. C, is the solute weight value in grams in 100 ml of the above solution.

(2) Catalytic activity unit The amount of gram of palladium and the yield of polyketone per unit time are shown. Catalytic activity (kg / g-Pd · hr) = polyketone yield (kg) / [molar amount of Pd (mol) × atomic weight of Pd (g / mol) × polymerization time (hr)]

[0030]

Example 1 Palladium chloride (2.5 micromol) was placed in a stainless steel 100 ml autoclave in which nitrogen was replaced.
1,3-bis {di (2-methoxyphenyl) phosphino} propane 3 μmol, sulfuric acid 50 μmol,
And 50 micromoles of cupric chloride, 44m of methanol
50 ml of methanol-water mixed solvent consisting of 1 and 6 ml of water
It was added to the solution dissolved in. After sealing the autoclave,
The contents were heated with stirring, and when the internal temperature reached 85 ° C., an equimolar mixed gas of carbon monoxide and ethylene was added until the internal pressure of the autoclave reached 5.5 MPa. The stirring was continued for 2 hours while maintaining the internal temperature at 85 ° C. and the internal pressure at 5.5 MPa. After cooling, the autoclave was purged of gas and the contents were taken out. The reaction solution was filtered, washed with methanol several times, and dried under reduced pressure. The yield of polyketone is
The amount of 1.33 g and [η] was 3.80 dl / g. The catalyst activity at this time was 2.5 kg / g-Pd · hr, and the catalyst activity for the first hour was 2.2 kg / g-Pd.
・ Hr, catalytic activity in the latter half hour is 2.8 kg / g-P
It was d · hr, and it was confirmed that the high catalytic activity was maintained even in the latter half of the polymerization.

[0031]

COMPARATIVE EXAMPLE 1 In Example 1, 200 μmol of 1,4-benzoquinone was used instead of cupric chloride, and the reaction was carried out in the same manner as in Example 1. The content taken out by purging the autoclave is yellow with 1,4-benzoquinone, and in the same washing operation as in Example 1, 1,4-benzoquinone cannot be removed from the polymer, and further washing with methanol is required. If you don't repeat, it's a safe amount 1,
The 4-benzoquinone could not be removed. The yield of polyketone after drying under reduced pressure was 1.43 g, and [η] was
It was 4.40 dl / g. The catalyst activity at this time is 2.
The catalyst activity was 7 kg / g-Pd · hr, the catalyst activity in the first hour was 2.5 kg / g-Pd · hr, and the catalyst activity in the second hour was 2.9 kg / g-Pd · hr. .

[0032]

COMPARATIVE EXAMPLE 2 The procedure of Example 1 was repeated except that cupric chloride was not added, and the polyketone yield after drying under reduced pressure was 0.91 g, [η].
Was 4.05 dl / g. The catalytic activity at this time is
1.7 kg / g-Pd · hr, the catalytic activity in the first hour was 2.0 kg / g-Pd · hr, and the catalytic activity in the latter half hour was 1.5 kg / g-Pd · hr. Yes, the catalyst was deactivated in the latter half of the polymerization.

[0033]

Example 2 50 micromoles of palladium chloride and 60 micromoles of 1,3-bis {di (2-methoxyphenyl) phosphino} propane were dissolved in 2 ml of methanol. After complete dissolution, 1 mmol of sulfuric acid was added to the methanol solution, and then 1 mmol of cupric chloride was dissolved. This solution was diluted with methanol and water to prepare a diluted catalyst solution consisting of 4 ml of methanol and 1 ml of water.

5 g of a dry polyketone polymer of this diluted catalyst solution, carbon monoxide prepared beforehand, and ethylene
Was charged in a 2000 ml autoclave made of stainless steel and purged with nitrogen. After sealing the autoclave, the contents were heated with stirring, and when the internal temperature reached 85 ° C., an equimolar mixed gas of carbon monoxide and ethylene was added until the internal pressure of the autoclave reached 5.5 MPa. Inner temperature is 85
Stirring was continued for 2 hours while maintaining the internal pressure at 5.5 ° C and the internal pressure at 5.5 MPa. After cooling, the gas in the autoclave was purged and the contents were taken out. The reaction solution was filtered, washed with methanol several times, and dried under reduced pressure. The yield of polyketone obtained in addition to the initially charged polymer was 20.9 g, [η]
Was 4.10. The catalytic activity at this time is 2.0k
g / g-Pd · hr, the catalytic activity in the first hour is 1.8 kg / g-Pd · hr, and the catalytic activity in the latter half hour is 2.2 kg / g-Pd · hr, It was confirmed that the high catalytic activity was maintained in the latter half of the polymerization.

[0035]

Comparative Example 3 The procedure of Example 2 was repeated except that cupric chloride was not added during the preparation of the catalyst solution. The yield of polyketone obtained in addition to the initially charged polymer was , 15.4 g, [η] is 4.15.
Met. The catalyst activity at this time is 1.5 kg / g-Pd.
・ Hr, catalytic activity for the first hour is 1.8 kg
/ G-Pd · hr, the catalyst activity in the latter half hour is 1.2
It was kg / g-Pd · hr, and the catalyst was deactivated in the latter half of the polymerization. From the results of ¹³ C-NMR and IR, it was confirmed from the results of ¹³ C-NMR and IR that all the polymers obtained in Examples and Comparative Examples were polyketones substantially composed of a repeating unit derived from carbon monoxide and a repeating unit derived from ethylene. The above results are summarized in Table 1.

[0036]

[Table 1]

[0037]

Industrial Applicability According to the production method of the present invention, the polyketone yield per catalyst is high, and the polyketone can be produced efficiently and safely without lowering or deactivating the catalytic activity during polymerization.

Claims (14)

[Claims] 1. A catalyst of groups 9, 10 and 1
A metal complex composed of at least one transition metal compound (a) selected from Group 1 and a ligand (c) is used to produce a polyketone by copolymerizing carbon monoxide and an ethylenically unsaturated compound. A method for producing a polyketone, which comprises copolymerizing the transition metal in the presence of a metal compound (b) capable of being oxidized. 2. The method for producing a polyketone according to claim 1, wherein the metal compound (b) is a compound containing at least one metal selected from copper, iron, manganese, tungsten, molybdenum, aluminum, lithium and vanadium. . 3. The method for producing a polyketone according to claim 1, wherein the metal compound (b) is cupric chloride. 4. The method for producing a polyketone according to claim 1, wherein the transition metal compound (a) is a palladium compound. 5. The method for producing a polyketone according to claim 1, wherein 1.0 to 100 mol of the metal compound (b) is present per 1.0 mol of the compound (a) of the transition metal. 6. The catalysts of groups 9, 10 and 1
A metal complex comprising a compound (a) of at least one transition metal selected from Group 1, a ligand (c) and an anion (d) of an acid having a pKa of 4 or less is used. Item 2. A method for producing a polyketone according to Item 1. 7. The method for producing a polyketone according to claim 1, wherein the ligand (c) is a phosphorus bidentate ligand. 8. The ligand (c) is 1,3-bis {di (2
-Methoxyphenyl) phosphino} propane and / or 1,3-bis (diphenylphosphino) propane. 9. The anion (d) of an acid is an anion derived from at least one acid selected from sulfuric acid, trifluoroacetic acid and paratoluenesulfonic acid. Method for producing polyketone. 10. The metal compound (b) is obtained by oxidizing the metal compound (b) reduced by oxidizing at least one transition metal selected from Group 9, Group 10 and Group 11. The method for producing a polyketone according to claim 1, wherein the polyketone is reused. 11. The reduced metal compound (b),
11. The method for producing a polyketone according to claim 10, wherein the polyketone is oxidized by bringing it into contact with at least one selected from oxygen, an inorganic oxidizing agent and an organic oxidizing agent. 12. The method for producing a polyketone according to any one of claims 1 to 11, wherein carbon monoxide and an ethylenically unsaturated compound are copolymerized by suspension polymerization or gas phase polymerization. . 13. The method for producing a polyketone according to claim 1, wherein the polyketone is produced by a continuous polymerization method. 14. A polyketone obtained by the method according to any one of claims 1 to 13.