- Novel preparation method of 2, 4, 5-trifluorophenylacetic acid
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The invention discloses a novel preparation method of 2, 4, 5-trifluorophenylacetic acid, which belongs to the technical field of preparation of medical intermediates, and comprises the following preparation steps: carrying out nitration reaction on sulfuric acid and m-dichlorobenzene to obtain an intermediate II; adding the intermediate II, a phase transfer catalyst and potassium fluoride into an aprotic solvent to obtain an intermediate III; performing hydrogenation reaction on the intermediate III to obtain an intermediate IV; carrying out diazotization reaction on the intermediate IV, nitrosyl sulfuric acid and sodium fluoborate to obtain an intermediate V; performing cracking reaction on the intermediate V to obtain an intermediate VI; carrying out reduction reaction on the intermediate VI, and then carrying out bromination reaction on the intermediate VI and liquid bromine to obtain an intermediate VII; subjecting the intermediate VII to a substitution reaction with diethyl malonate, and obtaining 2, 4, 5-trifluorophenylacetic acid after hydrolysis and purification. A novel synthesis route is provided, the problem that technological operation is tedious is solved, the requirements for reaction and operation conditions are low, anhydrous and oxygen-free reaction conditions are not needed, the method is suitable for industrial production, and the yield and purity are greatly improved.
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- PROCESS FOR THE PREPARATION OF 1-BROMO-2,4,5-TRIFLUOROBENZENE
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The present invention relates to a process for the preparation of l-bromo-2,4,5-trifluorobenzene from 2,4,5-trifhioroaniline or sulfate salt thereof. The present invention also relates to a process for the preparation of 1,2,4-trifluorobenzene from 2,4,5-trifluoroaniline and then converting into 1-bromo-2,4,5 -trifluorobenzene.
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Page/Page column 12-13; 17-18
(2021/09/17)
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- Efficient preparation method of 2, 4, 5-trifluorophenylacetic acid
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The invention discloses an efficient preparation method of 2, 4, 5-trifluorophenylacetic acid and belongs to the technical field of synthesis of a pharmaceutical intermediate. The preparation method comprises synthesis of 2, 3, 5-trifluoroaniline, synthesis of 1, 2, 4-trifluorobenzene, synthesis of trifluorobromobenzene and synthesis of a desired product 2, 4, 5-trifluorophenylacetic acid. The preparation method is simple and easy to operate, utilizes cheap and easily available raw materials and has high reaction efficiency and good repeatability.
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Paragraph 0015; 0016; 0017; 0018
(2018/03/26)
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- Preparation method of 1-bromo-2,4,5-trifluorobenzene
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The invention discloses a preparation method of 1-bromo-2,4,5-trifluorobenzene. The preparation method comprises following steps: a, raw material preparation; b, acid reaction; c, bromination reaction; and d, reduction reaction. According to the preparation method, bromination reaction is adjusted, the using amount of bromine is reduced, and a small amount of hydrogen peroxide is adopted instead,so that production cost is reduced; increasing of bromine amount is capable of reducing side product yield, and increasing target product yield.
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Paragraph 0021; 0022
(2018/03/25)
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- PROCESS FOR THE PREPARATION OF ORGANIC BROMIDES
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The present invention provides a process for the preparation of organic bromides, by a radical bromodecarboxylation of carboxylic acids with a bromoisocyanurate.
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Paragraph 00139
(2017/07/28)
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- Method for producing tetrakis ( fluoroaryl) borate-magnesium compound
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Fluoroaryl magnesium halide is reacted with a boron compound so that a molar ratio of the fluoroaryl magnesium halide to the boron compound is not less than 3.0 and not more than 3.7, so as to produce a tetrakis (fluoroaryl) borate·magnesium compound. With this method, there occurs no hydrogen fluoride which corrodes a producing apparatus and requires troublesome waste water treatment.
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