Preparation method for 2-nitro-4-trifluoromethyl cyanobenzene

Abstract

The invention provides a preparation method for 2-nitro-4-trifluoromethyl cyanobenzene. Under the catalysis of a metal catalyst, heating 3-nitro-4-halogen benzotrifluoride shown in the structural formula (2) and an organic cyanogen source in a solvent for reaction to obtain the 2-nitro-4-trifluoromethyl cyanobenzene shown in the structural formula (1), and the structural formula (2) and the structural formula (1) of 3-nitro-4-halogen benzotrifluoride and 2-nitro-4-trifluoromethyl cyanobenzene refer to the Specification. According to the invention, cheap copper salt or cuprous salt is used as the catalyst, and the method has the advantages of high conversion rate, relative low toxicity of a cyanation reagent, the capability of reaction under the atmosphere, and the like.

Description

technical field [0001] The invention relates to a preparation of benzonitrile compounds, in particular to a preparation method of 2-nitro-4-trifluoromethyl benzonitrile. Background technique [0002] 2-nitro-4-trifluoromethylbenzonitrile is a yellow crystal, which is a key intermediate in the synthesis of isoxazole herbicides. As reported in patent EP1000929, it provides a method using 3-nitro-4 - Fluorobenzotrifluoride is used as raw material, and potassium cyanide or sodium cyanide is used as cyanation reagent. Although no metal catalyst is needed in the reaction, the yield of reaction is low, and the sodium cyanide and potassium cyanide toxicity used are very high. Larger, more dangerous. [0003] The patent US4886936 uses cuprous cyanide as the cyanide source and 3-nitro-4-bromobenzonitrile as the raw material to obtain 2-nitro-4-trifluoromethylbenzonitrile with high conversion rate and selectivity . However, cuprous cyanide is a metal cyanide, which is highly toxic a...

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Problems solved by technology

[0002] 2-nitro-4-trifluoromethylbenzonitrile is a yellow crystal, which is a key intermediate in the synthesis of isoxazole herbicides. As reported in patent EP1000929, it provides a method using 3-nitro-4 - Fluorobenzotrifluoride is used as raw material, and potassium cyanide or sodium cyanide is used as cyanation reagent. Although no metal catalyst is needed in the reaction, the yield of reaction is low, and the sodium cyanide and potassium cyanide toxicity used are very high. big, dangerous

However, cuprous cyanide is a metal cyanide, which is highly toxic and has low solubility in organic media, and the amount used is greater than or equal to equimolar amounts, so it is not suitable for large-scale industrial production

Patent CN101585783 improved the method of patent US4886936, adding a small amount of nickel bromide as an auxiliary catalyst, not only 3-nitro-4-bromobenzotrifluoride can be used as raw material, but also 3-nitro-4-chlorotrifluoro Toluene can also be used as a raw material, but the conversion rate is not high, and nickel bromide is not cheap

[0004] In addition, the patent CN102675151 reported using potassium ferrocyanide as a cyanation reagent and using a mixed copper salt as a catalyst. Although the highest conversion rate of 95% and a selectivity of 91% were used to obtain the product, potassium ferrocyanide in the solvent The solubility in the medium is not good, which is not conducive to industrial production

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