CN113061203B - Catalyst and preparation method thereof, and preparation method of styrene monomer isotactic polymer - Google Patents

Abstract

The invention provides a catalyst and a preparation method thereof, and a preparation method of a styrene monomer isotactic polymer. The invention provides the catalyst of formula I which is a rare earth catalyst with large steric hindrance and strong conjugated effect ligand chelation, wherein the larger steric hindrance of the chelating ligand weakens the polarities of the meta-position and para-position of the styrene monomer. The interaction between the polar group and the central metal of the rare earth catalyst reduces the poisoning effect of the polar group on the catalyst, and the strong conjugation of the chelating ligand enhances the Lewis acidity of the central metal of the catalyst, which can improve the catalytic activity of the catalyst. , to achieve isotactic polymerization of styrene-based monomers modified with meta- and para-polar groups.

Description

A kind of catalyst and preparation method thereof, and preparation method of styrene monomer isotactic polymer

technical field

The invention relates to the field of organic synthesis, in particular to a catalyst and a preparation method thereof, and a preparation method of a styrene monomer isotactic polymer.

Background technique

Styrene polymers can be divided into three types: isotactic, syndiotactic and atactic according to their tacticity. To date, there are only a handful of catalytic systems that can catalyze isotactic selectivity of styrene-based monomers. Specifically, there are Ziegler-Natta catalysts, titanium and zirconium catalysts chelated by bisphenol ligands, and bisindene rare earth catalysts, which can enable the isotactic selective polymerization of non-polar styrene monomers. However, these catalytic systems are mainly used for isotactic polymerization of styrene.

Recently, patent document CN105440186A, non-patent document Angew.Chem.Int.Ed.2015,54,5205-5209 and Chem.Eur.J.2019,25,2043-2050 reported that chelation using β-bisimine ligand The rare earth catalyst catalyzes the isotactic selective polymerization of styrene monomers substituted with alkoxy groups at the ortho position, and prepares isotactic polymers of styrene monomers functionalized with ortho alkoxy groups. However, for polar styrene monomers without polar substituent groups at the vicinal position (the polar styrene monomers here are polar groups without bulky protecting groups and alkyl aluminum protection), so far, There is no catalytic system yet to polymerize it into isotactic polymers.

It can be seen that the non-rare earth locene catalysts reported in the existing literature can catalyze the isotactic polymerization of styrene monomers with polar groups in the vicinal position, but the non-rare earth locene catalysts can catalyze the isotactic polymerization of styrene monomers without polar groups in the ortho position. Monomers have little catalytic activity. However, other catalytic systems with isotactic selectivity for styrene polymerization can only catalyze the isotactic polymerization of non-polar styrene monomers or polar styrene protected by bulky groups at present. Isotactic polymerisation of polar styrenic monomers without polar groups in the ortho position but with polar groups in the meta and/or para positions.

SUMMARY OF THE INVENTION

In view of this, the object of the present invention is to provide a catalyst and a preparation method thereof, and a preparation method of an isotactic polymer of styrene-based monomers. The catalyst provided by the invention can catalyze the isotactic selective polymerization of styrene monomers with polar substituent groups at meta and/or para positions, has high catalytic activity, and can efficiently obtain styrene monomers Isotactic polymer.

The present invention provides a kind of catalyst, has the structure shown in formula I:

in:

X is a monoanionic ligand, selected from: C1-C16 alkyl group, C4-C16 silyl group, C2-C16 alkylamine group, C4-C20 alkylsilamine group, C6-C20 arylamine group , substituted or unsubstituted C3-C10 allyl, C7-C20 arylmethylene, borohydride, tetramethylaluminum, hydrogen, chlorine, bromine or iodine;

L is a neutral Lewis base chelating ligand, selected from: tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether, pyridine or substituted pyridine; n represents the number of ligands, which is an integer from 0 to 2;

RE is a rare earth element selected from the group consisting of lanthanides, scandium or yttrium.

preferably,

The C1-C16 alkyl group is selected from: methyl, ethyl, n-propyl, isopropyl, n-butyl or n-octyl;

The C4-C16 silyl group is selected from: -CH ₂ Si(CH ₃ ) ₃ , -CH[Si(CH ₃ ) ₃ ] ₂ , -CH ₂ Si(CH ₃ ) ₂ Ph or -CH ₂ SiMe ₂ C ₆ H ₄ OMe-o;

The C2-C16 alkylamine group is selected from: -NMe ₂ , -NEt ₂ , -N ⁿ Pr ₂ , -N ⁱ Pr ₂ or -N ⁿ Bu ₂ ;

The C4-C20 alkylsilamine group is selected from: -N[SiMe ₃ ] ₂ or -N[SiMe ₂ H] ₂ ;

The C6-C20 arylamine group is selected from: -CH ₂ C ₆ H ₄ NMe ₂ -o, -NHPh, -NHC ₆ H ₄ Me-p, -NHC ₆ H ₄ ⁱ Pr-p or -NHC ₆ H ₄ ( ^iPr ) _2-2,6 ;

The substituted or unsubstituted C3-C10 allyl group is selected from: -CH ₂ CH=CH ₂ , -CH ₂ C(Me)=CH ₂ , -(SiMe ₃ )CHCH=CH(SiMe ₃ );

The C7-C20 arylmethylene group is selected from: p-MeC ₆ H ₄ CH ₂ -, p-EtC ₆ H ₄ CH ₂ -, p- ⁱ PrC ₆ H ₄ CH ₂ -, p- ⁿ PrC ₆ H ₄ CH ₂ -, p- ⁿ BuC ₆ H ₄ CH ₂ - or p- ^t BuC ₆ H ₄ CH ₂ -;

The RE is selected from scandium, yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, bait, ytterbium or lutetium.

Preferably, the X is selected from: trimethylsilylmethylene, bistrimethylsilylmethine, allyl, 2-methylallyl, 1,3-bistrimethylsilylene Propyl, hexamethylsilamido, tetramethylsilamido, methyl, benzyl, 4-methylbenzyl, 2-N,N'-dimethylbenzyl, tetramethylaluminum, boron Hydrogen, hydrogen, chlorine or bromine;

The RE is selected from: yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, bait or ytterbium.

Preferably, the X is selected from: trimethylsilylmethylene, allyl, 2-methylallyl, hexamethylsilamido, tetramethylsilamido, benzyl, 4-methyl benzyl, 2-N,N'-dimethylbenzyl, tetramethylaluminum or hydrogen;

The RE is selected from: yttrium, lanthanum, neodymium, gadolinium, holmium, bait or ytterbium.

Preferably, it is selected from the compounds represented by formula I-1 to formula I-8:

The present invention also provides a preparation method of the catalyst described in the above technical scheme, comprising the following steps:

a) Ligand A reacts with alkyl alkali metal reagent MR ¹ to form alkali metal salt B;

b) mixed reaction of alkali metal salt B with rare earth halide RE(X') ₃ suspension and monoanionic alkali metal reagent MX to form a catalyst represented by formula I;

in:

In the MR ¹ , M is an alkali metal, and R ¹ is an alkyl group, a hydrogen or an amine group;

In the RE(X') ₃ , X' is a halogen element;

The solvent in the rare earth halide RE(X') ₃ suspension is a neutral Lewis base;

In the MX, M is an alkali metal, and X is a monoanionic ligand.

The present invention also provides a preparation method of styrene monomer isotactic polymer, comprising:

Under the action of the isotactic selective polymerization catalyst, the styrene monomer represented by the formula II undergoes a polymerization reaction to form the isotactic polymer represented by the formula III;

in,

R is a substituent group at the meta and/or para position on the benzene ring, m is the number of substituent groups R, 1≤m≤3;

R is selected from: C1-C20 alkoxy, C6-C20 aryloxy, C1-C20 alkylthio, C1-C20 silyl, C1-C40 alkyl, C3-C20 alkylsiloxy group, C2-C20 alkylamine group, hydrogen, chlorine, bromine or iodine;

The isotactic selective polymerization catalyst includes a main catalyst;

The main catalyst is the catalyst described in the above technical solutions.

Preferably, the styrene-based monomer is selected from: styrene, p-methylstyrene, m-methylstyrene, 3,5-dimethylstyrene, 4-alkylstyrene, p-methoxybenzene Ethylene, p-methylthiostyrene, m-methoxystyrene, 3,5-dimethoxystyrene, p-fluorostyrene, m-fluorostyrene, p-alkoxystyrene, 2-vinylnaphthalene, 6-Methoxy-2-vinylnaphthalene, p-benzyloxystyrene, 4-(dimethylsilyl)styrene, 4-(trimethylsilyl)styrene, 4-(butene-1) ) styrene, 4-allylstyrene, 4-phenylacetylenestyrene, 4-butylacetylenestyrene, 4-vinylbenzocyclobutene, 4-(trimethylsilylethynyl)benzene Ethylene, 4-alkylthiostyrene, 4-(silyl)styrene, 4-(N'N-dimethylamino)styrene, 4-(N'N-diethylamino)styrene, and 4 One or more of -(N'N-diphenylamino)styrene;

The isotactic polymerization catalyst also includes a cocatalyst;

The cocatalyst includes organoboron salts and main group metal alkyl compounds;

The temperature of the polymerization reaction is 0～160°C, and the time is 1min～100h;

The molar ratio of the main catalyst, the organic boron salt and the main group metal alkyl compound is 1:(0-1):(0-1000);

The molar ratio of the main catalyst to the styrene-based monomer represented by formula II is 1:(50-100000).

Preferably, the styrene-based monomer is selected from styrene, p-methylstyrene, m-methylstyrene, 3,5-dimethylstyrene, 4-alkylstyrene, p-methoxystyrene , p-methylthiostyrene, m-methoxystyrene, 3,5-dimethoxystyrene, p-fluorostyrene, m-fluorostyrene, p-alkoxystyrene, 2-vinylnaphthalene, 6 -Methoxy-2-vinylnaphthalene, p-benzyloxystyrene, 4-(dimethylsilyl)styrene, 4-(trimethylsilyl)styrene, 4-(butene-1) styrene, 4-allylstyrene, 4-phenylacetylenestyrene, 4-butylacetylenestyrene, 4-vinylbenzocyclobutene, 4-(trimethylsilylethynyl)styrene , one or more of 4-alkylthiostyrene and 4-(silyl)styrene;

The organoboron salt is selected from: [NHEt ₃ ][B(C ₆ F ₅ ) ₄ ], [Ph ₃ C][B(C ₆ F ₅ ) ₄ ], [PhNMe ₂ H][B(C ₆ F ₅ ) ₄ ], B(C ₆ F ₅ ) ₃ , 1,4-(C ₆ F ₅ ) ₂ BC ₆ F ₄ B(C ₆ F ₅ ) ₂ and [Ph ₃ C] ₂ [1,4-( One or more of C ₆ F ₅ ) ₃ BC ₆ F ₄ B(C ₆ F ₅ ) ₃ ];

The main group metal alkyl compound is selected from one or more of alkyl aluminum, alkyl magnesium and alkyl zinc.

Preferably, the alkyl aluminum is selected from trimethylaluminum, triethylaluminum, tri-n-butylaluminum, tri-n-propylaluminum, triisobutylaluminum, triisopropylaluminum, One or more of hexylaluminum, trioctylaluminum, diethylaluminum hydride, diisobutylaluminum hydride, methylaluminoxane, dried aluminoxane and modified aluminoxane;

Described alkyl zinc is diethyl zinc;

Described alkyl magnesium is selected from one or more in diethylmagnesium, di-n-propylmagnesium, diisopropylmagnesium and dibutylmagnesium;

The molar ratio of the main catalyst, the organic boron salt and the main group metal alkyl compound is 1:(0-1):(0-500);

The molar ratio of the main catalyst to the styrene monomer represented by formula II is 1:(100-80000).

The above catalyst provided by the present invention is a rare earth catalyst with large steric hindrance and strong conjugated effect ligand chelation, wherein the large steric hindrance of the chelated ligand weakens the polarities of the meta-position and para-position of the styrene monomer. The interaction between the polar group and the central metal of the rare earth catalyst reduces the poisoning effect of the polar group on the catalyst, and the strong conjugation of the chelating ligand enhances the Lewis acidity of the central metal of the catalyst, which can improve the catalytic activity of the catalyst. , to achieve isotactic polymerization of styrene-based monomers modified with meta- and para-polar groups.

The experimental results show that the catalyst of formula I provided by the present invention can realize the isotactic polymerization of styrene monomers modified by meta- and para polar groups, and specifically can catalyze the isotactic selectivity of the same styrene monomers. Homopolymerization, can also catalyze isotactic selective copolymerization between different types of styrene monomers, and the conversion rate of styrene monomers is over 85%, the isotacticity of the prepared isotactic polymer mm>98%.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative work.

Fig. 1 is the hydrogen nuclear magnetic resonance spectrogram of the catalyst of formula I-1 obtained in Example 1;

Fig. 2 is the carbon nuclear magnetic resonance spectrogram of the polymer obtained in Polymerization Example 6;

Fig. 3 is the carbon nuclear magnetic resonance spectrogram of the polymer obtained in Polymerization Example 7;

Fig. 4 is the carbon nuclear magnetic resonance spectrogram of the polymer obtained in Polymerization Example 8;

Fig. 5 is the carbon nuclear magnetic resonance spectrogram of the polymer obtained in Polymerization Example 9;

6 is a carbon nuclear magnetic resonance spectrum of the polymer obtained in Polymerization Example 10.

Detailed ways

The present invention provides a kind of catalyst, has the structure shown in formula I:

in:

X is a monoanionic ligand, selected from: C1-C16 alkyl group, C4-C16 silyl group, C2-C16 alkylamine group, C4-C20 alkylsilamine group, C6-C20 arylamine group , substituted or unsubstituted C3-C10 allyl, C7-C20 arylmethylene, borohydride, tetramethylaluminum, hydrogen, chlorine, bromine or iodine;

L is a neutral Lewis base chelating ligand, selected from: tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether, pyridine or substituted pyridine; n represents the number of ligands, which is an integer from 0 to 2;

RE is a rare earth element selected from lanthanides, scandium or yttrium.

The above catalyst provided by the present invention is a rare earth catalyst with large steric hindrance and strong conjugated effect ligand chelation, wherein the large steric hindrance of the chelated ligand weakens the polarities of the meta-position and para-position of the styrene monomer. The interaction between the polar group and the central metal of the rare earth catalyst reduces the poisoning effect of the polar group on the catalyst, and the strong conjugation of the chelating ligand enhances the Lewis acidity of the central metal of the catalyst, which can improve the catalytic activity of the catalyst. , to achieve isotactic polymerization of styrene-based monomers modified with meta- and para-polar groups. The catalyst of formula I provided by the present invention can catalyze the isotactic selective homopolymerization of the same styrene monomer, and can also catalyze the isotactic selective copolymerization between different types of styrene monomers. Moreover, the catalyst of formula I provided by the present invention can catalyze the polymerization of styrene monomers alone, and can also jointly catalyze the isotactic selection of styrene monomers under the coordination of other cocatalysts (organoboron salts and main group metal alkyl compounds). Sexual aggregation.

Regarding formula I:

X is a monoanionic ligand, selected from: C1-C16 alkyl group, C4-C16 silyl group, C2-C16 alkylamine group, C4-C20 alkylsilamine group, C6-C20 arylamine group , substituted or unsubstituted C3-C10 allyl, C7-C20 arylmethylene (ie ArCH ₂ -), borohydride, tetramethylaluminum, hydrogen, chlorine, bromine or iodine.

The C1-C16 alkyl group is preferably: methyl, ethyl, n-propyl, isopropyl, n-butyl or n-octyl;

The C4-C16 silyl groups are preferably: -CH ₂ Si(CH ₃ ) ₃ , -CH[Si(CH ₃ ) ₃ ] ₂ , -CH ₂ Si(CH ₃ ) ₂ Ph or -CH ₂ SiMe ₂ C ₆ H ₄ OMe-o;

The C2-C16 alkylamine group is preferably: -NMe ₂ , -NEt ₂ , -N ⁿ Pr ₂ , -N ⁱ Pr ₂ or -N ⁿ Bu ₂ ;

The C4-C20 alkylsilamine group is preferably: -N[SiMe ₃ ] ₂ or -N[SiMe ₂ H] ₂ ;

The C6-C20 arylamine group is preferably: -CH ₂ C ₆ H ₄ NMe ₂ -o, -NHPh, -NHC ₆ H ₄ Me-p, -NHC ₆ H ₄ ⁱ Pr-p or -NHC ₆ H ₄ ( ^iPr ) _2-2,6 ;

The substituted or unsubstituted C3-C10 allyl groups are preferably: -CH ₂ CH=CH ₂ , -CH ₂ C(Me)=CH ₂ , -(SiMe ₃ )CHCH=CH(SiMe ₃ );

The C7-C20 arylmethylene groups are preferably: PhCH ₂ -, p-MeC ₆ H ₄ CH ₂ -, p-EtC ₆ H ₄ CH ₂ -, p- ⁱ PrC ₆ H ₄ CH ₂ -, p-i PrC 6 H 4 CH 2 - - ⁿ PrC ₆ H ₄ CH ₂ -, p- ⁿ BuC ₆ H ₄ CH ₂ - or p- ^t BuC ₆ H ₄ CH ₂ -.

Wherein, the group involved is abbreviated as the conventional group abbreviation in the field, such as Me is methyl, Et is ethyl, Pr is propyl, ⁱ Pr is isopropyl, ⁿ Pr is n-propyl, Bu is butyl , nBu is ⁿ -butyl, ^tBu is tert-butyl, Ph is phenyl, and Ar is aryl.

More preferably, X is selected from: trimethylsilylmethylene (-CH ₂ Si(CH ₃ ) ₃ ), bistrimethylsilylmethine (-CH[Si(CH ₃ ) ₃ ] ₂ ), Allyl (-CH ₂ CH=CH ₂ ), 2-methylallyl (-CH ₂ C(Me)=CH ₂ ), 1,3-bistrimethylsilyl allyl (-(SiMe) ₃ ) CHCH=CH(SiMe ₃ )), hexamethylsilamine group (-N[SiMe ₃ ] ₂ ), tetramethylsilylamino group (-N[SiMe ₂ H] ₂ ), methyl group (-CH ₃ ) ), benzyl (PhCH ₂ -), 4-methylbenzyl (p-MeC ₆ H ₄ CH ₂ -), 2-N,N'-dimethylbenzyl (-CH ₂ C ₆ H ₄ NMe ₂ -o), tetramethylaluminum (AlMe ₄ -), borohydride (BH ₄ -), hydrogen, chlorine or bromine.

Further preferably, X is selected from: trimethylsilylmethylene (-CH ₂ Si(CH ₃ ) ₃ ), allyl (-CH ₂ CH=CH ₂ ), 2-methylallyl (-CH 2 ) ₂ C(Me)=CH ₂ ), hexamethylsilamido (-N[SiMe ₃ ] ₂ ), tetramethylsilamido (-N[SiMe ₂ H] ₂ ), benzyl (PhCH ₂ -) , 4-methylbenzyl (p-MeC ₆ H ₄ CH ₂ -), 2-N,N'-dimethylbenzyl (-CH ₂ C ₆ H ₄ NMe ₂ -o), tetramethylaluminum (AlMe ₄ -), borohydride (BH ₄ -), hydrogen, chlorine or bromine.

Most preferably, X is selected from: trimethylsilylmethylene (-CH2Si( _CH3 ) ₃ ), allyl (-CH2CH= _CH2 ), ₂ -methylallyl ( _-CH2 ) ₂ C(Me)=CH ₂ ), tetramethylsilylamino (-N[SiMe ₂ H] ₂ ), benzyl (PhCH ₂ -), 4-methylbenzyl (p-MeC ₆ H ₄ CH _{2 )} -), _{2 -} N,N'-dimethylbenzyl ( _{-CH2C6H4NMe2 -} o) or hydrogen.

L is a neutral Lewis base chelating ligand, which is coordinated to the rare earth metal RE in the form of coordination bond. The L is selected from: tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether, pyridine or substituted pyridine. Wherein, n represents the number of ligands L, which is an integer from 0 to 2, including the endpoint value. In some embodiments of the present invention, the number n of ligands is 0 or 1.

RE is a rare earth element selected from lanthanides, scandium or yttrium. Preferably, RE is selected from scandium, yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, bait, ytterbium or lutetium. More preferably, RE is selected from: yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, bait or ytterbium. Most preferably, RE is selected from: yttrium, lanthanum, neodymium, gadolinium, holmium, bait or ytterbium.

More preferably, the catalyst represented by the formula I is selected from the compounds represented by the formula I-1 to the formula I-8:

The present invention also provides a preparation method of the catalyst described in the above technical scheme, comprising the following steps:

a) Ligand A reacts with alkyl alkali metal reagent MR ¹ to form alkali metal salt B;

b) mixed reaction of alkali metal salt B with rare earth halide RE(X') ₃ suspension and monoanionic alkali metal reagent MX to form a catalyst represented by formula I;

in:

In the MR ¹ , M is an alkali metal, and R ¹ is an alkyl group, a hydrogen or an amine group;

In the RE(X') ₃ , X' is a halogen element;

The solvent in the rare earth halide RE(X') ₃ suspension is a neutral Lewis base;

In the MX, M is an alkali metal, and X is the monoanionic ligand.

Regarding step a):

In the present invention, the source of the ligand A is not particularly limited, and can be a general commercial product or can be prepared according to a preparation method well known to those skilled in the art.

In the present invention, in the alkyl alkali metal reagent MR ¹ , M is an alkali metal, preferably Li, Na or K; R ¹ is an alkyl group, hydrogen or amine group. The alkyl alkali metal reagent MR ¹ is preferably one or more of n-butyllithium, sodium hydride, potassium hydride and benzyl potassium.

In the present invention, the molar ratio of the ligand A to the alkyl alkali metal reagent MR ¹ is preferably 1:2.

In the present invention, the reaction is preferably carried out under an inert atmosphere. In the present invention, there is no particular limitation on the type of inert gas for providing the inert atmosphere, and it may be conventional inert gas well known to those skilled in the art, such as nitrogen, argon or helium.

In the present invention, the temperature of the reaction is preferably 0-100°C, more preferably 0-60°C, and in some embodiments, the temperature is 0°C. The reaction time is preferably 10-600 min, more preferably 30-120 min.

In the present invention, the reaction is preferably carried out in a solvent medium, and specifically, the process of step a) is preferably as follows:

S1. Dissolve ligand A in a solvent to form a ligand solution;

S2, dissolving the alkyl alkali metal reagent MR ¹ in the solvent to form an alkyl alkali metal solution;

S3, mixing and reacting described ligand solution and alkyl alkali metal solution to form alkali metal salt B;

Wherein, step S1 and step S2 are not limited in order.

In the step S1: the solvent is preferably one or more of tetrahydrofuran, toluene, ether, n-hexane and 1,4-dioxane. The dosage ratio of the ligand A to the solvent is preferably 2 mmol:(2-20) mL.

In the step S2: the solvent is preferably one or more of n-hexane, toluene, ether, 1,4-dioxane and tetrahydrofuran. The dosage ratio of the alkyl alkali metal reagent MR ¹ to the solvent is preferably 4 mmol:(4-10) mL.

In the step S3: the temperature of the mixing reaction is preferably 0-100°C, more preferably 0-60°C, and in some embodiments, the temperature is 0°C. The reaction time is preferably 10-600 min, more preferably 30-120 min.

After the above reaction, the alkali metal salt B is formed.

Regarding step b):

In the present invention, in the rare earth halide RE(X′) ₃ , the type of rare earth element RE is the same as that of RE in Formula I in the above technical solution, and details are not repeated here. X' is a halogen element. In some embodiments of the present invention, the rare earth halide RE(X') ₃ is: YCl ₃ , LuCl _{3 , ErCl 3 , HoCl 3 , GdCl 3 , NdCl 3 ,} DyCl ₃ or LaBr ₃ .

The solvent in the rare earth halide RE(X′) ₃ solution is a neutral Lewis base, the type of which is the same as that of the neutral Lewis base ligand L in the formula I in the above technical solution, and will not be repeated here.

In the present invention, in the monoanionic alkali metal reagent MX, M is an alkali metal, preferably Li, Na or K; X is a monoanionic ligand, the type of which is the same as that of X described in formula I in the above technical scheme, here No longer.

In the present invention, the reaction is preferably carried out under an inert atmosphere. In the present invention, there is no particular limitation on the type of inert gas for providing the inert atmosphere, and it may be conventional inert gas well known to those skilled in the art, such as nitrogen, argon or helium.

In the present invention, the process of described step b) preferably comprises:

K1, the alkali metal salt B is dissolved in the solvent to obtain the alkali metal salt B solution;

K2. The rare earth halide RE(X') ₃ is mixed with a neutral Lewis base to obtain a rare earth halide RE(X') ₃ suspension;

K3. Dissolving the monoanionic alkali metal reagent MX in the solvent to obtain a monoanionic alkali metal reagent MX solution;

K4, mixing and reacting the alkali metal salt B solution with the rare earth halide RE(X') ₃ suspension to obtain an intermediate solution;

K5, mixing and reacting the intermediate solution with the monoanionic alkali metal reagent MX solution to form the catalyst shown in formula I;

Wherein, step K1, step K2 and step K3 are not limited in order.

In the step K1: the solvent is preferably one or more of tetrahydrofuran, toluene, ether, n-hexane and 1,4-dioxane. The dosage ratio of the alkali metal salt B to the solvent is preferably 2 mmol:(4-20) mL.

In the step K2: the type of the neutral Lewis base is the same as that of the neutral Lewis base ligand L in the formula I in the above technical solution, and details are not repeated here. The dosage ratio of the rare earth halide RE(X') ₃ to the neutral Lewis base is preferably 2 mmol:(2-30) mL.

In the step K3: the solvent is preferably one or more of n-hexane, toluene, diethyl ether, 1,4-dioxane and tetrahydrofuran. The dosage ratio of the monoanionic alkali metal reagent MX to the solvent is preferably 2 mmol:(2-10) mL.

The present invention does not limit the order of step K1, step K2 and step K3. In the subsequent reaction, the molar ratio of the alkali metal salt B to the rare earth halide RE(X') ₃ and the monoanionic alkali metal reagent MX is preferably controlled to be 1:(1-1.5):(1-1.5).

In the step K4: the temperature of the mixing reaction is preferably 0-100°C, more preferably 20-60°C, and in some embodiments, the temperature is 0°C. The reaction time is preferably 10 min to 12 h, more preferably 5 h.

In the step K5: the temperature of the mixing is preferably -30 to 100°C, more preferably 0°C. After the mixing is completed, the temperature is gradually raised to room temperature to continue the reaction; the room temperature may specifically be 20-30°C. After warming to room temperature, the reaction is continued for 0.5-12 h, more preferably 3 h. After the above reaction, the catalyst of formula I is formed in the system. In the present invention, after the above-mentioned reaction, preferably the following post-treatment is also carried out: vacuum distillation of the solvent, extraction, filtration, concentration and recrystallization, and after the above-mentioned post-treatment, the catalyst of formula I is obtained.

The present invention also provides a preparation method of styrene monomer isotactic polymer, comprising:

Under the action of the isotactic selective polymerization catalyst, the styrene monomer represented by the formula II undergoes a polymerization reaction to form the isotactic polymer represented by the formula III;

in,

R is a substituent group at the meta and/or para position on the benzene ring, m is the number of substituent groups R, 1≤m≤3;

R is selected from: C1-C20 alkoxy, C6-C20 aryloxy, C1-C20 alkylthio, C1-C20 silyl, C1-C40 alkyl, C3-C20 alkylsiloxy group, C2-C20 alkylamine group, hydrogen, chlorine, bromine or iodine;

The isotactic selective polymerization catalyst includes a main catalyst;

The main catalyst is the catalyst described in the above technical solutions.

In the present invention, in the styrene-based monomer represented by the formula II, R is a substituent group at the meta position and/or para position on the benzene ring, m is the number of substituent groups R, 1≤m≤3. The R is selected from: C1-C20 alkoxy, C6-C20 aryloxy, C1-C20 alkylthio, C1-C20 silyl, C1-C40 alkyl, C3-C20 alkyl Siloxy, C2-C20 alkylamine, hydrogen, chlorine, bromine or iodine.

Preferably, the styrene-based monomer represented by the formula II is selected from: styrene, p-methylstyrene, m-methylstyrene, 3,5-dimethylstyrene, 4-alkylstyrene, p-methylstyrene Methoxystyrene, p-methylthiostyrene, m-methoxystyrene, 3,5-dimethoxystyrene, p-fluorostyrene, m-fluorostyrene, p-alkoxystyrene, 2- Vinylnaphthalene, 6-methoxy-2-vinylnaphthalene, p-benzyloxystyrene, 4-(dimethylsilyl)styrene, 4-(trimethylsilyl)styrene, 4-( Buten-1)ylstyrene, 4-allylstyrene, 4-phenylacetylenestyrene, 4-butylacetylenestyrene, 4-vinylbenzocyclobutene, 4-(trimethylsilyl) Ethynyl)styrene, 4-alkylthiostyrene, 4-(silyl)styrene, 4-(N'N-dimethylamino)styrene, 4-(N'N-diethylamino) One or more of styrene and 4-(N'N-diphenylamino)styrene.

More preferably, the styrene-based monomer represented by the formula II is selected from: styrene, p-methylstyrene, m-methylstyrene, 3,5-dimethylstyrene, 4-alkylstyrene, p-methoxystyrene, p-methylthiostyrene, m-methoxystyrene, 3,5-dimethoxystyrene, p-fluorostyrene, m-fluorostyrene, p-alkoxystyrene, 2 -Vinylnaphthalene, 6-methoxy-2-vinylnaphthalene, p-benzyloxystyrene, 4-(dimethylsilyl)styrene, 4-(trimethylsilyl)styrene, 4- (Buten-1)ylstyrene, 4-allylstyrene, 4-phenylacetylenestyrene, 4-butylacetylenestyrene, 4-vinylbenzocyclobutene, 4-(trimethylstyrene) One or more of silylethynyl)styrene, 4-alkylthiostyrene and 4-(silyl)styrene.

In some embodiments of the present invention, the styrene-based monomer represented by the formula II is selected from one or more of the following compounds:

In the present invention, the catalyst of formula I can catalyze the isotactic selective homopolymerization of the same styrene monomer, and can also catalyze the isotactic selective copolymerization between different types of styrene monomers. Therefore, the styrene-based monomers represented by formula II can be the same or different, that is, they can be selected from one or more of the above-mentioned compounds.

In the present invention, the isotactic selective polymerization catalyst includes a main catalyst, and the main catalyst is the catalyst of formula I described in the above technical solution, which will not be repeated here. In the present invention, the molar ratio of the main catalyst to the styrene-based monomer represented by formula II is preferably 1:(50～100000), more preferably 1:(100～80000), still more preferably 1:(100～ 80000), most preferably 1:(2500～60000).

In the present invention, the catalyst of formula I can catalyze the polymerization of styrene monomers alone, or can jointly catalyze the isotactic selective polymerization of styrene monomers with the coordination of other cocatalysts. In the present invention, the cocatalyst preferably includes an organic boron salt and a main group metal alkyl compound.

The organic boron salt is preferably one of anion-containing organic boron salt, B(C ₆ F ₅ ) ₃ and 1,4-(C ₆ F ₅ ) ₂ BC ₆ F ₄ B(C ₆ F ₅ ) ₂ or several; wherein, in the organic boron salt containing anion, the anion is preferably [B(C ₆ F ₅ ) ₄ ] ^- or [1,4-(C ₆ F ₅ ) ₃ BC ₆ F ₄ B(C ₆ F ₅ ) ₃ ] ^2– . The organoboron salt is more preferably [NHEt ₃ ][B(C ₆ F ₅ ) ₄ ], [Ph ₃ C][B(C ₆ F ₅ ) ₄ ], [PhNMe ₂ H][B(C ₆ F ] ₅ ) ₄ ], B(C ₆ F ₅ ) ₃ , 1,4-(C ₆ F ₅ ) ₂ BC ₆ F ₄ B(C ₆ F ₅ ) ₂ and [Ph ₃ C] ₂ [1,4-( One or more of C ₆ F ₅ ) ₃ BC ₆ F ₄ B(C ₆ F ₅ ) ₃ ].

The main group metal alkyl compound is preferably one or more of alkyl aluminum, alkyl magnesium and alkyl zinc.

Wherein, the alkyl aluminum is preferably trimethyl aluminum, triethyl aluminum, tri-n-butyl aluminum, tri-n-propyl aluminum, triisobutyl aluminum, triisopropyl aluminum, tripentyl aluminum, trihexyl aluminum Aluminum, trioctylaluminum, diethylaluminum hydride, diisobutylaluminum hydride, methylaluminoxane (i.e. MAO), dried aluminoxane (i.e. DMAO) and modified alumoxane (and MMAO) one or more of them. More preferably among trimethylaluminum, triethylaluminum, tri-n-butylaluminum, tri-n-propylaluminum, triisobutylaluminum, triisopropylaluminum, diethylaluminum hydride and diisobutylaluminum hydride one or more of them. Most preferably, it is one or more of trimethylaluminum, triethylaluminum, triisobutylaluminum, triisopropylaluminum, diethylaluminum hydride and diisobutylaluminum hydride.

The alkyl zinc is preferably diethyl zinc.

The alkylmagnesium is preferably one or more of diethylmagnesium, di-n-propylmagnesium, diisopropylmagnesium and dibutylmagnesium; more preferably dibutylmagnesium.

In the present invention, the molar ratio of the main catalyst, the organic boron salt and the main group metal alkyl compound is preferably 1:(0-1):(0-1000).

In the present invention, the polymerization reaction may be bulk polymerization or polymerization in an organic solvent. When an organic solvent is used, the process is preferably as follows: first, the isotactic selective polymerization catalyst is dissolved in the organic solvent, and then the styrene-based monomer represented by formula II is added to carry out the reaction. In the present invention, the organic solvent is preferably one or more of an alkane solvent and an aromatic hydrocarbon solvent; more preferably one or more of a saturated straight-chain alkane, a saturated cycloalkane, an aromatic hydrocarbon and a halogenated aromatic hydrocarbon; Most preferably, it is one or more of n-hexane, decalin, cyclohexane, petroleum ether, benzene, toluene and xylene. The dosage ratio of the isotactic selective polymerization catalyst and the organic solvent is preferably 10 μmol:(0.5-10) mL.

In the present invention, the temperature of the polymerization reaction is preferably 0 to 160°C, more preferably 20 to 140°C, further preferably 40 to 120°C, and most preferably 60 to 120°C. The time of the polymerization reaction is preferably 1min-100h, more preferably 1min-72h, further preferably 1min-48h, most preferably 2min-12h. After the polymerization reaction, an isotactic polymer represented by formula III is generated;

Wherein, R and m are the same as those described in formula II in the above technical solution, and are not repeated here. n ₁ is the degree of polymerization.

In the present invention, by the above preparation method, isotactic polystyrene functionalized with meta- and/or para-polar groups is prepared for the first time (except isotactic poly-polar styrene protected by bulky groups). The number average molecular weight of the isotactic polymer obtained by the present invention is 1000g/mol～500× ¹⁰⁴ g/mol, preferably 2000g/mol～200× ¹⁰⁴ g/mol, more preferably 5000g/mol～100×10 ⁴ g/mol, most preferably 10000 g/mol to 50×10 ⁴ g/mol. The isotactic styrene monomer polymer prepared by the present invention can be an isotactic homopolymer of styrene monomer, or can be an isotactic copolymer of different styrene monomers. Wherein, the content of each styrene-based monomer structural unit in the isotactic copolymer of styrene-based monomers is selected from 0.1 mol% to 99 mol%. The isotacticity mm of the isotactic polymer prepared by the invention is more than 98%. Stereoregularity refers to the mole percent of tactical polymer in the total polymer.

The present invention also provides an isotactic polymer of styrene-based monomers prepared by the preparation method described in the above technical solutions.

In order to further understand the present invention, the preferred embodiments of the present invention are described below with reference to the examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

Example 1: Preparation of catalyst represented by formula I-1

1. The synthetic route is as follows:

2. The synthesis process is as follows:

S1, under an inert atmosphere, dissolve 2mmol of Ligand A in 10mL of tetrahydrofuran solvent to obtain a dissolving solution of Ligand A; The total volume of the solution was 2.5 mL) was gradually added to the above dissolving solution, and reacted for 30 min to obtain the ligand lithium salt reaction solution 1.

S2. Under an inert atmosphere, 2 mmol of YCl ₃ and 10 mmol of tetrahydrofuran (ie THF) were stirred at room temperature (20° C.) for 4 h to obtain a suspension of YCl ₃ in tetrahydrofuran.

S3. Mix the above-mentioned ligand lithium salt reaction solution 1 with the tetrahydrofuran suspension of YCl ₃ at 0° C., and react for 5 h; after that, add the n-hexane solution of alkyl lithium LiCH ₂ SiMe ₃ into the system (the alkyl lithium content is 2mmol, the total volume of the solution is 5mL), gradually warmed up to room temperature (20°C) and continued to react for 6h; after the reaction, all solvents were removed in vacuo, extracted with toluene, filtered, concentrated, and finally recrystallized at -30°C to obtain formula I- The catalyst shown in 1 has a product yield of 75% and a purity of >95%.

The product obtained in Example 1 was detected by 1H NMR (400 Hz, 25° C., CDCl ₃ ), and the results were shown in FIG. 1 , which is the 1H NMR spectrum of the catalyst of formula I-1 obtained in Example 1.

Example 2: Preparation of catalyst represented by formula I-2

According to the preparation process of Example 1, the difference is: the rare earth halide YCl ₃ in step S2 is replaced with LuCl ₃ , and the alkyl lithium LiCH ₂ SiMe ₃ in step S3 is replaced with LiCH ₂ Ph. The catalyst of formula I-2 was obtained with a product yield of 72% and a purity of >95%.

Example 3: Preparation of catalyst represented by formula I-3

According to the preparation process of Example 1, the difference is: the rare earth halide YCl ₃ in step S2 is replaced by ErCl ₃ , and the alkyl lithium LiCH ₂ SiMe ₃ in step S3 is replaced by KCH ₂ (C ₆ H ₄ ) _CH3 . The catalyst of formula I-3 was obtained with a product yield of 81% and a purity of >95%.

Example 4: Preparation of catalyst represented by formula I-4

According to the preparation process of Example 1, the difference is: the rare earth halide YCl ₃ in step S2 is replaced with HoCl ₃ . The catalyst of formula I-4 was obtained, the product yield was 75%, and the purity was >95%.

Example 5: Preparation of catalyst represented by formula I-5

According to the preparation process of Example 1, the difference is: the rare earth halide YCl ₃ in step S2 is replaced with GdCl ₃ . The catalyst of formula I-4 was obtained with a product yield of 68% and a purity of >95%.

Example 6: Preparation of catalyst represented by formula I-6

According to the preparation process of Example 1, the difference is: the rare earth halide YCl ₃ in step S2 is replaced with NdCl ₃ . The catalyst of formula I-6 was obtained with a product yield of 67% and a purity of >95%.

Example 7: Preparation of catalyst represented by formula I-7

According to the preparation process of Example 1, the difference is: the rare earth halide YCl ₃ in step S2 is replaced with DyCl ₃ . The catalyst of formula I-7 was obtained with a product yield of 70% and a purity of >95%.

Example 8: Preparation of catalyst represented by formula I-8

According to the preparation process of Example 1, the difference is: the rare earth halide YCl ₃ in step S2 is replaced by LaBr ₃ , and the alkyl lithium LiCH ₂ SiMe ₃ in step S3 is replaced by LiCH ₂ (C ₆ H ₄ ) N( _CH3 ) ₂ -o. The catalyst of formula I-8 was obtained, the product yield was 64%, and the purity was >95%.

The catalyst structures prepared in Examples 1 to 8 are as follows:

Polymerization Example 1

Under an inert atmosphere, 10 μmol of the catalyst of formula I-1 was dissolved in 0.5 mL of toluene in a reaction flask, then 10 mmol of styrene monomer was added to the reaction flask, and reacted in an oil bath at 80 °C for 15 min; after that, acidified with hydrochloric acid. Then the obtained product was stirred in ethanol at room temperature (20°C) to form a white solid powder, the solid product was collected by suction filtration with a Bush funnel, and dried in a vacuum drying oven at 60°C to constant weight, Polystyrene is obtained.

After testing, the conversion rate of styrene monomer is 100%, the isotacticity (mmmm)>99%, the molecular weight M _n =6.74×10 ⁴ g/mol, the molecular weight distribution M _w / _Mn =2.54, melting Temperature _Tm = 219°C.

Polymerization Examples 2 to 16

According to the preparation process of polymerization example 1, the difference is that the type of catalyst used, the type of monomer, [St]:[RE] (that is, the molar ratio of styrene monomer to catalyst of formula I), polymerization temperature and time have The difference, other conditions are the same as the polymerization example 1, see Table 1 for details. The products of each polymerization example were detected, and the results are shown in Table 1.

The structure of the styrene-based monomer used in each polymerization example is as follows:

Table 1 Reaction conditions and product characteristics of polymerization examples 1-16

Note: The molecular weight and molecular weight distribution were measured by GPC, and the stereoselectivity was determined according to the H NMR and C NMR spectra of the polymer.

Among them, the results of carbon nuclear magnetic resonance spectroscopy (100 Hz, 25° C., CDCl ₃ ) of the polymers obtained in Polymerization Examples 6 to 10 are shown in Figures 2 to 6, respectively; wherein, Figure 2 is the nuclear magnetic resonance of the polymers obtained in Polymerization Example 6. Figure 3 is the carbon nuclear magnetic resonance spectrum of the polymer obtained in the polymerization example 7, Figure 4 is the carbon nuclear magnetic resonance spectrum of the polymer obtained in the polymerization example 8, and Figure 5 is the polymer obtained in the polymerization example 9. C nuclear magnetic resonance spectrum, FIG. 6 is the carbon nuclear magnetic resonance spectrum of the polymer obtained in Polymerization Example 10.

Polymerization Example 17

Under an inert atmosphere, 10 μmol of the catalyst of formula I-6 and 100 μmol of AliBu ₃ were dissolved in 5 mL of toluene in a reaction flask, then 50 mmol of styrene monomer was added to the reaction flask, and the reaction was carried out in an oil bath at 80 °C for 120 min; ethanol acidified with hydrochloric acid to terminate the polymerization reaction; then, after stirring the obtained product in ethanol at room temperature (20°C) to form a white solid powder, the solid product was collected by suction filtration with a Bush funnel, and dried in a vacuum drying oven at 60°C to Constant weight to obtain polystyrene.

After testing, the conversion rate of styrene monomer was 97%, the isotacticity (mmmm)>99%, the molecular weight _Mn =46.7×10 ⁴ g/mol, and the molecular weight distribution M _w / _Mn =2.45.

Polymerization Example 18

Under an inert atmosphere, 10 μmol of the catalyst of formula I-6 and 100 μmol of AliBu ₃ were dissolved in 5 mL of toluene in a reaction flask, and then 25 mmol of styrene monomer and 25 mmol of p-methoxystyrene monomer were added to the reaction flask, and the mixture was heated at 80 The reaction was carried out in an oil bath for 240 min; after that, ethanol acidified with hydrochloric acid was added to terminate the polymerization reaction; then, the obtained product was stirred into a white solid powder in ethanol at room temperature (20 °C), and the solid product was collected by suction filtration with a Bush funnel. , and dried to constant weight in a vacuum drying oven at 60 °C to obtain a polymer.

After testing, the conversion rate of the monomer is 87%; the molar content of p-methoxystyrene unit is 43mol%, the isotacticity mm>99%, the molecular weight M _n =38.7×10 ⁴ g/mol, the molecular weight Distribution M _w / _Mn = 2.11.

The structure of the resulting polymer is roughly represented by the following formula:

Polymerization Example 19

Under an inert atmosphere, 10 μmol of the catalyst of formula I-6 and 100 μmol of AliBu ₃ were dissolved in 5 mL of toluene in a reaction flask, and then 25 mmol of styrene monomer and 25 mmol of p-methylthiostyrene monomer were added to the reaction flask. The reaction was carried out in an oil bath for 120 min; after that, ethanol acidified with hydrochloric acid was added to terminate the polymerization reaction; then, the obtained product was stirred into a white solid powder in ethanol at room temperature (20° C.), and the solid product was collected by suction filtration with a Bush funnel. and dried to constant weight in a vacuum drying oven at 60°C to obtain a polymer.

The obtained product was detected by carbon nuclear magnetic resonance (100 Hz, 25° C., CDCl ₃ ). The results are shown in FIG. 3 , which is the carbon nuclear magnetic resonance spectrum of isotactic poly-p-methylthiostyrene obtained in Polymerization Example 19.

After testing, the conversion rate of the monomer is 97%; the molar content of p-methylthiostyrene unit is 47mol%, the isotacticity mm>99%, the molecular weight M _n =40.7×10 ⁴ g/mol, the molecular weight Distribution M _w / _Mn = 2.31.

Polymerization Example 20

Under an inert atmosphere, 10 μmol of formula I-6 catalyst and 100 μmol of AliBu ₃ were dissolved in 5 mL of toluene in a reaction flask, and then 25 mmol of m-methoxystyrene monomer and 25 mmol of p-methylthiostyrene monomer were added to the reaction flask. , reacted in an oil bath at 80 °C for 480 min; after that, added ethanol acidified with hydrochloric acid to terminate the polymerization reaction; then, at room temperature (20 °C), the resulting product was stirred into a white solid powder in ethanol, and filtered with a Bush funnel. The solid product was collected and dried to constant weight in a vacuum oven at 60°C to obtain a polymer.

The obtained product was detected by carbon nuclear magnetic resonance (100 Hz, 25° C., CDCl ₃ ), and the results are shown in FIG.

After testing, the conversion rate of the monomer is 89%; the molar content of p-methylthiostyrene unit is 54mol%, the isotacticity mm>99%, the molecular weight M _n =38.7×10 ⁴ g/mol, the molecular weight Distribution M _w / _Mn = 2.28.

The descriptions of the above embodiments are only used to help understand the method and the core idea of the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A catalyst having the structure of formula i:

wherein:

x is a monoanionic ligand selected from: C1-C16 alkyl, C4-C16 silyl, C2-C16 alkylamino, C4-C20 alkylsilamino, C6-C20 arylamine, substituted or unsubstituted C3-C10 allyl, C7-C20 arylmethylene, boron hydride, tetramethyl aluminum, hydrogen, chlorine, bromine or iodine;

l is a neutral lewis base chelating ligand selected from: tetrahydrofuran, diethyl ether, ethylene glycol dimethyl ether, pyridine or substituted pyridines; n represents the number of ligands and is an integer of 0-2;

RE is a rare earth element selected from: lanthanide, scandium or yttrium.

2. The catalyst according to claim 1,

the alkyl of C1-C16 is selected from: methyl, ethyl, n-propyl, isopropyl, n-butyl, or n-octyl;

the silane group of C4-C16 is selected from: -CH₂Si(CH₃)₃、-CH[Si(CH₃)₃]₂、-CH₂Si(CH₃)₂Ph or-CH₂SiMe₂C₆H₄OMe-o；

The alkyl amino of C2-C16 is selected from: -NMe₂、-NEt₂、-NⁿPr₂、-NⁱPr₂or-NⁿBu₂；

The alkyl silamine group of C4-C20 is selected from: -N [ SiMe ]₃]₂or-N [ SiMe ]₂H]₂；

The arylamine group of C6-C20 is selected from: -CH₂C₆H₄NMe₂-o、-NHPh、-NHC₆H₄Me-p、-NHC₆H₄ ⁱPr-p or-NHC₆H₄(ⁱPr)₂-2,6；

The substituted or unsubstituted C3-C10 allyl is selected from: -CH₂CH＝CH₂、-CH₂C(Me)＝CH₂、-(SiMe₃)CHCH＝CH(SiMe₃)；

The arylmethylene of C7-C20 is selected from: p-MeC₆H₄CH₂-、p-EtC₆H₄CH₂-、p-ⁱPrC₆H₄CH₂-、p-ⁿPrC₆H₄CH₂-、p-ⁿBuC₆H₄CH₂-or p-^tBuC₆H₄CH₂-；

The RE is selected from: scandium, yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, erbium, ytterbium or lutetium.

3. The catalyst according to claim 1, wherein X is selected from the group consisting of: trimethylsilylmethylene, bistrimethylsilylmethine, allyl, 2-methylallyl, 1, 3-bistrimethylsilylallyl, hexamethylsilylamino, tetramethylsilylamino, methyl, benzyl, 4-methylbenzyl, 2-N, N' -dimethylbenzyl, tetramethylaluminum, borohydride, hydrogen, chlorine or bromine;

the RE is selected from: yttrium, lanthanum, neodymium, gadolinium, dysprosium, holmium, erbium or ytterbium.

4. The catalyst according to claim 1, wherein X is selected from the group consisting of: trimethylsilylidene, allyl, 2-methylallyl, hexamethyl-silylamine, tetramethylsilylamine, benzyl, 4-methylbenzyl, 2-N, N' -dimethylbenzyl, tetramethylaluminum-based, or hydrogen;

the RE is selected from: yttrium, lanthanum, neodymium, gadolinium, holmium, erbium or ytterbium.

5. The catalyst of claim 1, selected from the group consisting of compounds of formula i-1 to formula i-8:

6. a method for preparing the catalyst according to any one of claims 1 to 5, comprising the steps of:

a) ligand A and alkyl alkali metal reagent MR¹Reacting to form an alkali metal salt B;

b) alkali metal salt B with rare earth halide RE (X')₃Mixing the suspension and a monoanionic alkali metal reagent MX for reaction to form a catalyst shown as a formula I;

wherein:

the MR¹In which M is an alkali metal, R¹Is alkyl, hydrogen or amino;

the RE (X')₃Wherein, X' is a halogen element;

the rare earth halide RE (X')₃The solvent in the suspension is neutral Lewis base;

in MX, M is an alkali metal, and X is a monoanionic ligand.

7. A method for preparing a styrene monomer isotactic polymer is characterized by comprising the following steps:

under the action of an isotactic selective polymerization catalyst, carrying out polymerization reaction on a styrene monomer shown in a formula II to form an isotactic polymer shown in a formula III;

wherein,

r is a substituent group at meta position and/or para position on a benzene ring, m is the number of the substituent group R, and m is more than or equal to 1 and less than or equal to 3;

r is selected from: C1-C20 alkoxy, C6-C20 aryloxy, C1-C20 alkylthio, C1-C20 silyl, C1-C40 alkyl, C3-C20 siloxy, C2-C20 alkylamino, hydrogen, chlorine, bromine or iodine;

the isotactic selective polymerization catalyst comprises a main catalyst;

the main catalyst is the catalyst according to any one of claims 1 to 5.

8. The method according to claim 7, wherein the styrenic monomer is selected from the group consisting of: styrene, p-methylstyrene, m-methylstyrene, 3, 5-dimethylstyrene, 4-alkylstyrene, p-methoxystyrene, p-methylthiostyrene, m-methoxystyrene, 3, 5-dimethoxystyrene, p-fluorostyrene, m-fluorostyrene, p-alkoxystyrene, 2-vinylnaphthalene, 6-methoxy-2-vinylnaphthalene, p-benzyloxystyrene, 4- (dimethylsilyl) styrene, 4- (trimethylsilyl) styrene, 4- (buten-1) ylstyrene, 4-allylstyrene, 4-phenylacetylenestyrene, 4-butylacetylenestyrene, 4-vinylbenzocyclobutene, 4- (trimethylsilylethynyl) styrene, 4-alkylthiostyrene, styrene, one or more of 4- (silyl) styrene, 4- (N ' N-dimethylamino) styrene, 4- (N ' N-diethylamino) styrene and 4- (N ' N-diphenylamino) styrene;

the isotactic polymerization catalyst further comprises a cocatalyst;

the cocatalyst comprises an organic boron salt and a main group metal alkyl compound;

the temperature of the polymerization reaction is 0-160 ℃, and the time is 1 min-100 h;

the molar ratio of the main catalyst to the organic boron salt to the main group metal alkyl compound is 1 to (0-1) to (0-1000);

the molar ratio of the main catalyst to the styrene monomer shown in the formula II is 1: 50-100000.

9. The method according to claim 8, wherein the styrenic monomer is selected from the group consisting of styrene, p-methylstyrene, m-methylstyrene, 3, 5-dimethylstyrene, 4-alkylstyrene, p-methoxystyrene, p-methylthiostyrene, m-methoxystyrene, 3, 5-dimethoxystyrene, p-fluorostyrene, m-fluorostyrene, p-alkoxystyrene, 2-vinylnaphthalene, 6-methoxy-2-vinylnaphthalene, p-benzyloxystyrene, 4- (dimethylsilyl) styrene, 4- (trimethylsilyl) styrene, 4- (buten-1) ylstyrene, 4-allylstyrene, 4-phenylacetylenestyrene, 4-butylacetylenestyrene, 4-vinylbenzocyclobutene, and the like, One or more of 4- (trimethylsilylethynyl) styrene, 4-alkylthio styrene and 4- (silyl) styrene;

the organoboron salt is selected from: [ NHEt₃][B(C₆F₅)₄]、[Ph₃C][B(C₆F₅)₄]、[PhNMe₂H][B(C₆F₅)₄]、B(C₆F₅)₃、1,4-(C₆F₅)₂BC₆F₄B(C₆F₅)₂And [ Ph₃C]₂[1,4-(C₆F₅)₃BC₆F₄B(C₆F₅)₃]One or more of the above;

the main group metal alkyl compound is selected from one or more of alkyl aluminum, alkyl magnesium and alkyl zinc.

10. The preparation method according to claim 9, wherein the alkyl aluminum is selected from one or more of trimethyl aluminum, triethyl aluminum, tri-n-butyl aluminum, tri-n-propyl aluminum, triisobutyl aluminum, triisopropyl aluminum, tripentyl aluminum, trihexyl aluminum, trioctyl aluminum, diethyl aluminum hydride and diisobutyl aluminum hydride;

the alkyl zinc is diethyl zinc;

the alkyl magnesium is selected from one or more of diethyl magnesium, di-n-propyl magnesium, diisopropyl magnesium and dibutyl magnesium;

the molar ratio of the main catalyst to the organic boron salt to the main group metal alkyl compound is 1 to (0-1) to (0-500);

the molar ratio of the main catalyst to the styrene monomer shown in the formula II is 1: 100-80000.

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