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Synthesis of Bis(cyclopentadienyl)zirconium dichloride

Jun 21，2022

Zirconocene dichloride is the main catalyst of the Kaminsky type catalytic system. This type of catalyst has high activity and isotacticity in catalyzing the high polymerization of olefins, and has also been reported in the literature for catalyzing the oligomerization of olefins. Zirconocene dichloride is also the main component of Negishi's reagent, which can be used for intramolecular diene cyclization and intermolecular alkyne and alkene cyclization.

Synthesis of Bis(cyclopentadienyl)zirconium dichloride

(1) depolymerization cyclopentadiene under nitrogen atmosphere, 40-42 ℃ of cyclopentadiene monomers obtained by distillation are collected in the flask cooled by ice-water bath for subsequent use.

(2) Under the protection of pure nitrogen atmosphere, add 69g of sodium wire cut into small pieces and 450mL of diethylene glycol dimethyl ether into the 1000mL three-necked flask, stir mechanically, slowly heat to 120-160 ° C, until the sodium is completely Melted sodium sand and evenly dispersed in diethylene glycol dimethyl ether, 270mL of freshly prepared cyclopentadiene was added dropwise into a three-necked flask, and after the dropwise addition was completed, the reaction was refluxed and stirred for 4 hours, until the sodium was completely reacted. Cool to room temperature under protection.

(3) 350 g of zirconium tetrachloride are added to the three-necked flask filled with 500 mL of n-hexane, under nitrogen protection, mechanical stirring conditions, the diethylene glycol diethylene glycol of the sodium cyclopentadiene obtained in (2) The methyl ether solution was added dropwise to it, and the reaction at room temperature was completed for 3 hours, the n-hexane was evaporated, and the diethylene glycol dimethyl ether was evaporated to dryness.

(4) solid is transferred in the Soxhlet extractor of 2000mL, with chloroform extraction 8-10 hour, the extract is cooled to room temperature and filtered, the filtrate is concentrated to about 100mL in batches, separate out a large amount of crude product, filter, filter cake with a small amount of Wash with cold chloroform for 2-3 times and vacuum dry to obtain white crystals with a yield of 70-75%. Melting point: 242-245°C. The product has passed the identification of 1H NMR (300MHz, CDCl3) δ: 6.414 (10H, S)] and ICP-MS (Zr: 31.21%).

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