JPH0610167B2 - Process for producing fluorine-substituted aromatic carboxylic acid aryl ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a fluorine-substituted aromatic compound which is an important aromatic fluorine compound as an intermediate for monomers for heat-resistant polymers or intermediates for agricultural chemicals, pharmaceuticals, etc. It relates to a method for producing a carboxylic acid aryl ester.

(Prior Art) A fluorine-substituted aromatic carboxylic acid aryl ester is a method of reacting a fluorine-substituted aromatic carboxylic acid and an aromatic hydroxy compound with a dehydration condensation agent such as phosphorus oxychloride (Pharmaceutical Journal Vol. 78, Vol. 546 page, 1958), or by the reaction of a fluorine-substituted aromatic carboxylic acid chloride with an aromatic hydroxy compound. However,
Fluorine-substituted aromatic carboxylic acid or fluorine-substituted aromatic carboxylic acid chloride as these raw materials is expensive,
A dehydrating condensing agent such as phosphorus oxychloride is required in a stoichiometric amount, and its waste treatment is troublesome, which is a problem for industrial implementation.

On the other hand, it is also known that derivatives of bromobenzene or iodobenzene which are not substituted with fluorine react with carbon monoxide and phenol in the presence of a palladium catalyst and a base to give benzoic acid phenyl ester (JP Sho 59
-29641).

However, the reaction with fluorine-substituted aromatic halide carbon monoxide and aromatic hydroxy compounds, which are compounds in which fluorine and halogen different from fluorine are both directly bonded to the aromatic ring, are unknown and The influence of fluorine, which is the base, has never been known.
Therefore, as a result of continuous investigations by the present inventors to develop a method capable of producing a fluorine-substituted aromatic carboxylic acid aryl ester from a fluorine-substituted aromatic halide in high yield, palladium or a palladium compound and a phosphine compound were obtained. To react carbon monoxide and an aromatic hydroxy compound with fluorine and a fluorine-substituted aromatic halide in which halogen different from fluorine is directly bonded to an aromatic ring in the presence of a catalyst system consisting of Therefore, the inventors have found that the target fluorine-substituted aromatic carboxylic acid aryl ester can be obtained in high yield and high selectivity, and have previously filed a patent application (Japanese Patent Application No. 60-26596).

(Means and Action of Invention) As a result of further studies on this reaction, the present inventors have found that by using an alkali metal salt of an aromatic hydroxy compound as one reaction reagent, two different reaction reagents can be used. It was found that the desired fluorine-substituted aromatic carboxylic acid aryl ester can be obtained in high yield and high selectivity without using a base and an aromatic hydroxy compound.

That is, in the present invention, in the presence of a palladium catalyst and / or a Nickel catalyst, fluorine and a fluorine-substituted aromatic halide in which halogens different from fluorine are directly bonded to an aromatic ring are combined with carbon monoxide and aromatic hydroxy. A method for producing a fluorine-substituted aromatic carboxylic acid aryl ester, which comprises reacting with an alkali metal salt of a compound.

The method of the present invention is different from the one previously filed, and is characterized in that an aromatic hydroxy compound is not present in the carbonylation reaction system.

The palladium catalyst used in the present invention is not particularly limited as long as it contains a palladium element as a component,
Palladium may be in a metallic state or may be a component forming a compound. Further, this palladium component is, for example, activated carbon, graphite, silica, alumina, silica-alumina, silica-titania, titania, zirconia, barium sulfate, calcium carbonate, asbestos, bentonite, diatomaceous earth, polymer, ion exchange resin,
It may be supported on a carrier such as zeolite, molecular sieve, magnesium silicate or magnesia.

Examples of the palladium in the metallic state include palladium metal, palladium black, and a compound containing palladium ions supported on the carrier as described above, followed by reduction treatment with hydrogen, formaldehyde, hydrazine, or the like, and an alloy containing palladium or an intermetallic compound. Are used. Examples of alloys or intermetallic compounds include selenium, tellurium,
Sulfur, antimony, bismuth, copper, silver, gold, zinc, tin, vanadium, iron, cobalt, nickel, mercury, lead,
Examples thereof include those containing thallium, chromium, molybdenum, tungsten and the like. Of course, these alloys or intermetallic compounds may be supported on the carrier as described above.

On the other hand, as a compound containing palladium, PdCl ₂ ,
Inorganic salts such as PdBr ₂ , PdI ₂ , Pd (NO ₃ ) ₂ and PdSO ₄ ; Pd (OCOCH ₃ ) ₂ and organic acid salts such as palladium oxalate; Pd (CN) ₂ ; PdO; Pds; M ₂ [P
dX ₄ ], M ₂ [PdX ₆ ], palladium salts (M represents an alkali metal or an ammonium ion, and X represents a nitro group, a cyano group, or a halogen);
Ammine complexes of palladium such as [Pd (NH ₃ ) ₄ ] X ₄ and [Pd (en) ₂ ] X ₂ (X has the same meaning as above,
en represents ethylenediamine); PdCl ₂ (PhCN)
₂ , PdCl ₂ (PR ₃ ) ₂ , Pd (CO) (PR ₃ ) ₃ , Pd (PPh ₃ )
_{4, PdCl (R) (PPh} 3) 2, Pd (C 2 H 4) (PPh 3) 2, Pd
Complex compounds such as (C ₃ H ₅ ) ₂ or organometallic compounds (R represents an organic group); Complex compounds in which a chelate ligand such as Pd (acac) ₂ is coordinated (acac represents acetylacetone) Are used.

The nickel catalyst used in the present invention is not particularly limited as long as it contains a nickel element as a component, and nickel may be in a metallic state or may be a component forming a compound. Further, the nickel component may be supported on the carrier as described above.

On the other hand, as a compound containing nickel, NiCl ₂ , N
Halogenated nickels such as iBr ₂ and NiI ₂ ; Ni
SO ₄ , Ni (NO ₃ ) ₂ , NiCO ₃ , Ni (SCN) ₂ , Ni
Nickel salts of inorganic acids such as (ClO ₄ ) ₂ ; Ni (OCOC
H ₃ ) ₂ , nickel salts of organic acids such as nickel oxalate; nickel oxide; nickel hydroxide; nickel sulfide; nickel phosphide; nickel salts represented by M ₂ [NiX ₄ ] and M ₄ [NiX ₆ ] ( M represents an alkali metal or ammonium ion, X represents a nitro group, a cyano group, a halogen,
NO _3, 1 / 2SO represent _4); [Ni (NH _{3) 4] X} 2, [Ni _{(Y) 3] X 2,} [Ni _{(Y) 2] X 2,} [Ni (p
y) ₄ ] X _{2 and the} like nickel ammine complexes (X has the same meaning as above, Y represents a chelating ligand such as ethylenediamine, diethylenetriamine, bipyridine, and phenanthroline, and py represents pyridine); Ni
Complex compounds in which a chelate ligand such as (acac) ₂ is coordinated (acac represents acetylacetone); Ni (C
O) ₄ , Ni (CO) ₃ (PR ₃ ), Ni (CO) ₂ (PR ₃ ) ₂ , NiX ₂
(PR ₃ ) ₂ , NiX (PR ₃ ) ₃ , Ni (PR ₃ ) ₄ , NiXPh (PR
₃ ) ₂ , Ni (RNC) ₂ , [NiX (allyl) ₂ NiC ₅ H ₃ ) ₂ ,
_{Ni (CO) 2 (C 5} H 5) 2, NiX (C 5 H 5) (PR 3), Ni (CO
D) ₂ , complex compounds such as Ni (COD) (PR ₃ ), or organic nickel compounds (R represents an organic group such as alkyl and aryl, COD represents cyclooctadiene) and the like are used. Note that some of these compounds may be used in the form of hydrates.

These palladium catalysts and nickel catalysts may be used alone or in combination of two or more.

Further, other compounds can be added for the purpose of improving the yield and selectivity, increasing the reaction rate, and decreasing the reaction temperature. Examples of such a compound include a phosphine compound represented by the general formula (I).

P ▲ R ^′ ₁ R ^′ ₂ R ^′ ₃ ▼ (I) (wherein, ▲ R ^′ ₁ ▼, ▲ R ^′ ₂ ▼, ▲ R ^′ ₃ ▼ are hydrogen,
It represents a halogen, an aliphatic group, an alicyclic group, an aromatic group, or an araliphatic group, which may be the same or may be an element constituting a ring containing phosphorus. ) Of course, it may be a polyphosphine compound containing two or more such phosphorus in one molecule.

Examples of such phosphine compounds include n-octylphosphine, di-n-butylphosphine, diethylbutylphosphine, tri-n-propylphosphine,
Alkylphosphines such as tri-n-butylphosphine, dialkylphosphines and trialkylphosphines; cycloaliphatic phosphines such as cyclohexylphosphine and dicyclohexylphosphine; benzylphosphine, dibenzylphosphine, dibenzylethyl Aromatic aliphatic phosphines such as phosphine and tribenzylphosphine; methylphenylphosphine, ethylphenylphosphine, dimethylphenylphosphine, methyldiphenylphosphine, methylbenzylphenylphosphine,
Mixed phosphines such as ethyldiphenyl phosphine and dicyclohexyl phenyl phosphine; aryl phosphines such as phenyl phosphine, tolyl phosphine, diphenyl phosphine, triphenyl phosphine, tristril phosphine, diphenyl tryl phosphine Ins, diarylphosphines and triarylphosphines; bis (diphenylphosphino) methane, bis (diphenylphosphino) ethane, orthophenylene bis (diethylphosphine, 2,2'-bis (diphenylphosphine) )
Diphosphines such as -1,1'-binaphthyl are used.

Such phosphine compounds may be of one type or of two types.
You may use it in mixture of 2 or more types. Among such phosphine compounds, triarylphosphine is particularly preferably used. Among the triarylphosphines, triphenylphosphine is particularly preferably used because it is easily available.

The fluorine-substituted aromatic halide used as a raw material in the present invention is any aromatic compound in which fluorine as a substituent and halogen different from fluorine are both directly bonded to an aromatic ring. Good. Examples of such fluorine-substituted aromatic halides include benzene,
One or more fluorine atoms in the aromatic ring of aromatic hydrocarbons such as toluene, xylene, ethylbenzene, diethylbenzene, propylbenzene, quinene, trimethylbenzene, tetramethylbenzene, naphthalene, and anthracene, and one or more other halogens. Compounds substituted by a hydrogen atom of the aromatic ring of a heteroaromatic compound such as pyridine, quinoline, bipyridine, etc., by one or more fluorine atoms and one or more other halogen atoms; formula [However, A is a simple bond, or -O-, -S-,-
SO ₂ −, —CO—, —CH ₂ —, —C (R) ₂ — (where R is a lower alkyl group) represents a divalent group] And compounds substituted by one or more fluorine and one or more other halogen. Particularly preferred halogen is
It is bromine or iodine.

In these fluorine-substituted aromatic halides, other substituents that do not adversely affect the reaction, for example, a lower alkyl group, a lower alkoxy group, an ester group, a nitro group, a cyano group, etc. It may be one that has been used.

Among such fluorine-substituted aromatic halides, benzene derivatives are particularly preferably used, and examples thereof include fluorochlorobenzene (each isomer), fluorobromobenzene (each isomer), fluoroiodobenzene (each isomer). Isomers) and other monofluoromonohalogenated benzenes; fluorodichlorobenzene (each isomer), fluorodibromobenzene (each isomer), fluorodiiodobenzene (each isomer), monofluorotribromobenzene (each isomer) Isomers), monofluorotriiodobenzene (each isomer), monofluorotetrabromobenzene (each isomer), etc. monofluoropolyhalogenated benzenes; difluorochlorobenzene (each isomer), difluorobrombenzene (each isomer) Body), difluoroiodobenzene (each isomer), trifluoro Polyfluoromonohalogenated benzenes such as bromobenzene (each isomer) and pentafluorobrombenzene (each isomer); difluorodichlorobenzene (each isomer), difluorodibromobenzene (each isomer), difluorodiiodo Examples thereof include polyfluoropolyhalogenated benzenes such as benzene (each isomer), difluorotribromobenzene (each isomer), and trifluorodibromobenzene (each isomer).

Among these benzene derivatives, parafluorobromobenzene and parafluoroiodobenzene are particularly preferably used.

The alkali metal salt of an aromatic hydroxy compound used in the present invention is a compound in which the hydrogen atom of the hydroxyl group of the aromatic hydroxy compound is replaced by an alkali metal atom. Although such a compound may be obtained by any method, it can be easily obtained from, for example, a basic substance containing an alkali metal atom and an aromatic hydroxy compound. Examples of the basic substance containing an alkali metal atom include alkali metals, alkali metal oxides, alkali metal hydroxides, alkali metal carbonates and alkali metal bicarbonates. In particular, the method by the reaction of an aromatic hydroxy compound with an alkali metal hydroxide such as lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide or cesium hydroxide is the easiest.

As such an aromatic hydroxy compound, any compound may be used as long as the hydroxyl group is directly bonded to the aromatic group. For example, phenol; cresol (each isomer), xylenol (each isomer), trimethylphenol (each isomer), tetramethylphenol (each isomer), ethylphenol (each isomer), propylphenol (each isomer) Various alkylphenols such as; methoxyphenol (each isomer), ethoxyphenol (each isomer), various alkoxyphenols; Formula (However, A is as described above, and the aromatic ring may be substituted with a substituent such as a lower alkyl group, a lower alkoxy group, an ester group, a nitro group, and a cyano group.) Heteroaromatic hydroxyl compounds such as naphthol (each isomer) and various substituted naphthols; hydroxypyridine (each isomer), hydroxycoumarin (each isomer), hydroxyquinoline (each isomer); hydroquinone, resorcin, catechol, Aromatic dihydroxy compounds such as naphthohydroquinone, anthrahydroquinone, and their alkyl-substituted dihydroxy compounds; Formulas (However, A is as described above, and the aromatic ring may be substituted with a substituent such as a lower alkyl group, a lower alkoxy group, an ester group, a nitro group, or a cyano group.) Kind and the like.

Particularly preferable alkali metal salts of aromatic hydroxy compounds are alkali metal salts of phenol and 2,6-dimethylphenol, and sodium and potassium are particularly preferable as the alkali metal species.

The reaction of the present invention will be illustrated by the following reaction formula when the case of an alkali metal salt of parafluorohalogenobenzene and phenol is illustrated.

(X represents Cl, Br, I, and M represents an alkali metal atom.) Thus, one of the features of the method of the present invention is that only halogen different from fluorine is substituted with an aryloxycarbonyl group. That is, the fluorine can be left without being replaced. It has been found that fluorine may not adversely affect this esterification reaction, or rather, it may have a favorable effect in terms of yield, selectivity and reaction rate.

In carrying out the present invention, the palladium catalyst and / or the nickel catalyst are usually used as these metal atoms in an amount of 0.0001 to 1000 times mol based on the fluorine-substituted aromatic halide.

The alkali metal salt of the aromatic hydroxy compound may not be used in a particularly limited amount with respect to the fluorine-substituted aromatic halide, but is preferably 0.5 to 2.0 equivalents, more preferably 0.8 to 1.5 equivalents. Is.

The carbon monoxide may be pure carbon monoxide, or may be diluted with another gas such as nitrogen, argon, helium, or lower hydrocarbon that does not adversely affect the reaction. Carbon monoxide has a partial pressure of 0.1 to 300 Kg / cm ³ , preferably 1 to 200 Kg / c.
Used in the m ³ range.

The method of the present invention can be carried out without using a reaction solvent, but it is a preferable method to use a solvent that does not adversely affect the reaction. Examples of such a solvent include aliphatic hydrocarbons such as hexane, heptane, octane, decane, and pentadecane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; aromatics such as benzene, toluene, xylene, and mesitylene. Hydrocarbons; Nitriles such as acetonitrile and benzonitrile; Sulfones such as sulfolane, metal sulfolane and dimethyl sulfolane; Ethers such as tetrahydrofuran, 1,4-dioxane and 1,2-dimethoxyethane; Ketones such as acetone and methyl ethyl ketone Esters such as ethyl acetate and ethyl benzoate; amides such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone and hexamethylphosphoramide.

The reaction of the present invention is usually 50 to 350 ° C., preferably 100 to 300.
The reaction is carried out in the range of 0 ° C. and the reaction pressure is usually 1 to 500 Kg / cm ³ , preferably 5 to 300 Kg / cm ³ .

Further, the reaction time is usually several minutes to several tens hours, though it varies depending on the type and amount of the catalyst system used and the other reaction conditions such as temperature and pressure.

As the reaction system, any of a batch system, a continuous system and a combination thereof may be adopted.

(Effect of the Invention) By the method of the present invention, a fluorine-substituted carboxylic acid aryl ester is produced from a fluorine-substituted aromatic halide and an alkali metal salt of carbon monoxide and an aromatic hydroxy compound in high yield and high selectivity. I was able to do it.

This fluorine-substituted aromatic carboxylic acid aryl ester is
Not only used as an intermediate for pesticides and medicines,
Some of these compounds, such as parafluorobenzoic acid phenyl ester and parafluorobenzoic acid 2,6-dimethylphenyl ester, are precursors of monomers for aromatic polyether ketones having excellent heat resistance and hot water resistance. As important as. That is, these esters are converted to 4- (parafluorobenzoyl) phenol and 4- (parafluorobenzoyl) -2,6- by a rearrangement reaction, respectively.
This is because they can be easily converted into dimethylphenol, and these phenol derivatives can be used by themselves or as one component of the copolymer, as a monomer of the aromatic polyetherketone.

(Examples) Hereinafter, the present invention will be further described with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Parafluorobromobenzene 50 mmol, phenol and an equivalent amount of sodium hydroxide were reacted in an aqueous solution, and then dehydrated and dried to obtain sodium phenoxide 60 mmol, nickel acetylacetone Ni (acac) ₂ 2.5 mmol, toluene 3
5 g was placed in an autoclave, the inside of the autoclave was replaced with carbon monoxide, and then carbon monoxide was injected under pressure of 50 kg / cm ³ . After reacting at 250 ° C. for 1 hour under stirring, then cooling,
As a result of analysis of the reaction solution, the reaction rate of parafluorobrombenzene was 94%, and the yield of phenyl ester of parafluorobenzoic acid was 82% with a selectivity of 87%.

Example 2 The procedure of Example 1 was repeated except that 50 mmol of parafluoroiodobenzene was used instead of parafluorobromobenzene and the reaction was carried out at 200 ° C. for 2 hours. As a result, the reaction rate of parafluoroiodobenzene was 95%. Thus, parafluorobenzoic acid phenyl ester was obtained with a yield of 93% and a selectivity of 98%.

Example 3 Nickel chloride NiC instead of nickel acetylacetone
The reaction was carried out in the same manner as in Example 2 except that the reaction was carried out at 220 ° C. using 2.5 mmol of l ₂ 2.5 mmol and 5 mmol of triphenylphosphine. As a result, the yield of parafluorobenzoic acid phenyl ester was 86% and the selectivity was Obtained in 86%.

Example 4 Sodium-2,6-instead of sodium phenoxide
Example 2 except that 60 mmol of dimethylphenoxide was used.
As a result of carrying out the reaction by the same method as described above, 2,6-dimethylphenyl ester of parafluorobenzoic acid was obtained with a yield of 94% and a selectivity of 97%.

In addition, sodium-2,6-dimethylphenoxide is
A product obtained by reacting 2,6-dimethylphenol with an equivalent amount of sodium hydroxide in an aqueous solution, dehydrated and dried was used.

Example 5 50 mmol of parafluorobromobenzene, 50 mmol of sodium phenoxide, 0.5 mmol of palladium chloride, 1 mmol of triphenylphosphine and 30 g of xylene were placed in an autoclave, and the inside of the autoclave was replaced with carbon monoxide. Pressed into / cm ³ . 220 ° C under stirring
After reacting for 2 hours at room temperature, it was cooled and the reaction mixture was analyzed. As a result, the reaction rate of parafluorobromobenzene was 98%, and the yield of parafluorobenzoic acid phenyl ester was 97% and the selectivity was 99%. It was

Example 6 4-Fluoro-instead of parafluorobromobenzene
The reaction was performed in the same manner as in Example 5 except that 50 m of 4'-iodobiphenyl was used, and as a result, 4- (parafluorophenyl) benzoic acid phenyl ester was obtained with a yield of 97% and a selectivity of 98%. It was

Example 7 2-Fluoro-4 instead of parafluorobromobenzene
-Using 50 mmol of chlorotoluene, 70 kg / cm ^{3 of} carbon monoxide
Under the same procedure as in Example 5 except that the mixture was pressed into
As a result of reacting at 240 ° C. for 5 hours, 3-fluoro-4-methylbenzoic acid phenyl ester was obtained with a yield of 60% and a selectivity of 75%.

Example 8 Sodium-2,6-instead of sodium phenoxide
Example 5 except that 60 mmol of dimethylphenoxide was used.
As a result of carrying out the reaction in the same manner as described above, 2,6-dimethylphenyl ester of parafluorobenzoic acid was obtained with a yield of 97% and a selectivity of 99%.

Example 9 Using 60 mmol of sodium-1-naphthoxide instead of sodium phenoxide, the reaction was carried out in the same manner as in Example 2. As a result, parafluorobenzoic acid naphthyl ester was obtained in a yield of 96% and a selectivity of 98%. Was obtained.

Example 10 2-Fluoro-6 instead of parafluorobromobenzene
As a result of carrying out the reaction in the same manner as in Example 2 except that 50 mmol of iodonaphthalene was used, 2-fluoronaphthalene-6-carboxylic acid phenyl ester was obtained with a yield of 96% and a selectivity of 97%.

Example 11 Except that 60 mmol of potassium phenoxide obtained by mixing, dehydrating, and drying phenol and an equivalent amount of potassium hydroxide in a carboxylic acid of sodium phenoxide in an aqueous solution is used,
As a result of carrying out the reaction in the same manner as in Example 2, parafluorobenzoic acid phenyl ester was obtained with a yield of 95% and a selectivity of 98%.

Example 12 Potassium phenoxide instead of sodium phenoxide
As a result of carrying out the reaction in the same manner as in Example 5 except that 60 mmol was used, parafluorobenzoic acid phenyl ester was obtained with a yield of 97% and a selectivity of 98%.

Example 13 Potassium obtained by mixing, dehydrating and drying an aqueous solution of 2,6-dimethylphenol and an equivalent amount of potassium hydroxide in place of sodium-2,6-dimethylphenoxide-
Other than using 60 mmol of 2,6-dimethylphenoxide,
The reaction was carried out in the same manner as in Example 4, and as a result, parafluorobenzoic acid 2,6-dimethylphenyl ester was obtained in a yield of 95.
%, Selectivity 98%.

Example 14 A reaction was carried out in the same manner as in Example 2 except that 60 mmol of lithium phenoxide obtained by mixing, dehydrating and drying an aqueous solution of phenol and lithium hydroxide was used instead of sodium phenoxide. As a result, parafluorobenzoic acid phenyl ester was obtained with a yield of 95% and a selectivity of 97%.

Examples 15 to 19 Using 50 mmol of parafluorobromobenzene, 50 mmol of sodium phenoxide and 30 g of xylene, the reaction was carried out in the same manner as in Example 5 under the conditions (catalyst, additive, reaction temperature, time) shown in Table 1. I went.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B01J 31/28 X 7821-4G C07C 67/36 69/78 9279-4H // C07B 61/00 300

Claims (7)

[Claims] 1. A fluorine-substituted aromatic halide in which fluorine and halogen different from fluorine are directly bonded to an aromatic ring in the presence of a palladium catalyst and / or a nickel catalyst, carbon monoxide and an aromatic hydroxy compound. A process for producing a fluorine-substituted aromatic carboxylic acid aryl ester, which comprises reacting with an alkali metal salt of. 2. The method according to claim 1, wherein the halogen different from fluorine is bromine or iodine. 3. A fluorine-substituted aromatic halide in which fluorine and halogen different from fluorine are both directly bonded to an aromatic ring are fluorine and benzene derivatives having halogen different from fluorine as a substituent. The method according to claim 1. 4. The method according to claim 3, wherein the benzene derivative is parafluorobromobenzene or parafluoroiodobenzene. 5. The method according to any one of claims 1 to 4, wherein the aromatic hydroxy compound is an aromatic monohydroxy compound. 6. The method according to claim 5, wherein the aromatic hydroxy compound is phenol and / or 2,6-dimethylphenol. 7. The method according to claim 1, wherein a phosphine compound is used as an additional cocatalyst.