JP2022155527A - Method for producing olefin copolymer and transition metal compound - Google Patents

Abstract

To provide a method that can efficiently produce a cyclic olefin copolymer containing an aromatic structure, and a novel transition metal compound suitable as a component of a catalyst for olefin polymerization in the production method.SOLUTION: A method includes copolymerizing an ethylene, an aliphatic cyclic olefin, and a cyclic olefin containing an aromatic structure in the presence of a catalyst for olefin polymerization containing a transition metal compound represented by, for example, formula (1) and at least one compound selected from the group consisting of an organic metal compound, an organic aluminum oxy compound, and a compound reactable with the transition metal compound to form an ion pair.SELECTED DRAWING: None

Description

The present invention relates to a method for producing an olefin copolymer. The present invention also relates to novel transition metal compounds.

Conventionally, a catalyst comprising a metallocene compound and a cocatalyst such as an organoaluminumoxy compound is known as a catalyst for producing an olefin polymer such as an ethylene/α-olefin copolymer.

Various types of transition metal compounds such as metallocene compounds have been actively developed. For example, Patent Document 1 discloses a transition metal compound (A) represented by the following general formula:

(In the formula, M represents a transition metal of Group 4 of the periodic table such as Ti, L represents a monovalent anionic ligand whose coordinated atom is an element of Group 15 of the periodic table, and X represents a halogen, etc. , m represents an integer of 1 to 3, and R ¹ to R ⁵ represent hydrogen, halogen, an alkyl group having 1 to 20 carbon atoms, or the like.)
and ethylene and/or an α-olefin having 3 to 20 carbon atoms and at least one cyclic A method for producing a cyclic olefin copolymer by copolymerization with an olefin compound is described, and specific examples of the transition metal compound (A) include CpTi(t-Bu ₂ C═N)Cl ₂ and Cp ^* Ti. (2,6- ⁱ Pr ₂ PhO)Cl ₂ is mentioned. (Cp represents a cyclopentadienyl group, and Cp ^* represents an η ⁵ -pentamethylcyclopentadienyl group).

Further, Non-Patent Document 1 describes that ethylene and norbornene or the like were copolymerized in the presence of a transition metal compound represented by the following formula and methylaluminoxane (MAO).

Further, it has been reported that a copolymer of ethylene, an alicyclic cyclic olefin, and a cyclic olefin containing an aromatic structure is suitable for lens resins and the like. (For example, Patent Document 2)

Japanese Patent Application Laid-Open No. 2007-63409 WO2019/107363

Macromolecules 2011, 44, 1986-1998

The transition metal compound described in Non-Patent Document 1 as a metallocene compound is considered to be suitable for a copolymer of ethylene, an alicyclic cyclic olefin, and a cyclic olefin containing an aromatic structure. However, the inventors' studies have shown that the polymerization activity and the molecular weight of the resulting polymer are not sufficient. This is because the use of a cyclic olefin containing an aromatic structure has an electronic effect derived from the aromatic structure on the active site derived from the transition metal compound, which reduces the polymerization rate and relatively increases the chain transfer rate. was considered a possibility.

Accordingly, an object of the present invention is to provide a suitable method for producing a copolymer of ethylene, an alicyclic cyclic olefin, and a cyclic olefin containing an aromatic structure. Another object of the present invention is to provide a transition metal compound that is preferably suitable for the production method described above.

The present invention relates to, for example, the following [1] to [8].
[1]
(A) a transition metal compound represented by the following general formula [A] and (B) (B-1) an organometallic compound,
The presence of an olefin polymerization catalyst containing (B-2) an organoaluminumoxy compound and (B-3) at least one compound selected from the group consisting of compounds that form an ion pair by reacting with the transition metal compound. Below is a method for producing an olefin copolymer by copolymerizing ethylene, an alicyclic cyclic olefin, and a cyclic olefin containing an aromatic structure.

〔式［Ａ］において、
Ｍはチタン原子、ジルコニウム原子、またはハフニウム原子であり、
ｎは１～４の整数であり、
Ｘはそれぞれ独立に水素原子、ハロゲン原子、炭化水素基、ハロゲン含有基、ケイ素含有基、酸素含有基、イオウ含有基、窒素含有基、リン含有基、ホウ素含有基、アルミニウム含有基、またはジエン系二価誘導体基であり、
Ｒ^{1`</sup>～Ｒ<sup>8`}はそれぞれ独立に水素原子、炭素原子数１～２０の炭化水素基、ハロゲン原子、ハロゲン含有基、ケイ素含有基、酸素含有基、窒素含有基、イオウ含有基、またはリン含有基であり、
Ｒ^{1`</sup>～Ｒ<sup>5`}のうち隣接する基同士は互いに結合して環を形成していてもよく、
Ｒ^{6`</sup>～Ｒ<sup>8`}の少なくとも１つは３級炭化水素基である。〕

[In formula [A],
M is a titanium atom, a zirconium atom, or a hafnium atom;
n is an integer from 1 to 4,
Each X is independently a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, an aluminum-containing group, or a diene is a divalent derivative group,
R ^{1 '} to R ^{8 '} are each independently a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a nitrogen-containing group, a sulfur-containing group, or a phosphorus is a containing group;
Adjacent groups among R ^{1` to R 5` may} be bonded to each other to form a ring,
At least one of R ⁶ ' to R ⁸ ' is a tertiary hydrocarbon group. ]

[2]
The method for producing the olefin copolymer of the above [1], wherein in the general formula [A], M is a titanium atom.

[3]
The method for producing an olefin copolymer according to the above [1], wherein in the general formula [A], R 1 ^' is a hydrocarbon group having 1 to 20 carbon atoms, and R ^{2 '} to R ^{5 '} are hydrogen atoms.

[4]
In the general formula [A], at least one of R ⁶ ' to R ⁸ ' is a substituent selected from an aryl group having 6 to 20 carbon atoms or a substituted aryl group. Production method.

[5]
A transition metal compound represented by the following general formula [A-1].

〔式［Ａ－１］において、
Ｍはチタン原子、ジルコニウム原子、またはハフニウム原子であり、
ｎは１～４の整数であり、
Ｘはそれぞれ独立に水素原子、ハロゲン原子、炭化水素基、ハロゲン含有基、ケイ素含有基、酸素含有基、イオウ含有基、窒素含有基、リン含有基、ホウ素含有基、アルミニウム含有基、またはジエン系二価誘導体基であり、
Ｒ^{1`</sup>～Ｒ<sup>8`}はそれぞれ独立に水素原子、炭素原子数１～２０の炭化水素基、ハロゲン原子、ハロゲン含有基、ケイ素含有基、酸素含有基、窒素含有基、イオウ含有基、またはリン含有基であり、
Ｒ^{1`</sup>～Ｒ<sup>5`}のうち隣接する基同士は互いに結合して環構造を形成していてもよく、
Ｒ^{1`</sup>～Ｒ<sup>5`}のうち隣接する基同士が互いに結合して環構造を形成する場合は、前記環構造は脂環構造であり、
Ｒ^{6`</sup>～Ｒ<sup>8`}の少なくとも１つは３級炭化水素基である。〕

[In the formula [A-1],
M is a titanium atom, a zirconium atom, or a hafnium atom;
n is an integer from 1 to 4,
Each X is independently a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, an aluminum-containing group, or a diene is a divalent derivative group,
R ^{1 '} to R ^{8 '} are each independently a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a nitrogen-containing group, a sulfur-containing group, or a phosphorus is a containing group;
Adjacent groups among R ^{1` to R 5` may} be bonded to each other to form a ring structure,
When adjacent groups among R 1 ^′ to R ⁵ ′ are bonded to each other to form a ring structure, the ring structure is an alicyclic structure,
At least one of R ⁶ ' to R ⁸ ' is a tertiary hydrocarbon group. ]

[6]
The transition metal compound of the above [5], wherein in the general formula [A-1], M is a titanium atom.

[7]
The transition metal compound according to the above [5], wherein in the general formula [A-1], R 1 ' is a ^hydrocarbon group having 1 to 20 carbon atoms, and R ^{2 '} to R ⁵ ' are hydrogen atoms.

[8]
In the general formula [A-1], the transition metal of [5], wherein at least one of R ⁶ ' to R ⁸ ' is a substituent selected from an aryl group having 6 to 20 carbon atoms or a substituted aryl group. Compound.

By using the method for producing an olefin copolymer of the present invention, a polymer having a high molecular weight can be produced with relatively high activity.
Moreover, the transition metal compound used in the method for producing the olefin copolymer of the present invention includes novel compounds.

Hereinafter, the method for producing the olefin copolymer, the transition metal compound, etc. according to the present invention will be described in more detail.
[Transition metal compound]
The transition metal compound (A) used in the method for producing an olefin copolymer of the present invention is represented by the following general formula [A].

Moreover, the transition metal compound (A-1) having a specific structure among the transition metal compounds (A) is a novel compound.
[Transition metal compound (A)]
First, the transition metal compound (A) will be described.

《M》
In formula [A], M represents a titanium atom, a zirconium atom, or a hafnium atom, preferably a titanium atom or a zirconium atom, more preferably a titanium atom.

《R ^{1`</sup> ~ R <sup>8`} 》
In formula [A], R ^{1 '} to R ^{8 '} are each independently a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a nitrogen-containing group, It is a sulfur-containing group or a phosphorus-containing group, and adjacent groups among R 1 ^' to R ⁵ ' may be bonded to each other to form a ring.

Examples of the halogen atoms include fluorine, chlorine, bromine and iodine.
Examples of the hydrocarbon group include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, neopentyl, n-hexyl, etc. having 1 to 20 carbon atoms, preferably 1 to 10 linear or branched alkyl groups;
linear or branched alkenyl groups having 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms, such as vinyl, allyl, isopropenyl;
linear or branched alkynyl groups having 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms such as ethynyl and propargyl;
cyclic saturated hydrocarbon groups having 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and adamantyl;
cyclic unsaturated hydrocarbon groups having 5 to 20 carbon atoms such as cyclopentadienyl, indenyl and fluorenyl;
Aryl groups having 6 to 20 carbon atoms, preferably 6 to 10 carbon atoms such as phenyl, benzyl, naphthyl, biphenyl, terphenyl, phenanthryl, anthracenyl; and tolyl, iso-propylphenyl, t-butylphenyl, dimethylphenyl, di -Alkyl-substituted aryl groups such as t-butylphenyl.

Also included are those in which the hydrogen atoms of the above-exemplified hydrocarbon groups are substituted with hydrocarbon groups, such as aryl group-substituted alkyl groups such as benzyl and cumyl.
Examples of the cyclopentadienyl moiety having a ring formed by bonding adjacent groups among R 1 ^' to R ⁵ ' include the following ring structures, and the ring structures further include substituents. may have.

Among the structures having a ring formed by bonding to each other as described above, the structure having an alicyclic structure is an embodiment of the compound represented by the formula [A-1] of the present invention, which will be described later. It is a structure possessed by a compound.

In the present invention, when the structure is as described above, the polymerization activity tends to be relatively high, and the molecular weight of the resulting polymer tends to increase.
Examples of the halogen-containing groups include halogenated hydrocarbon groups having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms such as trifluoromethyl, pentafluorophenyl and chlorophenyl.

Examples of said silicon-containing groups include silyl groups, siloxy groups, hydrocarbon-substituted silyl groups, and hydrocarbon-substituted siloxy groups. Specific examples of hydrocarbon-substituted silyl groups among these include methylsilyl, dimethylsilyl, trimethylsilyl, ethylsilyl, diethylsilyl, triethylsilyl, diphenylmethylsilyl, triphenylsilyl, dimethylphenylsilyl, dimethyl-t-butylsilyl, dimethyl(pentafluoro phenyl)silyl and the like. Among these, methylsilyl, dimethylsilyl, trimethylsilyl, ethylsilyl, diethylsilyl, triethylsilyl, dimethylphenylsilyl, triphenylsilyl and the like are preferred. Trimethylsilyl, triethylsilyl, triphenylsilyl and dimethylphenylsilyl are particularly preferred. Specific examples of hydrocarbon-substituted siloxy groups include trimethylsiloxy and the like.

Examples of said oxygen-containing groups include alkoxy groups, aryloxy groups, ester groups, ether groups, acyl groups, carboxyl groups, carbonate groups, hydroxy groups, peroxy groups, carboxylic anhydride groups, and furyl groups.

Among oxygen-containing groups, preferred examples of alkoxy groups include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, and tert-butoxy,
Preferred examples of aryloxy groups include phenoxy, 2,6-dimethylphenoxy and 2,4,6-trimethylphenoxy,
Preferred examples of ester groups include acetyloxy, benzoyloxy, methoxycarbonyl, phenoxycarbonyl, and p-chlorophenoxycarbonyl;
Preferred examples of acyl groups include formyl, acetyl, benzoyl, p-chlorobenzoyl, and p-methoxybenzoyl groups.

Examples of the sulfur-containing group include a mercapto group, a thioester group, a dithioester group, an alkylthio group, an arylthio group, a thioacyl group, a thioether group, a thiocyanate group, an isothiocyanate group, a sulfoneester group, a sulfonamide group, Thiocarboxyl groups, dithiocarboxyl groups, sulfo groups, sulfonyl groups, sulfinyl groups, and sulfenyl groups are included.

Among sulfur-containing groups, preferred examples of thioester groups include acetylthio, benzoylthio, methylthiocarbonyl, and phenylthiocarbonyl.
Preferred examples of alkylthio groups include methylthio and ethylthio,
Preferred examples of arylthio groups include phenylthio, methylphenylthio, naphthylthio,
Preferred examples of sulfone ester groups include methyl sulfonate, ethyl sulfonate, phenyl sulfonate,
Preferred examples of sulfonamide groups include phenylsulfonamide, N-methylsulfonamide, N-methyl-p-toluenesulfonamide.

Examples of the nitrogen-containing group include an amino group, an imino group, an amide group, an imide group, a pyrrolidino group, a hydrazino group, a hydrazono group, a nitro group, a nitroso group, a cyano group, an isocyano group, a cyanate ester group, an amidino group, Ammonium salts of diazo groups and amino groups are included.

Among nitrogen-containing groups, preferred examples of amino groups include dimethylamino, ethylmethylamino, and diphenylamino,
Preferred examples of imino groups include methylimino, ethylimino, propylimino, butylimino, and phenylimino,
Preferred examples of amide groups include acetamide, N-methylacetamide, and N-methylbenzamide,
Preferred examples of imido groups include acetimido and benzimide.
Examples of said phosphorus-containing groups include phosphide groups, phosphoryl groups, thiophosphoryl groups, and phosphato groups.

( ^{R1`</sup> to <sup>R5`} )
One or more of R 1 ^' to R ⁵ ' are in particular carbon atoms such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, neopentyl, n-hexyl linear or branched alkyl groups of number 1 to 20, preferably 1 to 10;
aryl groups having 6 to 20 carbon atoms, preferably 6 to 10 carbon atoms such as phenyl, naphthyl, biphenyl, terphenyl, phenanthryl, anthracenyl;
One or more hydrogen atoms of these aryl groups are hydrocarbon groups having 1 to 20 carbon atoms such as substituted aryl groups substituted with halogen atoms, alkyl groups, alkoxy groups, aryl groups or aryloxy groups. preferable.

It is also preferred that at least one of R 1 ^' to R ⁵ ' is a hydrogen atom. In the present invention, a hydrogen atom refers to hydrogen as a substituent represented by H-.
Among the above embodiments, it is ^preferred that R 1 ' is a hydrocarbon group having 1 to 20 carbon atoms and R ^{2 '} to R ^{5 '} are hydrogen atoms. The above R ¹ ' is preferably selected from a secondary hydrocarbon group and a tertiary hydrocarbon group, particularly preferably a tertiary hydrocarbon group.

( ^{R6`</sup> to <sup>R8`} )
In formula [A], one or more of R ⁶ ' to R ⁸ ' is a tertiary hydrocarbon group. Such a hydrocarbon group is a tertiary hydrocarbon group having 4 to 20 carbon atoms, and specifically includes t-butyl group, t-pentyl group, t-hexyl group, adamantyl group, 1,1- A dimethylbenzyl group and the like can be mentioned. Of course, the tertiary hydrocarbon group may have a structure containing halogen, silicon, oxygen, nitrogen, sulfur and phosphorus. Preferred are so-called heteroatom-free tertiary hydrocarbon groups as described above.

Among the above, R ^{6 '} and/or R ^{7 '} are preferably tertiary hydrocarbon groups. Moreover, it is preferable that two or more are tertiary hydrocarbons. In particular, both R ⁶ ' and R ⁷ ' are preferably tertiary hydrocarbon groups.

In formula [A], in addition to the above requirements, at least one of R ⁶ ' to R ⁸ ' is preferably a substituent selected from an aryl group having 6 to 20 carbon atoms or a substituted aryl group. . Specifically, an aryl group having 6 to 20 carbon atoms, preferably 6 to 10 carbon atoms such as phenyl, benzyl, naphthyl, biphenyl, terphenyl, phenanthryl and anthracenyl, and substituents such as hydrocarbon groups and oxygen-containing groups. The aryl group having the above can be mentioned. Specific examples of the substituent are the same as the hydrocarbon group and oxygen-containing group described above. Among these, the hydrocarbon group is preferably a tertiary hydrocarbon group such as t-butyl group, t-pentyl group, t-hexyl group and dimethylbenzyl group, and the oxygen-containing group is methoxy group and ethoxy group. , n-propoxy, isopropoxy, n-butoxy, isobutoxy and tert-butoxy are preferred. Among the above aryl groups, substituted aryl groups are preferred, and aryl groups having a tertiary hydrocarbon group are particularly preferred.

When R ^{6 '} to R ⁸ ' contain such an aryl group or substituted aryl group, copolymers with a high content of structural units derived from cyclic olefins are produced by the copolymerization reaction between olefins and cyclic olefins, which will be described later. Polymers may be readily available and tend to be of relatively high molecular weight. For this reason, the above aspect is preferable when providing a material having a high glass transition temperature and excellent strength.

《n》
In formula [A], n is an integer of 1 to 4, and is selected depending on the valence of M and the type of X so that the transition metal compound (A) as a whole is electrically neutral.

《X》
In formula [A], each X is independently a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, aluminum It is a containing group or a diene-based divalent derivative group.

Specific embodiments of these halogen atoms, hydrocarbon groups, halogen-containing groups, silicon-containing groups, oxygen-containing groups, sulfur-containing groups, nitrogen-containing groups, and phosphorus-containing groups are the above-described R ^{1 '} to R ^{5 '} and Specific embodiments of the halogen atom, hydrocarbon group, halogen-containing group, silicon-containing group, oxygen-containing group, sulfur-containing group, nitrogen-containing group and phosphorus-containing group as R ⁸ ' are the same.

Examples of the boron-containing groups include boranediyl, boranetriyl, diboranyl, and groups such as alkyl-substituted boron, aryl-substituted boron, boron halide, and alkyl-substituted boron halide.

Examples of alkyl-substituted boron are represented by (Et) _2B- , (iPr) _2B- , (iBu) _2B- , (Et) _3B , (iPr) _3B , or (iBu) _3B . and
Examples of aryl-substituted boron include ( _C6H5 ) _2B- , _{( C6H5} ) _3B , _{( C6F5} ) _3B , or ( _{3,5- ( CF3} ) _2C6 a group represented by H ₃ ) ₃ B,
Examples of boron halides include groups represented by BCl ₂ — or BCl ₃ ,
Examples of alkyl group-substituted boron halides include groups represented by (Et)BCl-, (iBu)BCl- and (C ₆ H ₅ ) ₂ BCl. Of these, trisubstituted boron may be in a coordinated state. Here, Et represents an ethyl group, iPr represents an isopropyl group, and iBu represents an isobutyl group.

Examples of the aluminum-containing group include groups such as alkyl group-substituted aluminum, aryl group-substituted aluminum, halogenated aluminum, and alkyl group-substituted aluminum halide.

Examples of alkyl-substituted aluminum are represented by (Et) ₂ Al-, (iPr) ₂ Al-, (iBu) ₂ Al-, (Et) ₃ Al, (iPr) ₃ Al, or (iBu) ₃ Al. and
Examples of aryl group-substituted aluminum include groups represented by (C ₆ H ₅ ) ₂ Al-,
Examples of aluminum halides include groups represented by AlCl ₂ — or AlCl ₃ ,
Examples of alkyl group-substituted aluminum halides include groups represented by (Et)AlCl-- and (iBu)AlCl--. Of these, trisubstituted aluminum may be in a coordinated state. Here, Et represents an ethyl group, iPr represents an isopropyl group, and iBu represents an isobutyl group.

Examples of the diene-based divalent derivative groups include a 1,3-butadienyl group, an isoprenyl (2-methyl-1,3-butadienyl) group, a piperylenyl (1,3-pentadienyl) group, a 2,4-hexadienyl group, metallocyclopentene groups such as 1,4-diphenyl-1,3-pentadienyl group and cyclopentadienyl group;

Further, X may have a structure in which the groups listed as specific examples of X are bonded to each other and form a ring together with M. For example, X may be an alkylene group having a structure in which two alkyl groups are bonded, and this alkylene group and M may form a ring.
Specific examples of the transition metal compound (A) include compounds represented by the following formulas.

Copolymerization of ethylene, a cyclic olefin having an alicyclic structure, and a cyclic olefin containing an aromatic structure in the presence of the transition metal compound (A) produces a copolymer having a high molecular weight with relatively high activity. can do This is because at least one of R ⁶ ' to R ⁸ ', particularly R ^{6 '} and R ^{7 '} , is a tertiary hydrocarbon group, the aromatic structure portion of the cyclic olefin having an aromatic structure is catalytically active. The inventors speculate that it may suppress point-approaching and may also suppress electronic influences. It is also possible that the electron-donating property of the tertiary hydrocarbon group supplies electrons to the metal, which is considered to be the active site of the transition metal compound, to increase the reaction activity.

Furthermore, when R ^{6 '} to R ⁸ ' also contain an aryl group or a substituted aryl group, these aryl groups have a cyclic structure, preferably a structure that is easy to rotate, compared to olefins such as ethylene. A bulky cyclic olefin may have the effect of making the active site more accessible. In addition, the aromatic structural site of the aryl group can be expected to have the effect of increasing the local concentration by expressing affinity for the aromatic structural site of the cyclic olefin having the aromatic structure, and the polymerization activity is high. Possibility of being a catalyst is also considered.
The transition metal compound (A-1) of the present invention is represented by the following general formula [A-1].

All of R 1 ' to R ⁸ ', M, X and n above are ^synonymous with R ^{1 '} to R ^{8 '} , M, X and n in general formula [A] representing the transition metal compound (A). However, as described above, when R ^{1 '} to R 5 ' ^combine with each other to form a ring structure, the ring structure is limited to an alicyclic structure.

Compounds such as those described above are novel compounds, and when these compounds are used as catalysts for olefin polymerization, there is a tendency to easily obtain polymers having high activity and high molecular weight as described above.

[Method for producing transition metal compound]
The transition metal compound (A) of the present invention can be produced by a combination of known methods, and an example of a representative synthesis route is shown below, but the production method is not particularly limited.
As a manufacturing method, for example,
A pyrazole compound (a-1) represented by the following general formula [a-1] and an alkyllithium (a-2) are reacted to form an anion body (a-1) of a pyrazole compound represented by the following general formula [a-3]. A step (1-1) for producing a-3), and reacting the anion (a-3) with a compound (a-4) represented by the following general formula [a-4] to obtain Step (1-2) for producing transition metal compound (A) represented by [A]
A manufacturing method comprising:

[In formula [a-1], formula [a-3] and formula [a-4], R ^{1` to R 8` ,} M, X and n are respectively R ^{1`</sup> to R Synonymous with <sup>8`} , M, X and n. ]
First, various cyclopentadiene compounds can be produced by known methods, and the production method is not particularly limited. For example, JP-A-2000-136195, JP-A-2009-24019, Japanese Patent No. 3674509, International Publication No. 1998/015510, International Publication No. 2000/049029, "J.Organomet.Chem. 1999, 577, Chem. 2003, 677, 133.”, “Organometallics 1988, 7, 1828.”, “Organometallics 1996, 15, 4857.” Organometallics 2004, 23, 4693.”, “J. Am. Chem. Soc. 2004, 126, 2089.”, “Macromol. Chem. Phys. 2545.", "Chem. Rev. 1992, 92, 965.", "Science 2012, 338, 504."

Methods for deriving compound (a-4) from various cyclopentadiene compounds are known, and the production method is not particularly limited. As known production methods, for example, "Organometallics 2006, 25, 631.", "Macromolecules 2000, 33, 2796.", "J. Organomet. Chem. 1995, 489, 195." , 118, 1906.” and “Organometallics 2006, 25, 3824.”.

The pyrazole compound (a-1) can be produced by a known method, and the production method is not particularly limited. Examples of known production methods include "J. Org. Chem. 1985, 50, 4736.", "Inorg. Chem. 2012, 51, 150." be done.

The anion form (a-3) of the pyrazole compound can be produced by a known method, and the production method is not particularly limited. Synth. Catal. 2005, 347, 463.”, “Organometallics, 1997, 16, 2709.”, “Organometallics, 2000, 19.” , 2707.” and “Inorg. Chem. 2009, 48, 5011.”.

The transition metal compound (A) of the present invention can be produced by a known method using the compound (a-4) represented by the general formula [a-4] and the anion form (a-3) of the pyrazole compound. . However, at this time, the anion form (a-3) of the pyrazole compound and the compound (a-4) are selected in a specific combination so as to correspond to the desired structure of the transition metal compound (A). In order to react the two, known production methods can be referred to. Examples of such production methods include the method for producing an anion form of the pyrazole compound, as well as "Macromolecules, 2011, 44, 1986." and the manufacturing method described in.

[Catalyst for olefin polymerization]
The olefin polymerization catalyst of the present invention is
(A) the transition metal compound according to the present invention described above;
(B) (B-1) an organometallic compound,
(B-2) an organoaluminum oxy compound, and (B-3) at least one compound selected from the group consisting of compounds that form an ion pair by reacting with the transition metal compound (A). there is

If necessary, the olefin polymerization catalyst of the present invention may further contain (C) a carrier and further contain (D) an organic compound.

<Compound (B)>
《Organometallic compounds (B-1》
The organometallic compound (B-1) (hereinafter also referred to as "component (B-1)") includes, for example, an organoaluminum compound (B-1a) represented by general formula (B-1a), general formula ( Complex alkylation product (B-1b) of Group 1 metal and aluminum represented by B-1b), dialkyl compound of Group 2 or Group 12 metal represented by general formula (B-1c) (B- Organometallic compounds of groups 1, 2 and 12, 13, such as 1c).

(B-1a): R am Al ₍ OR ^{b )} _n H _p X _q
In formula (B-1a), R ^a and R ^b are each independently a hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms, X is a halogen atom, m is 0<m≦3, n is 0≤n<3, p is 0≤p<3, q is a number satisfying 0≤q<3, and m+n+p+q=3. Examples of the organoaluminum compound (B-1a) include trialkylaluminums such as trimethylaluminum, triethylaluminum and triisobutylaluminum, dialkylaluminum hydrides such as diisobutylaluminum hydride, and tricycloalkylaluminums.

(B-1b): M ² AlR ^a ₄
In formula (B-1b), M ² is Li, Na or K, and R ^a is a hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms. Complex alkylated products (B-1b) include, for example, LiAl(C ₂ H ₅ ) ₄ and LiAl(C ₇ H ₁₅ ) ₄ .

(B-1c): R ^a R ^b M ³
In formula (B-1c), R ^a and R ^b are each independently a hydrocarbon group having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms, and M ³ is Mg, Zn or Cd. Examples of the compound (B-1c) include dimethylmagnesium, diethylmagnesium, di-n-butylmagnesium, ethyl n-butylmagnesium, diphenylmagnesium, dimethylzinc, diethylzinc, di-n-butylzinc and diphenylzinc.

Among the organometallic compounds (B-1), the organoaluminum compound (B-1a) is preferred.
The organometallic compound (B-1) may be used singly or in combination of two or more.

<<Organoaluminum oxy compound (B-2)>>
As the organoaluminumoxy compound (B-2) (hereinafter also referred to as "component (B-2)"), conventionally known aluminoxanes can be used as they are. Specifically, the following general formula [B2-1]

および／または下記一般式［B2-2］

and/or the following general formula [B2-2]

（式中、Ｒは炭素数１から１０の炭化水素基、ｎは2以上の整数を示す。）で表わされる化合物、特開平2-78687号公報、特開平2-167305号公報に記載れたベンゼン不溶性の有機アルミニウムオキシ化合物、特開平3-103407号公報に記載されている二種類以上のアルキル基を有するアルミノキサンが挙げられる。

(Wherein, R is a hydrocarbon group having 1 to 10 carbon atoms, n is an integer of 2 or more.) Compounds described in JP-A-2-78687 and JP-A-2-167305 Benzene-insoluble organoaluminum oxy compounds and aluminoxanes having two or more types of alkyl groups described in JP-A-3-103407 can be mentioned.

Examples of the organoaluminumoxy compound (B-2) include modified methylaluminoxane represented by the following general formula [B2-3].

（式中、Ｒは炭素数１から１０の炭化水素基、ｍおよびｎはそれぞれ独立に２以上の整数を示す。）

(Wherein, R is a hydrocarbon group having 1 to 10 carbon atoms, and m and n each independently represent an integer of 2 or more.)

The modified methylaluminoxanes are prepared using trimethylaluminum and alkylaluminums other than trimethylaluminum. Such compounds are commonly referred to as MMAO. Such MMAOs can be prepared by methods set forth in US Pat. No. 4,960,878 and US Pat. No. 5,041,584.

Furthermore, the organoaluminumoxy compound (B-2) may also include an organoaluminumoxy compound containing boron represented by the following general formula [B2-4].

（式中、Ｒ^cは炭素数１から１０の炭化水素基を示す。Ｒ^dは、互いに同一でも異なっていてもよく、水素原子、ハロゲン原子または炭素数１から１０の炭化水素基を示す。）

(In the formula, R ^c represents a hydrocarbon group having 1 to 10 carbon atoms. R ^d , which may be the same or different, represents a hydrogen atom, a halogen atom or a hydrocarbon group having 1 to 10 carbon atoms. )

As the organoaluminumoxy compound (B-2), methylaluminoxane, which is commercially available and readily available, and MMAO prepared using trimethylaluminum and triisobutylaluminum are preferable. Among these, MMAO with improved solubility in various solvents and improved storage stability is particularly preferred.

<<Compound (B-3) that forms an ion pair by reacting with transition metal complex (A)>>
As the compound (B-3) (hereinafter also referred to as “ionic compound (B-3)” or “component (B-3)”) that reacts with the transition metal complex (A) to form an ion pair, Table No. 1-501950, National Publication No. 1-502036, JP-A-3-179005, JP-A-3-179006, JP-A-3-207703, JP-A-3-207704, USP5321106 Examples thereof include Lewis acids, ionic compounds, borane compounds and carborane compounds described in No. In addition, heteropolycompounds and isopolycompounds may also be mentioned. However, the aforementioned (B-2) organoaluminumoxy compound is not included.

The ionic compound (B-3) preferably includes a boron compound represented by the following general formula [B3-1].

In the formula, R ^e+ includes H ⁺ , carbenium cation, oxonium cation, ammonium cation, phosphonium cation, cycloheptyltrienyl cation, ferrocenium cation having a transition metal, and the like. R ^f to R ⁱ may be the same or different, and are substituents selected from hydrocarbon groups having 1 to 20 carbon atoms, silicon-containing groups, nitrogen-containing groups, oxygen-containing groups, halogen atoms and halogen-containing groups. , preferably a substituted aryl group.

Examples of the boron compound represented by the general formula [B3-1] include those described in [0133] to [0144] of WO 2015/122414.
The ionic compound (B-3) may be used alone or in combination of two or more.

(Carrier (C))
The carrier (C) is an inorganic or organic compound, is a granular or fine particle solid, and is conventionally used in olefin polymerization using a transition metal complex and a carrier as catalyst components. Those described in [0110] to [0122] of 2011-122146 can be used.

(Organic compound component (D))
As a component of the olefin polymerization catalyst, an organic compound component (D) may be used as necessary. The organic compound component (D) is used for the purpose of improving the polymerization performance and physical properties of the produced polymer. Examples of the organic compound component (D) include alcohols, phenolic compounds, carboxylic acids, phosphorus compounds, amides, polyethers and sulfonates.

[Method for producing olefin copolymer]
In the method for producing an olefin copolymer of the present invention, ethylene, an alicyclic cyclic olefin, and a cyclic olefin containing an aromatic structure (collectively referred to simply as " (also referred to as "olefin") is characterized by copolymerization.

In polymerization, the method of using each component constituting the catalyst for olefin polymerization of the present invention and the order of addition to the polymerization vessel are arbitrarily selected, but the following methods are exemplified. Hereinafter, the transition metal complex (A), compound (B), carrier (C) and organic compound component (D) are also referred to as "components (A) to (D)" respectively.
(1) A method of adding component (A) alone to a polymerization vessel.
(2) A method of adding components (A) and (B) to a polymerization vessel in any order.
(3) A method in which the catalyst component in which the component (A) is supported on the component (C) and the component (B) are added in any order to the polymerization reactor.
(4) A method of adding a catalyst component in which component (B) is supported on component (C) and component (A) in an arbitrary order to a polymerization vessel.
(5) A method of adding a catalyst component in which component (A) and component (B) are supported on component (C) to a polymerization vessel.

In each of the above methods, component (D) may be added at any stage.
In each of the above methods, at least two of each catalyst component may be pre-contacted.

In the above methods (4) and (5) in which component (B) is supported, component (B) that is not supported may be added in any order, if desired. In this case, the components (B) may be the same or different. Further, the solid catalyst component in which the component (A) is supported on the component (C), and the solid catalyst component in which the component (A) and the component (B) are supported on the component (C), even if the olefin is prepolymerized A further catalyst component may be supported on the prepolymerized solid catalyst component.

Olefin polymerization can be carried out by either a liquid phase polymerization method such as solution polymerization or suspension polymerization, or a gas phase polymerization method. Examples of inert hydrocarbon media used in the liquid phase polymerization method include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene; cyclopentane, cyclohexane, methylcyclopentane, and the like. aromatic hydrocarbons such as benzene, toluene and xylene; and halogenated hydrocarbons such as ethylene chloride, chlorobenzene and dichloromethane. The inert hydrocarbon medium may be used singly or in combination of two or more.

When olefin polymerization is carried out using the olefin polymerization catalyst as described above, the transition metal compound (A) is generally 10 ^-12 to 10 ^-2 mol, preferably 10 ^-10 to 10 mol per liter of reaction volume. It is used in such an amount that it becomes ^-3 mol.

The organometallic compound (B-1) has a molar ratio [(B-1)/M] between the organometallic compound (B-1) and all the transition metal atoms (M) in the transition metal compound (A). It is used in an amount of 0.01 to 50,000, preferably 0.05 to 10,000.

The organoaluminumoxy compound (B-2) has a molar ratio of the aluminum atoms in the organoaluminumoxy compound (B-2) to the total transition metal (M) in the transition metal compound (A) [(B-2) /M] is usually 10 to 5,000, preferably 20 to 2,000.

The ionized ionic compound (B-3) has a molar ratio [(B-3)/M] between the ionized ionic compound (B-3) and the transition metal atom (M) in the transition metal compound (A). , usually from 1 to 10,000, preferably from 1 to 5,000.

When the carrier (C) is used, the weight ratio [(A)/(C)] of the transition metal compound (A) and the carrier (C) is preferably 0.0001 to 1, more preferably 0.0005 to 0. .5, more preferably 0.001 to 0.1.

In the production method of the present invention, the polymerization temperature in the polymerization step is usually −50 to +200° C., preferably 0 to 180° C.; the polymerization pressure is usually normal pressure to 10 MPa gauge pressure, preferably normal pressure to 5 MPa gauge. pressure. The polymerization reaction can be carried out in any of a batch system, a semi-continuous system and a continuous system. Furthermore, the polymerization can be carried out in two or more stages with different reaction conditions.

The molecular weight of the resulting olefin polymer can be adjusted by allowing hydrogen to exist in the polymerization system, by changing the polymerization temperature, or by adjusting the amount of compound (B) used. When hydrogen is added, the appropriate amount thereof is about 0.001 to 5,000 NL per 1 kg of the olefin polymer produced.

The olefin to be subjected to the polymerization reaction in the method for producing an olefin polymer of the present invention is ethylene, and a linear or branched α-olefin having 3 or more carbon atoms can also be used in combination. Moreover, the following cyclic olefins are also essential components. That is, they are an alicyclic cyclic olefin (Z-2) and a cyclic olefin (Z-3) containing an aromatic structure.

(Z-1) Ethylene and any linear or branched α-olefin having 3 or more carbon atoms In the method for producing an olefin polymer of the present invention, ethylene is subjected to a polymerization reaction.
Optionally, linear or branched α-olefins having 3 or more carbon atoms may also be subjected to the polymerization reaction. The α-olefin preferably has 3 to 30 carbon atoms, more preferably 2 to 30 carbon atoms.

Specific examples of α-olefins include propylene, 1-butene, 2-butene, 1-pentene, 3-methyl-1-butene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

Hereinafter, ethylene and any linear or branched α-olefin having 3 or more carbon atoms will also be collectively referred to as “α-olefin (Z-1)”.

(Z-2) Alicyclic cyclic olefin (Z-2) (hereinafter also simply referred to as “cyclic olefin (Z-2)”) is represented by the following general formula [Z-2] Compounds of the formula are preferred. By using such a compound, there is a tendency to easily obtain a polymer having a high refractive index.

（上記式［Ｚ－２］中、ｎは０または１であり、ｍは０または正の整数であり、ｑは０または１であり、Ｒ¹～Ｒ¹⁸ならびにＲ^aおよびＲ^bは、それぞれ独立に、水素原子、ハロゲン原子またはハロゲン原子で置換されていてもよい炭化水素基であり、Ｒ¹⁵～Ｒ¹⁸は互いに結合して単環または多環を形成していてもよく、かつ、該単環または多環は二重結合を有していてもよく、またＲ¹⁵とＲ¹⁶とで、またはＲ¹⁷とＲ¹⁸とでアルキリデン基を形成していてもよい。ただし、該単環および多環は芳香環を含まない。）

(In the above formula [Z-2], n is 0 or 1, m is 0 or a positive integer, q is 0 or 1, R ¹ to R ¹⁸ and R ^a and R ^b are each independently a hydrogen ^atom , a halogen ^atom , or a hydrocarbon group optionally substituted with a halogen atom; The monocyclic or polycyclic ring may have a double bond, and R ¹⁵ and R ¹⁶ or R ¹⁷ and R ¹⁸ may form an alkylidene group, provided that the monocyclic and A polycycle does not contain an aromatic ring.)

Among these, the olefin copolymer produced by the production method of the present invention contains structural units derived from bicyclo[2.2.1]-2-heptene, tetracyclo[6.2.1.1 ^3,6 . 0 ^2,7 ]dodeca-4-ene (tetracyclo[4.4.0.1 ^2,5 .1 ^7,10 ]-3-dodecene)-derived structural unit and hexacyclo[6,6,1,1 ^{3, 6,1 10,13} ,0 ^2,7 ,0 ^9,14 ]heptadeca-4-ene-derived structural units and the like, and bicyclo[2.2.1] -2-heptene-derived structural units and tetracyclo[6.2.1.1 ^3,6 . 0 ^2,7 ] ^dodeca -4-ene-derived structural units. 0 ^2,7 ]dodeca-4-ene-derived structural units are particularly preferred.

(Z-3) Aromatic structure-containing cyclic olefin (Z-3) (hereinafter also simply referred to as "cyclic olefin (Z-3)") containing an aromatic structure includes, for example, the following formula (Z- 31), a compound represented by the following formula (Z-32), a compound represented by the following formula (Z-33), and the like. These cyclic olefins having an aromatic structure may be used singly or in combination of two or more.

In the above formula (Z-31), n and q are each independently 0, 1 or 2. n is preferably 0 or 1, more preferably 0. q is preferably 0 or 1, more preferably 0.

R ¹ to R ¹⁷ are each independently a hydrogen atom, a halogen atom other than a fluorine atom, or a hydrocarbon group having ¹ to 20 carbon atoms optionally substituted with a halogen atom other than a fluorine atom; It is preferred that one of R ¹⁷ is a bond and R ¹⁵ is a bond.

Each of R ¹ to R ¹⁷ is preferably a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom.
When q=0, R ¹⁰ and R ¹¹ , R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁴ and R ¹⁵ , R ¹⁵ and R ¹⁰ are each independently bonded to each other. may form a monocyclic or polycyclic ring, and when q = 1 or 2, R ¹⁰ and R ¹¹ , R ¹¹ and R ¹⁷ , R ¹⁷ and R ¹⁷ , R ¹⁷ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ¹⁴ and R ¹⁵ , R ¹⁵ and R ¹⁶ , R ¹⁶ and R ¹⁶ , R ¹⁶ and R ¹⁰ are each independently bonded to each other to form a monocyclic or polycyclic ring. Also, the monocyclic ring or the polycyclic ring may have a double bond, and the monocyclic ring or the polycyclic ring may be an aromatic ring.

Among the above formula (Z-31), compounds represented by formula (Z-31′) described later are preferred.

In formula (Z-32) above, n and m are each independently 0, 1 or 2, and q is 1, 2 or 3. m is preferably 0 or 1, more preferably 1. n is preferably 0 or 1, more preferably 0. q is preferably 1 or 2, more preferably 1.

Each of R ¹⁸ to R ³¹ is independently a hydrogen atom, a halogen atom other than a fluorine atom, or a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a halogen atom other than a fluorine atom.

Each of R ¹⁸ to R ³¹ is preferably a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom.
When q=1, R ²⁸ and R ²⁹ , R ²⁹ and R ³⁰ , and R ³⁰ and R ³¹ may be independently bonded to each other to form a monocyclic or polycyclic ring, or q=2 or when 3, R ²⁸ and R ²⁸ , R ²⁸ and R ²⁹ , R ²⁹ and R ³⁰ , R ³⁰ and R ³¹ , R ³¹ and R ³¹ are each independently bonded to each other to form a monocyclic or polycyclic ring; The monocyclic ring or the polycyclic ring may have a double bond, and the monocyclic ring or the polycyclic ring may be an aromatic ring.

In the above formula (Z-33), q is 1, 2 or 3, preferably 1 or 2, more preferably 1.
Each of R ³² to R ³⁹ is independently a hydrogen atom, a halogen atom other than a fluorine atom, or a hydrocarbon group having 1 to 20 carbon atoms which may be substituted with a halogen atom other than a fluorine atom.

Each of R ³² to R ³⁹ is preferably a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, more preferably a hydrogen atom.
When q=1, R ³⁶ and R ³⁷ , R ³⁷ and R ³⁸ , and R ³⁸ and R ³⁹ may be independently bonded to each other to form a monocyclic or polycyclic ring, and q=2 or when 3, R ³⁶ and R ³⁶ , R ³⁶ and R ³⁷ , R ³⁷ and R ³⁸ , R ³⁸ and R ³⁹ , R ³⁹ and R ³⁹ are each independently bonded to each other to form a monocyclic or polycyclic ring; The monocyclic ring or the polycyclic ring may have a double bond, and the monocyclic ring or the polycyclic ring may be an aromatic ring.

The hydrocarbon groups having 1 to 20 carbon atoms each independently include, for example, alkyl groups having 1 to 20 carbon atoms, cycloalkyl groups having 3 to 15 carbon atoms, and aromatic hydrocarbon groups. be done. More specifically, alkyl groups include methyl group, ethyl group, propyl group, isopropyl group, amyl group, hexyl group, octyl group, decyl group, dodecyl group and octadecyl group, and cycloalkyl groups include cyclohexyl Examples of the aromatic hydrocarbon group include aryl groups such as phenyl group, tolyl group, naphthyl group, benzyl group and phenylethyl group, and aralkyl groups. These hydrocarbon groups may be substituted with halogen atoms other than fluorine atoms.

Among these, the cyclic olefin (Z-3) having an aromatic structure preferably has one aromatic ring, for example, at least one selected from benzonorbornadiene, indenenorbornene and methylphenylnorbornene. preferable.

Further, the cyclic olefin (Z-3) having an aromatic structure includes, for example, a compound represented by the following formula (Z-31′), a compound represented by the following formula (Z-32′), a compound represented by the following formula (Z- 33'), and the like. These cyclic olefins (Z-3) having an aromatic structure may be used singly or in combination of two or more.

In the above formulas (Z-31′), (Z-32′) and (Z-33′), m and n are 0, 1 or 2, R ¹ to R ³⁶ are each independently a hydrogen atom , a halogen atom excluding a fluorine atom, or a hydrocarbon group having 1 to 20 carbon atoms optionally substituted with a halogen atom excluding a fluorine atom, wherein R ¹⁰ and R ¹¹ , R ¹¹ and R ¹² , R ¹² and R ¹³ , R ¹³ and R ¹⁴ , R ²⁵ and R ²⁶ , R ²⁶ and R ²⁷ , R ²⁷ and R ²⁸ , R ³³ and R ³⁴ , R ³⁴ and R ³⁵ , R ³⁵ and R ³⁶ are each independently They may combine with each other to form a single ring, and the single ring may have a double bond.

In the above formulas (Z-31'), (Z-32') and (Z-33'), m is preferably 0 or 1, more preferably 1. n is preferably 0 or 1, more preferably 0. R ¹ to R ³⁶ are preferably hydrogen atoms or hydrocarbon groups having 1 to 20 carbon atoms, more preferably hydrogen atoms.

The hydrocarbon groups having 1 to 20 carbon atoms each independently include, for example, alkyl groups having 1 to 20 carbon atoms, cycloalkyl groups having 3 to 15 carbon atoms, and aromatic hydrocarbon groups. be done. More specifically, alkyl groups include methyl group, ethyl group, propyl group, isopropyl group, amyl group, hexyl group, octyl group, decyl group, dodecyl group and octadecyl group, and cycloalkyl groups include cyclohexyl Examples of the aromatic hydrocarbon group include aryl groups such as phenyl group, tolyl group, naphthyl group, benzyl group and phenylethyl group, and aralkyl groups. These hydrocarbon groups may be substituted with halogen atoms other than fluorine atoms.

Among these, the cyclic olefin (Z-3) having an aromatic structure preferably has one aromatic ring, for example, at least one selected from benzonorbornadiene, indenenorbornene and methylphenylnorbornene. preferable.

The cyclic olefin (Z-3) having an aromatic structure as described above can adjust the Abbe number of the olefin copolymer obtained by the method of the present invention. It is suitable for controlling physical properties when obtaining an olefin copolymer having physical properties.

Further examples of olefins subjected to the polymerization reaction in the method for producing an olefin polymer of the present invention include conjugated/nonconjugated polyenes and vinylcyclohexane.
The conjugated/nonconjugated polyenes include cyclic or chain hydrocarbons having 4 to 30, preferably 4 to 20 carbon atoms and two or more double bonds. Specific examples include butadiene, isoprene, 4-methyl-1,3-pentadiene, 1,3-pentadiene, 1,4-pentadiene, 1,5-hexadiene, 1,4-hexadiene, 1,3-hexadiene, 1,3-octadiene, 1,4-octadiene, 1,5-octadiene, 1,6-octadiene, 1,7-octadiene, ethylidenenorbornene, vinylnorbornene, dicyclopentadiene, 7-methyl-1,6-octadiene, 4-ethylidene-8-methyl-1,7-nonadiene, 5,9-dimethyl-1,4,8-decatriene butadiene, isoprene, ethylidenenorbornene, vinylnorbornene, dicyclopentadiene, etc. JP-A-2011-122146 and the compounds exemplified in [0211] of

In the method for producing an olefin polymer of the present invention, a polymerizable compound other than an olefin may be polymerized together with the olefin described above. Examples of such polymerizable compounds include a polar group and a polymerizable unsaturated bond. aromatic vinyl compounds, and functional group-containing styrene derivatives.

Specific examples of the compound having a polar group and a polymerizable unsaturated bond include compounds exemplified as unsaturated hydrocarbons having a polar group in [0208] to [0211] of JP-A-2011-122146.

Specific examples of aromatic vinyl compounds and functional group-containing styrene derivatives include compounds exemplified in [0211] of JP-A-2011-122146.
In a preferred embodiment of the production method of the present invention, ethylene and tetracyclo[6.2.1.1 ^3,6 . 0 ^2,7 ]dodeca-4-ene with benzonorbornadiene, indenenorbornene and methylphenylnorbornene (preferably benzonorbornadiene) as the cyclic olefin (Z-3).

In the production method of the present invention, the pressure of the α-olefin (Z-1) and the concentrations of the cyclic olefins (Z-2) and (Z-3) can be arbitrarily set and are not particularly limited. . The pressure of the α-olefin (Z-1) is preferably the polymerization pressure described above.

Cyclic olefin (Z-2) is, for example, preferably 0.0001 to 100 mol/liter, more preferably 0.001 to 10 mol/liter in the case of liquid phase polymerization using the inert solvent, and further It is preferably used under conditions of 0.01 to 1 mol/liter. Further, the concentration of the cyclic olefin (Z-3) is preferably 0.0001 to 1000 mol/liter, more preferably 0.001 to 100 mol/liter, still more preferably 0.01 to 10 mol/liter. Used in conditions.

Although the (Z-2)/(Z-3) molar ratio to be used can be set arbitrarily, it is preferably 0.01-10. A more preferred lower limit is 0.02, more preferably 0.05, and particularly preferably 0.1. On the other hand, the upper limit is more preferably 5, more preferably 2, and particularly preferably 1.

As described above, the olefin polymer obtained by the method for producing an olefin polymer of the present invention can be made into a resin with adjusted refractive index, Abbe number, etc., and can be used, for example, as a material for lenses. .

EXAMPLES The present invention will be described in more detail based on examples below, but the present invention is not limited to these.

[Measuring method]
[Structure of Transition Metal Compound]
The structure of the transition metal compound was determined by ¹ H-NMR spectrum (270 MHz, JEOL GSH-270).

[Polymer Weight Average Molecular Weight (Mw), Molecular Weight Distribution (Mw/Mn)]
The weight average molecular weight (Mw) and number average molecular weight (Mn) of the olefin polymer were determined by gel permeation chromatography (GPC). It was calculated from the molecular weight distribution curve obtained by Waters "Alliance GPC 2000" gel permeation chromatograph (high temperature size exclusion chromatograph), the operating conditions are as follows:

<Apparatus used and conditions>
Measuring device; gel permeation chromatograph alliance GPC2000 type (Waters)
Analysis software; chromatography data system Empower (trademark, Waters)
Column; TSKgel GMH6-HT × 2 + TSKgel GMH6-HT × 2
(Inner diameter 7.5 mm x length 30 cm, Tosoh Corporation)
Mobile phase; o-dichlorobenzene [= ODCB] (Fujifilm Wako Pure Chemical Co., Ltd. special grade reagent)
Detector: Differential refractometer (built-in)
Column temperature; 140°C
Flow rate; 1.0 mL/min
Injection volume: 400 μL
Sampling time interval; 1 second Sample concentration; 0.15% (w/v)
Molecular weight calibration Monodisperse polystyrene (Tosoh Corporation) / Molecular weight from 495 to 20.6 million

[Polymer comonomer (cyclic olefin) content]
The comonomer (cyclic olefin) content of the polymer was determined by ¹³ C-NMR spectrum according to [0216] to [0219] of JP-A-2011-122146.

[Tg of polymer]
DSC measurement was performed under the following conditions to determine the glass transition temperature (Tg) of the polymer.
Apparatus; DSC6220 from SII Nano Technology Co., Ltd.
Measurement conditions: A sample held at 300°C for 5 minutes was rapidly cooled to 0°C and then heated to 250°C at a heating rate of 20°C/min to determine Tg.

[Production of titanium compound]
[Synthesis Example 1]
A 50 mL reactor was charged with 1.84 g (10.0 mmol) of dipivaloylmethane and 10 mL of methanol, 0.75 g (15 mmol) of hydrazine monohydrate and 0.1 mL of hydrochloric acid were added while stirring, and the mixture was heated under reflux for 2 hours. did. Water was added, the soluble matter was extracted with n-hexane, the resulting fraction was washed with water and saturated brine, and dried over anhydrous magnesium sulfate. After filtering the magnesium sulfate, the filtrate was concentrated to obtain 1.73 g of 3,5-di-tert-butyl-1H-pyrazole as a colorless solid (yield 96%).
¹ H-NMR (270 MHz, CDCl ₃ ) δ 9.91 (1H, br s, NH), 5.90 (1H, s, CH), 1.32 (18H, s, C(CH ₃ ) ₃ ) ppm

[Example A1]
186 mg (1.03 mmol) of 3,5-di-tert-butyl-1H-pyrazole obtained in Synthesis Example 1 and 10 mL of n-hexane were charged into a 30 mL reactor which was sufficiently dried and purged with nitrogen, and stirred. After adding 0.67 mL of n-butyllithium solution (n-hexane solution, 1.64 M, 1.1 mmol) to this solution at 0° C., the mixture was stirred at room temperature for 3 hours, and the reaction solution was concentrated to dryness.

288 mg (1.05 mmol) of tert-butylcyclopentadienyltrichlorotitanium and 5 mL of diethyl ether were charged into another 30 mL reactor which was sufficiently dried and purged with nitrogen, and stirred. To this solution, a solution prepared from the previously obtained dried product and 5 mL of diethyl ether was added at -78°C, and stirring was continued at room temperature for 24 hours. After distilling off the solvent of the reaction solution, dichloromethane was added to the resulting orange-yellow solid to prepare a suspension, and insoluble matter was removed by celite filtration. After concentrating the obtained solution under reduced pressure, n-hexane was added, and the orange crystals obtained by standing at −30° C. were collected, washed, and dried under reduced pressure to give the crystals represented by the following formula (1). 270 mg (yield 63%) of titanium compound (1) was obtained.
¹ H-NMR (270 MHz, CDCl ₃ ) δ 6.77 (2H, t, J = 2.6 Hz, CpH), 6.58 (1H, s, CH), 6.06 (2H, t, J = 2 .6 Hz, CpH), 1.46 (9H, s, C( _CH3 ) ₃ ), 1.35 (18H, s, C( _CH3 ) ₃ ) ppm

〔式中、ｔＢｕはｔｅｒｔ－ブチル基である。〕

[In the formula, tBu is a tert-butyl group. ]

[Example A2]
189 mg (1.05 mmol) of 3,5-di-tert-butyl-1H-pyrazole obtained in Synthesis Example 1 and 10 mL of n-hexane were charged into a 30 mL reactor which was sufficiently dried and purged with nitrogen, and stirred. After adding 0.69 mL of n-butyllithium solution (n-hexane solution, 1.59 M, 1.1 mmol) to this solution at 0° C., the mixture was stirred at room temperature for 3 hours, and the reaction solution was concentrated to dryness.

276 mg (1.02 mmol) of (indenyl)titanium trichloride and 5 mL of diethyl ether were charged into another 30 mL reactor which was sufficiently dried and purged with nitrogen, and stirred. To this solution, a solution prepared from the previously obtained dried product and 5 mL of diethyl ether was added at -78°C, and stirring was continued at room temperature for 24 hours. After distilling off the solvent of the reaction solution, dichloromethane was added to the resulting purple-brown solid to prepare a suspension, and insoluble matter was removed by celite filtration. After the resulting solution was concentrated under reduced pressure, n-hexane was added, and the mixture was allowed to stand at -30°C to remove the generated solid matter. The filtrate was concentrated, and the resulting dark purple crystals were collected, washed, and dried under reduced pressure to obtain 91 mg (22% yield) of titanium compound (2) represented by the following formula (2).
¹ H-NMR (270 MHz, CDCl ₃ ) δ 7.58-7.61 (2H, m, IndH), 7.29-7.31 (2H, m, IndH), 7.02 (2H, d, J = 3.3 Hz, IndH), 6.73 (1H, t, J = 3.3 Hz, IndH), 6.56 (1H, s, CH), 1.31 (18H, s, C( _CH3 ) ₃ ) ppm

[Production of olefin polymer]
[Example B1]
A dry pressure-resistant autoclave with an inner volume of 2.0 L was sufficiently purged with nitrogen, and 710 mL of a dehydrated and purified cyclohexane/hexane (9/1) mixed solution, tetracyclo[6.2.1.1 ^3,6 . 0 ^2,7 ]dodeca-4-ene (hereinafter referred to as “tetracyclododecene or “TD”) 50 mmol, benzonorbornadiene (hereinafter referred to as “BNBD”) 240 mmol, and triethylaluminum in terms of 1 aluminum atom. .0 mmol was sequentially inserted under a stream of nitrogen. Then, the temperature was raised to 50° C., and ethylene was supplied so that the ethylene partial pressure became 0.1 MPaG, and this state was maintained. Thereafter, 0.002 mmol of the titanium compound (1) obtained in Example A1 was added, followed by 0.008 mmol of triphenylcarbenium tetrakis(pentafluorophenyl)borate to initiate polymerization. While maintaining the inner temperature of 50° C., ethylene was supplied so that the ethylene partial pressure was maintained at 0.1 MPaG, and polymerization was carried out for 5 minutes. After a predetermined time had passed, the supply of ethylene was stopped and the polymerization was stopped by adding a small amount of methanol. The reactant was added to 3 liters of acetone/methanol (3/1) mixed solvent containing a small amount of hydrochloric acid to precipitate the polymer. After washing with the same solvent, it was dried under reduced pressure at 130° C. for 10 hours to obtain 7.86 g of an ethylene/tetracyclododecene/benzonorbornadiene copolymer. Polymerization activity and physical properties of the ethylene/tetracyclododecene/benzonorbornadiene copolymer are as follows.
Polymerization activity: 3.93 kg-polymer/mmol-Ti
Glass transition temperature: 124°C
Intrinsic viscosity [η]: 6.5dl/g
Structural unit molar ratio (ethylene: TD: BNBD) = 65.5: 16.0: 18.4

[Example B2]
The same operation as in Example B1 was performed except that the titanium compound (1) was changed to the titanium compound (2) obtained in Example A2, and 0.91 g of an ethylene/tetracyclododecene/benzonorbornadiene copolymer was added. Obtained. Polymerization activity and physical properties of the ethylene/tetracyclododecene/benzonorbornadiene copolymer are as follows.
Polymerization activity: 0.45 kg-polymer/mmol-Ti
Glass transition temperature: 96°C
Intrinsic viscosity [η]: 4.45dl/g
Structural unit molar ratio (ethylene: TD: BNBD) = 72.3: 14.6: 13.1

[Comparative Example B1]
Titanium compound (1) was synthesized by the method described in Macromolcules 2011, 44, 1986-1998, 0.005 mmol of titanium compound (3) represented by the following formula (3), 1.91 g of an ethylene/tetracyclododecene/benzonorbornadiene copolymer was obtained in the same manner as in Example B1 except that the amount of triphenylcarbenium tetrakis(pentafluorophenyl)borate was changed to 0.02 mmol. The physical properties and the like of the ethylene/tetracyclododecene/benzonorbornadiene copolymer are shown below.

〔式中、ｔＢｕはｔｅｒｔ－ブチル基であり、ｉＰｒはイソプロピル基である。〕

[In the formula, tBu is a tert-butyl group and iPr is an isopropyl group. ]

Polymerization activity: 0.38 kg-polymer/mmol-Ti
Glass transition temperature: 163°C
Intrinsic viscosity [η]: 2.44dl/g
Structural unit molar ratio (ethylene: TD: BNBD) = 61.7: 20.9: 17.3

[Production of titanium compound]
[Synthesis Example 2]
12.8 g (114 mmol) of potassium tert-butoxide and 20 mL of dehydrated DMF were added to 100 mL Schlenk that had been thoroughly dried by heating, and then 10.0 g (100 mmol) of pinacoline and 19.2 g of methyl 4-tert-butylbenzoate were added while cooling to 0°C. (100 mmol) was added and stirred overnight while the temperature was slowly raised to room temperature. Diluted hydrochloric acid and water were added under cooling at 0°C, and the mixture was extracted with ethyl acetate. The resulting fraction was washed with water and saturated brine and dried over anhydrous magnesium sulfate. After filtration and concentration under reduced pressure, 30 mL of methanol, 5.5 mL (113 mmol) of hydrazine monohydrate and 0.1 mL of hydrochloric acid were added to the obtained light brown liquid at room temperature, and the mixture was heated under reflux for 1 hour. After cooling to room temperature, water was added and the mixture was extracted with ethyl acetate. The resulting fraction was washed with water and saturated brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. Hexane was added to the resulting oil, and the precipitated component was collected by filtration to give 3-(tert-butyl)-5-(4-(tert-butyl)phenyl)-1H-pyrazole as a colorless solid. 14.4 g (yield 56%) was obtained.
¹ H-NMR (270 MHz, CDCl ₃ ) δ 10.46 (1H, br s, NH), 7.67 (2H, br s, ArH), 7.42 (2H, d, J = 8.6 Hz, ArH ), 6.36 (1H, s, CH), 1.38 (9H, s, C( _CH3 ) ₃ ), 1.34 (9H, s, C( _CH3 ) ₃ ) ppm

[Example A3]
257 mg (1.0 mmol) of 3-(tert-butyl)-5-(4-(tert-butyl)phenyl)-1H-pyrazole and 20 mL of diethyl ether were charged into a 50 mL reactor which was sufficiently dried and purged with nitrogen, and stirred. . To this solution, 0.70 mL of n-butyllithium solution (n-hexane solution, 1.58 M, 1.1 mmol) was added at 0° C., and the mixture was stirred at room temperature for 2 hours. 275 mg (1.0 mmol) of tert-butylcyclopentadienyltrichlorotitanium and 20 mL of diethyl ether were charged into a 100-mL reactor that was sufficiently dried and purged with nitrogen, and stirred. was added and stirred at room temperature for 15 hours. After distilling off the solvent of the reaction solution, dichloromethane was added to the resulting solid to prepare a suspension, and insoluble matter was removed by celite filtration. After concentrating the obtained solution under reduced pressure, n-hexane was added, and the orange crystals obtained by standing at −30° C. were collected, washed, and dried under reduced pressure to obtain a compound represented by the following formula (4). 312 mg (yield 63%) of a titanium compound obtained by
¹ H-NMR (495 MHz, CDCl ₃ ) δ 7.76 (2H, d, J = 8.4 Hz, ArH), 7.43 (2H, d, J = 8.4 Hz, ArH), 7.03 (1H , s, CH), 6.75 (2H, t, J = 2.5 Hz, CpH), 6.33 (2H, t, J = 2.5 Hz, CpH), 1.41 (9H, s, (CH ₃ ) ₃ ), 1.35 (9H, s, ( _CH3 ) ₃ ), 1.27 (9H, s, ( _CH3 ) ₃ ) ppm.

〔式中、ｔＢｕはｔｅｒｔ－ブチル基である。〕

[In the formula, tBu is a tert-butyl group. ]

[Synthesis Example 3]
12.7 g (113 mmol) of potassium tert-butoxide and 20 mL of dehydrated DMF were added to 100 mL Schlenk that had been thoroughly dried by heating, and then 15.1 g (100 mmol) of p-methoxyacetophenone and 11.6 g (100 mmol) of methyl pivalate were added under cooling to 0°C. ) was added, and the mixture was stirred overnight while the temperature was slowly raised to room temperature. Diluted hydrochloric acid and water were added under cooling at 0°C, and the mixture was extracted with ethyl acetate. The resulting fraction was washed with water and saturated brine and dried over anhydrous magnesium sulfate. After filtration and concentration under reduced pressure, 30 mL of methanol, 4.5 mL (92 mmol) of hydrazine monohydrate and 0.1 mL of hydrochloric acid were added to the obtained brown solid at room temperature, and the mixture was heated under reflux for 1 hour. After cooling to room temperature, water was added and the mixture was extracted with ethyl acetate. The resulting fraction was washed with water and saturated brine, dried over anhydrous magnesium sulfate, filtered and concentrated under reduced pressure. Hexane was added to the resulting oil, and the precipitated component was collected by filtration to give 7.23 g of 3-(tert-butyl)-5-(4-methoxyphenyl)-1H-pyrazole as a pale yellow solid. (Yield 31%).
¹ H-NMR (270 MHz, CDCl ₃ ) δ 9.95 (1H, br s, NH), 7.66 (2H, br s, ArH), 6.96-6.92 (2H, m, ArH), 6.32 (1H, s, CH), 3.84 (3H, s, _CH3 ) 1.37 (9H, s, C( _CH3 ) ₃ ) ppm

[Example A4]
200 mg (0.87 mmol) of 3-(tert-butyl)-5-(4-methoxyphenyl)-1H-pyrazole and 20 mL of diethyl ether were charged into a 50 mL reactor sufficiently dried and purged with nitrogen, and stirred. To this solution, 0.60 mL of n-butyllithium solution (n-hexane solution, 1.58 M, 0.96 mmol) was added at 0° C. and stirred at room temperature for 2 hours. 240 mg (0.87 mmol) of tert-butylcyclopentadienyltrichlorotitanium and 20 mL of diethyl ether were charged and stirred in a 100 mL reactor that was sufficiently dried and purged with nitrogen. and stirred at room temperature for 15 hours. After distilling off the solvent of the reaction solution, dichloromethane was added to the resulting solid to prepare a suspension, and insoluble matter was removed by celite filtration. The resulting solution was concentrated under reduced pressure, n-hexane was added, and the reddish-orange crystals obtained by allowing to stand at −30° C. were collected, washed, and dried under reduced pressure to give the following formula (5). 387 mg (95% yield) of the indicated titanium compound were obtained.
¹ H-NMR (495 MHz, CDCl ₃ ) δ 7.78 (2H, d, J = 8.9 Hz, ArH), 6.97 (1H, s, CH), 6.94 (2H, d, J = 8 .9 Hz, ArH), 6.72 (2H, t, J = 2.5 Hz, CpH), 6.40 (2H, t, J = 2.5 Hz, CpH), 3.85 (3H, s, CH ₃ ), 1.41 (9H, s, ( _CH3 ) ₃ ), 1.22 (9H, s, ( _CH3 ) ₃ ) ppm.

〔式中、ｔＢｕはｔｅｒｔ－ブチル基である。〕

[In the formula, tBu is a tert-butyl group. ]

[Production of olefin polymer]
[Example B3]
The same operation as in Example B1 was performed except that the titanium compound (1) was changed to the titanium compound (4) obtained in Example A3, and 3.54 g of an ethylene/tetracyclododecene/benzonorbornadiene copolymer was prepared. Obtained. Polymerization activity and physical properties of the ethylene/tetracyclododecene/benzonorbornadiene copolymer are as follows.
Polymerization activity: 1.77 kg-polymer/mmol-Ti
Glass transition temperature: 152°C
Intrinsic viscosity [η]: 4.34dl/g
Structural unit molar ratio (ethylene: TD: BNBD) = 60.3: 21.3: 18.4

[Example B4]
The same operation as in Example B1 was performed except that the titanium compound (1) was changed to the titanium compound (5) obtained in Example A4, and 2.12 g of an ethylene/tetracyclododecene/benzonorbornadiene copolymer was prepared. Obtained. Polymerization activity and physical properties of the ethylene/tetracyclododecene/benzonorbornadiene copolymer are as follows.
Polymerization activity: 1.06 kg-polymer/mmol-Ti
Glass transition temperature: 145°C
Intrinsic viscosity [η]: 4.16dl/g
Structural unit molar ratio (ethylene: TD: BNBD) = 62.4: 19.8: 17.8

From the above examples and comparative examples, it can be seen that the olefin polymerization method of the present invention can efficiently produce a cyclic olefin copolymer containing an aromatic structure with high activity and high molecular weight.

Claims (8)

(A) a transition metal compound represented by the following general formula [A] and (B) (B-1) an organometallic compound,
The presence of an olefin polymerization catalyst containing (B-2) an organoaluminumoxy compound and (B-3) at least one compound selected from the group consisting of compounds that form an ion pair by reacting with the transition metal compound. Below is a method for producing an olefin copolymer by copolymerizing ethylene, an alicyclic cyclic olefin, and a cyclic olefin containing an aromatic structure.

[In formula [A],
M is a titanium atom, a zirconium atom, or a hafnium atom;
n is an integer from 1 to 4,
Each X is independently a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, an aluminum-containing group, or a diene is a divalent derivative group,
R ^{1 '} to R ^{8 '} are each independently a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a nitrogen-containing group, a sulfur-containing group, or a phosphorus is a containing group;
Adjacent groups among R ^{1` to R 5` may} be bonded to each other to form a ring,
At least one of R ⁶ ' to R ⁸ ' is a tertiary hydrocarbon group. ] 2. The method for producing an olefin copolymer according to claim 1, wherein M in the general formula [A] is a titanium atom. 2. The method for producing an olefin copolymer according to claim 1, wherein in the general formula [A], R ^{1`</sup> is a hydrocarbon group having 1 to 20 carbon atoms, and R <sup>2`} to R ^5` are hydrogen atoms. . 2. The olefin copolymer according to claim 1, wherein at least one of R ⁶ ' to R ⁸ ' in the general formula [A] is a substituent selected from an aryl group having 6 to 20 carbon atoms or a substituted aryl group. manufacturing method. A transition metal compound represented by the following general formula [A-1].

[In the formula [A-1],
M is a titanium atom, a zirconium atom, or a hafnium atom;
n is an integer from 1 to 4,
Each X is independently a hydrogen atom, a halogen atom, a hydrocarbon group, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a phosphorus-containing group, a boron-containing group, an aluminum-containing group, or a diene is a divalent derivative group,
R ^{1 '} to R ^{8 '} are each independently a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogen atom, a halogen-containing group, a silicon-containing group, an oxygen-containing group, a nitrogen-containing group, a sulfur-containing group, or a phosphorus is a containing group;
Adjacent groups among R ^{1` to R 5` may} be bonded to each other to form a ring structure,
When adjacent groups among R 1 ^′ to R ⁵ ′ are bonded to each other to form a ring structure, the ring structure is an alicyclic structure,
At least one of R ⁶ ' to R ⁸ ' is a tertiary hydrocarbon group. ] 6. The transition metal compound according to claim 5, wherein in the general formula [A-1], M is a titanium atom. 6. The transition metal compound according to claim 5, wherein in the general formula [A-1], R 1 ' is a ^hydrocarbon group having 1 to 20 carbon atoms, and R ^{2 '} to R ^{5 '} are hydrogen atoms. 6. The transition according to claim 5, wherein at least one of R ⁶ ' to R ⁸ ' in the general formula [A-1] is a substituent selected from an aryl group having 6 to 20 carbon atoms or a substituted aryl group. metal compounds.