Synthesis method of p-trifluoromethyl benzonitrile compound

Abstract

The invention relates to a preparation method of a p-trifluoromethyl benzonitrile compound. The structural formula of the p-trifluoromethyl benzonitrile compound is shown as formula (I), wherein X isa group selected from nitro or halogen. The p-trifluoromethyl benzonitrile compound is prepared by reacting a compound shown as formula (II) with cuprous cyanide under the action of sodium bromide or / and potassium bromide. The method provided by the invention adopts a low-cost catalyst, has a reaction conversion rate and selectivity up to 95% or more, also makes inorganic salts and tar easy to separate in the subsequent treatment process, thereby simplifying the post-treatment process and reducing the discharge of three wastes, and the method is suitable for large-scale industrial production.

Description

technical field [0001] The invention relates to the field of pesticide chemistry, in particular to a preparation process of p-trifluoromethylbenzonitrile compounds. Background technique [0002] Isoxaflutole (isoxaflutole) is an inhibitor of hydroxyphenylpyruvate dioxygenase, which belongs to the class of benzoylisoxazole herbicides. Synthesis, resulting in the accumulation of tyrosine, which hinders the biosynthesis of plastoquinone and tocopherol, thereby affecting the biosynthesis of carotenoids. [0003] 2-nitro-4-trifluoromethylbenzonitrile is an important intermediate in the synthesis of isoxaflumazone. There are many ways to synthesize 2-nitro-4-trifluoromethylbenzonitrile. Disclosed in patent document 1 adopts the method for synthesizing 2-nitro-4-trifluoromethylbenzonitrile using 3-nitro-4-fluorobenzonitrile as raw material, adopts sodium cyanide or potassium cyanide as in the reaction process Cyanide reagents do not use catalysts, but the reaction has only achie...

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Problems solved by technology

But the reaction selectivity is only 90%, the conversion rate is only 77%, and because of the use of highly corrosive bromine, it is not suitable for industrial production

[0006] Patent Document 4 discloses the preparation of 2-nitro-4-trifluoromethylbenzonitrile by reacting 3-nitro-4-chlorobenzonitrile with cyanide in the presence of bromide and tetraphenylphosphine bromide However, due to the use of expensive tetraphenylphosphine bromide and bromide as catalysts, the cost of industrialization is still high

CN105175282A discloses the synthetic method that uses catalyst I and catalyst II and methylimidazole ionic liquid to jointly catalyze 2-nitro-4-trifluoromethylbenzonitrile by cuprous bromide, nickel bromide, but due to adopting ionic liquid As a reagent, the cost is relatively high, and it is not easy to industrialize

But the reaction time is longer and the production efficiency is lower

[0009] In summary, the method for synthesizing 2-nitro-4-trifluoromethylbenzonitrile or 2-chloro-4-trifluoromethylbenzonitrile in patent documents 1 to 6 has low production efficiency, and the conversion rate, yield or selectivity is not high or expensive

And for the catalyst used in the reaction, on the one hand, copper bromide, nickel bromide and other bromides are expensive, the production cost is high, and it is difficult to market, on the other hand, lithium bromide has a very strong water absorption capacity, and it is very easy to absorb water when placed at room temperature. Difficult, prone to various side effects

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