CN104370681A - Synthesis method of vinyl-bridged dialkylindene compound - Google Patents

Abstract

The invention relates to a synthesis method of a vinyl-bridged dialkylindene compound, which comprises mixing indene or an alkyl substituent of indene with an alkyl lithium salt in an alkane solution, and reacting to prepare indene or an alkyl-substituted indenyllithium Salt alkane solution; then add o-dibromoalkane to form a miscible solution, and then add an activator to synthesize a vinyl-bridged dialkylindene compound; the synthesis process conditions are mild, avoiding the use of low-temperature reactions, and operability Strong, high yield, conducive to industrial production.

Description

A kind of synthetic method of vinyl bridged dialkyl indene compound

technical field

The invention relates to a synthesis method of a vinyl bridged dialkylindene compound, belonging to the field of chemical synthesis.

Background technique

Metallocenes are organometallic coordination compounds formed by linking transition metals with cyclopentadiene and its derivatives. This type of catalyst has a single active site, and the molecular weight distribution of the polymerization product is relatively narrow, with ideal physical and chemical properties. Metallocene catalyst compounded with activator N,N-dimethylphenyl tetrakis (pentafluorophenyl) borate, co-activator triisobutylaluminum or compounded with methylaluminoxane (MAO) The catalytic system has very high catalytic activity in polymerization reactions such as ethylene polymerization and ethylene-propylene copolymerization, and it has become a hot spot that people have paid attention to in recent years. Vinyl-bridged diindenyl compounds are important intermediates for the synthesis of metallocene catalysts. The metallocene catalysts synthesized with 1,2-diindenyl ethane and its homologues as ligands are vinyl-bridged diindenyl dichlorides. Zirconium oxide is widely used in olefin polymerization, and its general structural formula is shown in Formula 1.

In the formula, R ¹ , R ² , R ³ , and R ⁴ are H atoms or C ₁ -C ₆ alkyl groups, R ⁵ , R ⁶ are respectively selected from H and C ₁ -C ₄ alkyl groups, and R ⁵ and R The sum of ⁶ carbon atoms is not more than 4.

At present, there are many patents and documents describing the synthesis method of 1,2-diindane, for example: in J.Organometallic Chemistry, 342 (1988) 21-29, S.Collins et al. introduced a method using 1, The method of synthesizing 1,2-diindenyl ethane from 2-dibromoethane: using two equal parts of indenyllithium and 1,2-dibromoethane in THF/HMPA solution, slowly heating from -78°C to The reaction was carried out at room temperature, and the yield of the final product obtained after recrystallization from acetone/ethanol was 65%.

In J.Am.Chem.Soc., 109 (1987) 6544-6545, people such as A.Ewen adopt the method similar to Collins, in tetrahydrofuran (THF) solution, also use two equal parts of indenyllithium and 1 , 2-dibromoethane was slowly heated from -90°C to 25°C for reaction, and the yield of the final product obtained after ethanol recrystallization was 60%.

In the patent EP-A-0485823, Hoechst adopted a method similar to that of Collins, changed the reaction solution, and used THF as the solvent. After stirring the solution for 5 hours, the solution was slowly raised from -78°C to room temperature, and passed through the column. Chromatographic separation and purification gave 49% yield of 1,2-bis(2-methylindene)ethane.

In patent EP-A-0575875, Spherilene uses 4,7-dimethylindene as a starting material, and after the solution is heated from -78°C to 50°C and stirred for 12 hours, a 48% impure product is obtained.

In the document Organometallics, 10 (1991), Grossman et al. obtained 54% of 1 with the ratio of indenyllithium to 1,2-dibromoethane at 2.2:1 and the reaction temperature at -78°C to room temperature. , 2-diindene ethane.

All there is obvious shortcoming in the reaction process of above-mentioned reaction, and the yield of these synthetic reactions is generally on the low side, does not exceed 65%, and wherein main by-product is spiroindene compound, because the property of impurity and product is close, needs to use column Chromatographic separation method is used for separation and purification, which is not desirable in industry. In addition, in order to suppress the formation of by-products, these reactions are carried out at low temperature or even ultra-low temperature. Creating and maintaining low temperature reaction conditions in large-scale industrial production requires a lot of energy, which is uneconomical in production. . For this reason, it is particularly important to improve the above-mentioned reaction, increase reaction efficiency, reduce reaction energy consumption, and increase its economy.

The present invention increases the reaction temperature by improving the reaction solvent system and the method of adding an activator, so that the reaction can be carried out at normal temperature, reduces the production of by-products, greatly improves the yield of the product, and is a vinyl-bridged The industrial synthesis of dialkylindenes provides a new way.

Contents of the invention

The object of the present invention is to provide a method for synthesizing vinyl-bridged dialkylindene compounds, which has the characteristics of mild reaction conditions and high yield, and helps to realize the industrialized production of vinyl-bridged dialkylindene compounds .

The present invention is achieved through the following technical solutions:

A kind of synthetic method of the dialkyl indene compound of vinyl bridge, comprises the following steps:

(1) Under the protection of an inert gas, indene or an alkyl substituent of indene reacts with an alkyl lithium in an alkane solvent to prepare an alkane solution of an indenyl lithium salt or an alkyl-substituted indenyl lithium salt;

(2) under the protection of an inert gas, add o-dibromoalkane in the above-mentioned alkane solution prepared, stir to form a uniform mixed solution;

(3) Under the protection of an inert gas, an activator is added dropwise in the above mixed solution to react to synthesize a vinyl-bridged dialkylindene compound;

Wherein, R is methyl, n-butyl or tert-butyl; R ¹ , R ² , R ³ , R ⁴ are selected from H and C ₁ -C ₆ alkyl groups respectively; R ⁵ , R ⁶ are selected from H and C ₁ -C ₄ alkyl, and the sum of R ⁵ and R ⁶ carbon atoms is not more than 4.

Preferably, the reaction temperature in step (1) is 0-100° C.; the reaction time is 1-8 hours.

More preferably, the reaction temperature in step (1) is room temperature (25° C.); the reaction time is 2-4 hours.

Preferably, the inert gas is selected from high-purity nitrogen, high-purity argon and high-purity helium.

Preferably, in step (1), the alkane solvent is selected from n-pentane, n-hexane, n-heptane, n-octane and petroleum ether. The reaction of step (1) is not suitable for the use of strong polar solvents.

Preferably, in step (1), the mass ratio of the alkane solvent to indene or an alkyl substituent of indene is 5-50:1.

Preferably, in step (1), the molar ratio of the alkyllithium to indene or the alkyl substituent of indene is 1-1.5:1; more preferably 1:1.

Preferably, in step (2), the molar ratio of the o-dibromoalkane to indene or an alkyl substituent of indene is 0.5-0.8:1.

Preferably, in step (3), the activator is selected from diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, 2-methylfuran, 2,5-dimethylfuran, 2,3-benzofuran, etc. non-toxic solvents.

Preferably, in step (3), the molar ratio of the activator to the indene or the alkyl substituent of indene in step (1) is 0.1-1:1.

Preferably, in step (3), the rate of addition of the activator is controlled, the reaction temperature is controlled to be 0-100°C, and the reaction is continued for 1-8 hours after the addition of the activator is completed. In the initial stage of the reaction, the purpose of controlling the reaction temperature can be achieved by controlling the dropwise addition of the activator, and an external temperature control device is required to control the temperature after the addition is completed.

More preferably, in step (3), the activator is added dropwise within 1 hour, the reaction temperature is controlled at 35° C., and the reaction is continued for 2 hours after the activator is added dropwise.

Preferably, the method for synthesizing vinyl-bridged bis-indenyl compounds further includes the following steps: after the reaction, the product is washed with water, and then the solvent is evaporated, and then the product is recrystallized to obtain a white solid.

Preferably, the solvent for the recrystallization is a mixed solution of ethanol and toluene.

More preferably, the volume ratio of ethanol to toluene is 1-4:1.

The advantages of the present invention are:

1) This synthetic route does not require low-temperature reaction conditions, and can be carried out at room temperature, which greatly reduces the energy consumption of the reaction, making the industrial production of this route possible;

2) The method of dripping an activator is used in the present invention to control the reaction rate, so that the reaction rate is gentle and controllable;

3) Adopting this method to synthesize vinyl-bridged dialkylindene compounds does not produce by-product spiroindene, and the product is easy to separate and purify;

4) The yield of the product in the present invention can reach up to 80%, which is higher than that of various existing synthetic methods.

Detailed ways

The technical solutions of the present invention are illustrated below through specific examples. It should be understood that one or more method steps mentioned in the present invention do not exclude that there are other method steps before and after the combined steps or other method steps can be inserted between these explicitly mentioned steps; it should also be understood that these The examples are only for illustrating the present invention and are not intended to limit the scope of the present invention. Moreover, unless otherwise stated, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the sequence of each method step or limit the scope of the present invention. The change or adjustment of its relative relationship is in In the case of no substantive change in the technical content, it shall also be regarded as the applicable scope of the present invention.

The invention provides a kind of synthetic method of the dialkylindene compound of vinyl bridging, comprises the following steps:

(1) Under the protection of an inert gas, indene or an alkyl substituent of indene reacts with an alkyl lithium in an alkane solvent to prepare an alkane solution of an indenyl lithium salt or an alkyl-substituted indenyl lithium salt;

(2) under the protection of an inert gas, add o-dibromoalkane in the above-mentioned alkane solution prepared, stir to form a uniform mixed solution;

(3) Under the protection of an inert gas, an activator is added dropwise in the above mixed solution to react to synthesize a vinyl-bridged dialkylindene compound;

Wherein, R is methyl, n-butyl or tert-butyl; R ¹ , R ² , R ³ , R ⁴ are selected from H and C ₁ -C ₆ alkyl groups respectively; R ⁵ , R ⁶ are selected from H and C ₁ -C ₄ alkyl, and the sum of R ⁵ and R ⁶ carbon atoms is not more than 4;

In step (1), the mass ratio of the alkane solvent to indene or the alkyl substituent of indene is 5-50:1. The molar ratio of the alkyllithium to indene or the alkyl substituent of indene is 1-1.5:1; more preferably 1:1. The reaction temperature of step (1) can be 0-100°C, and the reaction time can be 1-8 hours; but from the economic and industrial point of view, the step (1) of the present invention is preferably carried out at room temperature, and the reaction time is 2-4 hours. The alkane solvent in step (1) can be selected from any or any combination of n-pentane, n-hexane, n-heptane, n-octane and petroleum ether. But step (1) is not suitable to adopt strong polar solvent.

In step (2), the molar ratio of the o-dibromoalkane to indene or the alkyl substituent of indene is 0.5-0.8:1; first pass through step (2), and the indenyl lithium prepared in step (1) Salt or alkyl substituted indenyllithium salt alkane solution, add o-dibromoalkane, stir to form a uniform mixed solution; key point.

The activator in step (3) is selected from polar solvents such as diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, dimethylfuran, 2,5-dimethylfuran, and 2,3-benzofuran. The molar ratio of the activator to the indene or the alkyl substituent of indene in step (1) is 0.1-1:1. In step (3), the dropping rate of the activator is controlled, the reaction temperature is controlled to be 0-100° C., and the reaction is continued for 1-8 hours after the addition of the activator is completed. By controlling the dropwise addition of the activator, the purpose of controlling the reaction temperature can be achieved. After the activator is added dropwise, external temperature control is required to keep the reaction at 0-100°C. More preferably, in step (3), the reaction temperature is controlled at 35° C., and the reaction is continued for 2 hours after the activator is added dropwise.

The method for synthesizing vinyl-bridged bis-indenyl compounds also includes the following steps: after the reaction, the product is washed with water, and then the solvent is evaporated, and then the product is recrystallized to obtain a white solid. The solvent for the recrystallization is a mixed solution of ethanol and toluene. More preferably, the volume ratio of ethanol to toluene is 1-4:1.

The technical scheme of the present invention is described below by specific implementation:

Embodiment 1 compound 1, the synthesis of 2-diindenyl ethane

(1) At room temperature (25°C), under the protection of a nitrogen atmosphere, weigh 111.6g (90wt%) of indene and add it to 1L of n-hexane, and measure 394ml of n-hexane solution of n-butyllithium with a molar concentration of 2.2mol/L, It was slowly added to the above solution, and after the dropwise addition was completed, the reaction was stirred for 2 hours to obtain a n-hexane solution of indenyllithium salt;

(2) At room temperature, under the protection of a nitrogen atmosphere, measure 38ml of dibromoethane and add it to the n-hexane solution of the above-mentioned indenyllithium salt, stir and mix evenly;

(3) Under the protection of nitrogen, slowly drop 20ml of THF into the above solution, control the reaction temperature to 35°C, and continue the reaction for 2 hours after the addition;

(4) After the reaction, wash with water three times, distill off the solvent, and recrystallize with a mixed solvent of toluene/ethanol with a volume ratio of 2:1 to obtain 90 g of white solid 1,2-diindene with a yield of 80.5%.

The NMR data of the product are: The product is characterized by ¹ H-NMR (CDCl ₃ as solvent, 25°C): δ=7.31(d, 1H), 7.28～7.13(m, 3H), 6.34(s, 1H), 2.1( s,1H)

Comparative example 1 compound 1, the synthesis of 2-diindene ethane

Weigh 111.6g (90wt%) of indene and add it into 1L tetrahydrofuran solution, measure the n-hexane solution of n-butyllithium with a molar concentration of 2.2mol/L, and slowly add it to the above solution at -78°C, After the dropwise addition, stir and react for 2 hours, add 36ml of dibromoethane to the above lithium salt solution, react for 2 hours, wash with water 3 times, evaporate the solvent, and recrystallize with ethanol/toluene mixed solvent with a volume ratio of 2:1 45 g of white solid 1,2-diindene was obtained with a yield of 40.5%.

The nuclear magnetic data that comparative example obtains product is the same as embodiment 1.

The THF that adopts in the comparative example is to add as reaction solvent, and adopts alkanes to carry out lithiation as reaction solvent in embodiment 1, add dibromoethane reaction violently after lithiation in THF, must carry out under ultra-low temperature, and side effect There are many reactions, but adding dibromoethane after lithiation in alkane solvents does not react. Adding a small amount of THF acts as a catalyst (activator), making the reaction controllable and stable at room temperature.

It can be seen from the above results that the metallocene ligand 1,2-diindene ethane can be obtained in high yield at room temperature by using the inventive synthetic method, avoiding the expensive solvent tetrahydrofuran and the harsh low-temperature reaction in the comparative example conditional use.

The synthesis of embodiment 2 compound 1,2-two (2,4-dimethylindene) ethane

(1) At room temperature, under the protection of a nitrogen atmosphere, weigh 14.4g of 2,4-dimethylindene and add it to 500mL of n-hexane solution, measure 100ml of the n-hexane solution of methyllithium with a molar concentration of 1mol/L, and Slowly added to the above solution, stirred and reacted for 3 hours after the dropwise addition, to obtain n-hexane solution of 2,4-dimethylindenyllithium salt;

(2) At room temperature, under the protection of a nitrogen atmosphere, measure 4.5ml of dibromoethane and add it to the n-hexane solution of the above-mentioned 2,4-dimethylindenyllithium salt, and stir and mix evenly;

(3) Under nitrogen protection, measure 3ml of THF and slowly add it dropwise to the above solution, control the reaction temperature to 35°C, and continue the reaction for 2 hours after the dropwise addition;

(4) After the reaction, wash with water three times, evaporate the solvent, and recrystallize with ethanol/toluene mixed solvent with a volume ratio of 2:1 to obtain white solid 1,2-bis(2,4-dimethylindene) Ethane 11.3g, yield 72%.

NMR data: The product was characterized by ¹ H-NMR (CDCl ₃ as solvent, 25°C): δ=7.28(d,1H),7.14(d,1H),6.97(t,1H),6.38(s,1H), 3.61(q,1H),2.31(s,3H),2.2(s,2H),1.54(d,3H)

Synthesis of embodiment 3 compound 1,2-two (2,4,7-trimethylindene) ethane

(1) At room temperature, under the protection of a nitrogen atmosphere, weigh 79g of 2,4,7-trimethylindene and add it to 500mL of n-heptane, and measure 500ml of n-pentane solution of methyllithium with a molar concentration of 1mol/L, It was slowly added to the above solution, and after the dropwise addition was completed, the reaction was stirred for 4 hours to obtain a mixed solution of n-heptane and n-pentane of 2,4,7-trimethylindenyllithium salt;

(2) At room temperature, under the protection of a nitrogen atmosphere, measure 34ml of dibromoethane and add it to the mixed solution of 2,4,7-trimethylindenyllithium in n-heptane and n-pentane, and stir and mix evenly;

(3) Under nitrogen protection, measure 15ml of THF and slowly add it dropwise to the above solution, control the reaction temperature at 35°C, and continue the reaction for 2 hours after the dropwise addition;

(4) After the reaction, wash with water three times, evaporate the solvent, and recrystallize with a mixed solvent of ethanol/toluene with a volume ratio of 4:1 to obtain a white solid 1,2-bis(2,4,7-trimethyl Indene) ethane 64.2g, yield 75%.

NMR data: The product was characterized by ¹ H-NMR (CDCl ₃ as solvent, 25°C): δ=7.01(d,1H),6.87(d,1H),6.11(s,1H),3.65(q,1H), 2.49(s,3H),2.34(s,3H),2.00(s,2H),1.54(d,3H)

Embodiment 4 compound 2, the synthesis of 3-diindenyl butane

(1) At room temperature, under the protection of a nitrogen atmosphere, weigh 55.8g (90wt%) of indene and add it to 500mL of n-hexane solution, measure 200ml of n-butyllithium n-hexane solution with a molar concentration of 2.2mol/L, and slowly Added to the above solution, stirred and reacted for 2 hours after the dropwise addition was completed, to obtain n-hexane solution of indenyllithium salt;

(2) At room temperature, under the protection of a nitrogen atmosphere, measure 46g of 2,3-dibromobutane and add it to the n-hexane solution of the indenyllithium salt, and stir and mix evenly;

(3) Under the protection of nitrogen, measure 20ml of 2-methylfuran and slowly add it dropwise to the above solution, control the reaction temperature to 35°C, and continue the reaction for 2h after the dropwise addition;

(4) After the reaction, wash with water for 3 times, evaporate the solvent, and recrystallize with a mixed solvent of toluene/ethanol with a volume ratio of 2:1 to obtain 43.9 g of white solid 2,3-diindane, with a yield of 71% .

The NMR data of the product are: The product is characterized by ¹ H-NMR (CDCl ₃ as solvent, 25°C): δ=7.31(d, 1H), 7.29～7.13(m, 3H), 6.32(s, 1H), 2.35( q,1H),1.12(d,3H)

Synthesis of embodiment 5 compound 1,2-two (3-1-hexylindene) ethane

(1) room temperature, under nitrogen atmosphere protection, weigh 20g of 1-hexylindene and add in 1.3L n-hexane solution, measure 100ml molar concentration and be the n-hexane solution of tert-butyllithium of 1mol/L, slowly add it to In the above solution, after the dropwise addition was completed, the reaction was stirred for 3 hours to obtain a n-hexane solution of 1-hexylindenyllithium salt;

(2) At room temperature, under the protection of a nitrogen atmosphere, measure 4.5ml of dibromoethane and add it to the n-hexane solution of the above-mentioned 1-hexylindenyllithium salt, stir and mix evenly;

(3) Under the protection of nitrogen, measure 10ml of 2,3-benzofuran and slowly add it dropwise to the above solution, control the reaction temperature at 35°C, and continue the reaction for 2 hours after the addition;

(4) After the reaction, wash with water three times, evaporate the solvent, and recrystallize with a mixed solvent of ethanol/toluene with a volume ratio of 2:1 to obtain a white solid 1,2-bis(3-1-hexylindene)ethane 15.36g, yield 72.1%.

NMR data: The product was characterized by ¹ H-NMR (CDCl ₃ as solvent, 25°C): δ=7.33(d, 1H), 7.27～7.20(m, 3H), 6.14(s, 1H), 3.45(q, 1H ),2,02(s,2H),1.62(m,2H),1.30～1.22(m,8H),0.85(t,3H).

Synthesis of embodiment 6 compound 1,2-diindenyl ethane

The synthesis conditions were the same as in Example 1 except that 20 ml of ethylene glycol dimethyl ether was added to the lithium salt solution as an activator in step (3). After the reaction was completed, 85.5 g of white solid 1,2-diindene was obtained. Yield 76.5%.

Example 7

The synthesis conditions were the same as in Example 1, except that tert-butyllithium in n-hexane solution was used in step (1). After the reaction was completed, 88.3 g of white solid 1,2-diindene was obtained with a yield of 79%.

NMR data is the same as in Example 1.

Embodiment 8 and Embodiment 9

Example 8 Step (1) Reaction temperature 0°C, Example 9 Step (1) Reaction temperature 100°C, other synthesis conditions are the same as Example 1. After the reaction is completed, Example 8 obtains white solid 1,2-diindene ethane 89g, yield 79.7%; Example 9 obtained 58g of white solid 1,2-diindane, yield 51.9%.

The nuclear magnetic data of embodiment 8 and embodiment 9 products are the same as embodiment 1.

Example 10 and Example 11

Example 10 step (3) reaction temperature 0 ° C, Example 11 step (3) reaction temperature 100 ° C; other synthesis conditions and Example 1, after the reaction, Example 1 to obtain white solid 1,2-diindene ethane 85g, yield 76.1%; Example 11 obtained 53g of white solid 1,2-diindane, yield 47.4%.

Embodiment 10 and embodiment 11 product NMR data are the same as embodiment 1.

Example 12

The synthesis conditions were the same as in Example 1, except that 394 ml of n-butyllithium in n-hexane with a concentration of 3.2 mol/L was added in step (1). After the reaction was complete, 80.3 g of white solid 1,2-diindene was obtained. Yield 71.9%.

NMR data is the same as in Example 1.

Claims (13)

1. a synthetic method for the dialkyl group indene compound of vinyl bridging, comprises the following steps:

(1) under protection of inert gas, alkyl substituents and the lithium alkylide of indenes or indenes react in alkane solvents, the alkane solution of the indenyl lithium salts that obtained indenyl lithium salts or alkyl replace;

(2), under protection of inert gas, in obtained above-mentioned alkane solution, add adjacent dibromoalkane hydrocarbon, stir and form uniform mixing solutions;

(3) under protection of inert gas, at above-mentioned mixed solution and dripping activator, the dialkyl group indene compound of Reactive Synthesis vinyl bridging;

Wherein, R is methyl, normal-butyl or the tertiary butyl; R ¹, R ², R ³, R ⁴be selected from H and C respectively ₁-C ₆alkyl; R ⁵, R ⁶be selected from H and C respectively ₁-C ₄alkyl, and R ⁵and R ⁶carbon atom summation is not more than 4.

2. the synthetic method of the dialkyl group indene compound of vinyl bridging as claimed in claim 1, it is characterized in that, in step (1), the temperature of described reaction is 0-100 DEG C, and the reaction times is 1-8 hour.

3. the synthetic method of the dialkyl group indene compound of vinyl bridging as claimed in claim 2, it is characterized in that, in step (1), the temperature of described reaction is room temperature, reaction 2-4 hour.

4. the synthetic method of the dialkyl group indene compound of vinyl bridging as claimed in claim 1, it is characterized in that, in step (1), described alkane solvents is selected from Skellysolve A, normal hexane, normal heptane, octane and sherwood oil.

5. the synthetic method of the dialkyl group indene compound of vinyl bridging as claimed in claim 1, it is characterized in that, in step (1), the mass ratio of the alkyl substituents of described alkane solvents and indenes or indenes is 5-50:1.

6. the synthetic method of the dialkyl group indene compound of vinyl bridging as claimed in claim 1, it is characterized in that, in step (1), the molar ratio of the alkyl substituents of described lithium alkylide and indenes or indenes is 1-1.5:1.

7. the synthetic method of the dialkyl group indene compound of vinyl bridging as claimed in claim 1, it is characterized in that, in step (2), the mol ratio of the alkyl substituents of described adjacent dibromoalkane hydrocarbon and indenes or indenes is 0.5-0.8:1.

8. the synthetic method of the dialkyl group indene compound of vinyl bridging as claimed in claim 1, it is characterized in that, in step (3), described activator is selected from ether, glycol dimethyl ether, tetrahydrofuran (THF), dimethyl furan, 2,5-dimethyl furan and 2,3-cumarone.

9. the synthetic method of the dialkyl group indene compound of vinyl bridging as claimed in claim 8, is characterized in that, in step (3), the mol ratio of the indenes in described activator and step (1) or the alkyl substituents of indenes is 0.1-1:1.

10. the synthetic method of the dialkyl group indene compound of vinyl bridging as claimed in claim 8, it is characterized in that, in step (3), control the rate of addition of activator, control temperature of reaction is 0-100 DEG C, and activator drips and terminates rear continuation reaction 1-8 hour.

The synthetic method of the dialkyl group indene compound of 11. vinyl bridgings as claimed in claim 1, is characterized in that, further comprising the steps of: reaction terminates to wash product afterwards, steams solvent afterwards, then carries out recrystallization to product, obtain white solid.

The synthetic method of the dialkyl group indene compound of 12. vinyl bridgings as claimed in claim 11, it is characterized in that, the solvent of described recrystallization is the mixing solutions of toluene and ethanol.

The synthetic method of the dialkyl group indene compound of 13. vinyl bridgings as claimed in claim 12, is characterized in that, the volume ratio of described ethanol and toluene is 1-4:1.