- Preparation method of 3,5-dichloro-4-fluorobromobenzene compound
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The invention relates to a preparation method of 3,5-dichloro-4-fluorobromobenzene. According to the preparation method, 2-fluoro-3-chloronitrobenzene is used as a starting raw material and subjectedto bromination, reduction and diazochlorination to synthesize 3,5-dichloro-4-fluorobromobenzene. The whole synthesis route of the method has the advantages of accessible raw materials, mild reaction conditions, environment friendliness, low equipment requirements and high product purity and yield.
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Paragraph 0047-0052
(2020/12/14)
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- Preparation method of 3, 5-dichloro-4-fluorobromobenzene compound
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The invention relates to a preparation method of 3, 5-dichloro-4-fluorobromobenzene. The method takes 2, 6-dichlorofluorobenzene as a raw material, the raw material is simple and easy to obtain, the cost is low, the method is simple in process, mild in condition and environment-friendly, the separation and purification of an intermediate product 2, 4-dichloro-3-fluoronitrobenzene through a crystallization method are much more efficient than those of the traditional distillation means, and the process safety is high. The loss is lower.
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- Preparation method of 3,5-dichloro-4-fluorobromobenzene compound
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The invention relates to a preparation method of 3,5-dichloro-4-fluorobromobenzene, which comprises the steps of (1) reacting 2,4-dichloro-3-fluoroaniline with sulfuric acid in the presence of water and glacial acetic acid to obtain 2,4-dichloro-3-fluoroaniline sulfate; (2) adding bromine into the product mixture obtained in the step (1), then dropwise adding hydrogen peroxide, and reacting to obtain 2,4-dichloro-3-fluoro-6-bromoaniline sulfate; and (3) adding sodium hypophosphite and a catalyst copper salt into the product mixture obtained in the step (2), then dropwise adding sodium nitrite,and reacting to obtain 3,5-dichloro-4-fluorobromobenzene. The method is simple in process, low in cost, mild in condition, high in process safety and capable of effectively reducing the use amount ofbromine.
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- PROCESS FOR THE PREPARATION OF HALO-SUBSTITUTED BENZENES
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The invention relates to a process for the preparation of compound of formula (I) wherein R1 is halogen and R2 is halogen or hydrogen; comprising a) reacting the compound of formula (II) in an aprotic organic solvent in the presence of an aprotic polar co-solvent with a magnesium amide base followed by a halogenating agent, to the compound of formula I wherein R1 is halogen and R2 is hydrogen, and b) reacting the compound of formula (I), wherein R1 is chloro and R2 is hydrogen, in an aprotic organic solvent in the presence of an aprotic polar co-solvent with a magnesium amide base followed by a halogenating agent to a compound of formula I, wherein R1 is chloro and R2 is halogen.
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Page/Page column 7; 8
(2016/12/26)
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