Preparation method of tetramethyl biphenyl

Abstract

The invention provides a preparation method of tetramethyl biphenyl, which comprises the following steps: mixing halogenated o-xylene, magnesium metal, iodine, ether and transition metal catalyst, and reacting to obtain the tetramethyl biphenyl, wherein the mol ratio of ether to magnesium metal is (0.5-3):1. Compared with the prior art of synthesizing tetramethyl biphenyl from halogenated o-xylene, the invention has the following advantages: by using the raw material halogenated o-xylene as the solvent, the preparation of the format reagent and the coupling reaction are carried out in the initial raw material, so that the addition of abundant anhydrous solvent as the reaction medium is not needed, thereby lowering the reaction cost and simplifying the production technique; the magnesium metal is directly added into the halogenated o-xylene to obtain the format reagent, so the process is simple and the conditions are mild and controllable; and the raw material, the concentration of which in the reaction system is high, is used as the solvent and participates in the oxidation-reduction process in the coupling reaction, no oxidizer is needed, so the reaction conditions are mild and controllable.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, in particular to a preparation method of tetramethylbiphenyl. Background technique [0002] As a high-performance polymer, polyimide has high temperature resistance, solvent resistance, radiation resistance, good mechanical properties and dielectric properties, and the thermal decomposition temperature of biphenyl polyimide can reach 600 ° C. One of the varieties with the highest thermal stability in the material, it has broad application prospects in the fields of mechanical electronics, aerospace, large motors, turbine bearings, heat-resistant filter materials, etc., but its application is limited due to its high preparation cost. [0003] The key monomer for preparing biphenyl polyimide is biphenyl tetracarboxylic dianhydride, and the synthesis cost of this monomer determines the cost of polyimide to a large extent. Therefore, the pursuit of low-cost polyimide An important way to re...

AI Technical Summary

Problems solved by technology

[0005] The existing synthesis technology of tetramethylbiphenyl mainly uses halogenated o-xylene as raw material for collective name, and halogenated o-xylene is obtained by substituting o-xylene, which increases the reaction cost and reaction process to a certain extent. , and the separation of halogenated o-xylene is difficult, and the industrial cost is relatively high

[0007] The Chinese patent with the application number CN200410089450 and the Chinese patent with the application number CN200780035615 both disclose the coupling of halogenated o-xylene and halogenated o-xylene Grignard reagent under the catalysis of a transition metal compound to obtain tetramethylbiphenyl, However, this method needs to use a large amount of anhydrous tetrahydrofuran as a solvent, which increases the requirements of the operating environment and increases the cost; at the same time, the formation process of the Grignard reagent needs to be realized by using the exchange of commercially available Grignard reagents, which also brings The improvement of operation requirements and the increase of cost; on the other hand, it is also necessary to use dichloroalkanes with high toxicity as oxidant, which will cause violent reaction when added to the reaction system, making the reaction difficult to control

Images