Preparation of Titanocene dichloride

Background

Titanocene dichloride is mainly used as a catalyst for olefin copolymerization and homopolymerization. In foreign countries, it has been produced by several units as an olefin homopolymerization catalyst, and as a catalyst for SBS catalytic hydrogenation with a large amount of it, its market demand It is closely related to the market demand for catalytic hydrogenation of SBS to SEBS.

Preparation

1. Anthracene magnesium method

Bannmann, Hasenqimuge, etc. synthesized dicyclopentadiene titanium dichloride, zirconocene dichloride and ferrocene dichloride with anthracene magnesium. The synthesis method is as follows: add magnesium powder, anthracene and tetrahydrofuran solution under nitrogen protection, and add a few drops of methyl iodide. Stir at a certain temperature to obtain a yellow-green liquid. After the end, put it into an ultrasonic oscillator to shake for 4 hours to obtain an activated anthracene-magnesium orange-yellow precipitate. At a temperature of 60° C., cyclopentadiene and titanium tetrachloride solution were added dropwise, cooled to room temperature after 20 min, filtered, and the filter residue was washed with dichloromethane. The washed filtrate and the filtrate were combined and concentrated to an appropriate amount, and crystallized in an ice bath. Obtain red dicyclopentadiene titanium dichloride crystals. The reported yield of this method is about 65%.

2. Metal sodium method

In 1959, Sloan.C.L and others used sodium metal to synthesize dicyclopentadiene titanium dichloride, and investigated the influence of various factors on the reaction. In China, Li Wenyu, Huang Biwu and others have also researched and improved the process of metallic sodium, which reduces the operational complexity and improves the yield. The main process of metal sodium method: nitrogen is introduced into the reaction device, and sodium sand is prepared by using xylene solution. The xylene was removed and dry tetrahydrofuran was added. The pre-cracked cyclopentadiene was added dropwise during stirring in the ice bath. The obtained sodium cyclopentadienyl was added dropwise to the titanium tetrachloride solution. React at a certain temperature for 7h. After the completion of the reaction, the solvent was evaporated to dryness by a rotary evaporator, and the obtained solid was extracted with dichloromethane. The red crystal dichlorodimucin was obtained, and the yield was about 60%.

3. Diethylamine method

Foreign JohnM.Birmmghan and domestic Zhao Lifang, etc. reported the use of diethylamine, titanium tetrachloride, cyclopentadiene to synthesize dicyclopentadiene titanium dichloride. The synthetic method process is as follows: in an ice bath, titanium tetrachloride is slowly added dropwise to the tetrahydrofuran solution. With the addition of titanium tetrachloride, a yellow solid was formed, and the formed solid was slowly dissolved in the tetrahydrofuran solution under stirring. Then dried diethylamine was added, and the color of the solution changed to dark green. Finally, cyclopentadiene was added dropwise to obtain a brown-red solution. Heating, refluxing, keeping cool and filtering to obtain a red solid. The solid was washed with hydrochloric acid, dried, extracted with chloroform, and dried to obtain red dicyclopentadienyl titanium dichloride.

It is reported in the literature that the raw material used in the synthesis of dicyclopentadiene titanium dichloride from diethylamine in a yield of about 73% is cheap, easy to obtain and convenient.