Synthetic method of fluorine-containing aromatic compounds

Abstract

The invention relates to a synthetic method of fluorine-containing aromatic compounds. The method comprises the following steps: adding aromatic compounds to a fluorination reagent in a refrigerating low-temperature closed reactor in a dropwise manner, stirring and mixing to form a fluorine salt solution, adding a diazotization reagent to the above synthesized fluorine salt solution, and standing and layering the obtained solution; and transferring a lower layer diazo liquid obtained after standing and layering to a low temperature container, heating an upper layer organic phase to a diazo salt decomposition temperature, adding the diazo liquid in the low temperature container to the heated organic phase, and carrying out a decomposition reaction to obtain a decomposed organic layer organic phase which is the corresponding fluorine-containing aromatic compounds. Use of solvents in the reaction reduces side reactions and the generation amount of tar in the reaction process and reduces the loss of hydrogen fluoride; and dropwise addition of the decomposed diazo salt is carried out, so the decomposition heat release amount is easily controlled, the operation safety is improved, the decomposition temperature is constant, the decomposition time is greatly shortened, the decomposition speed is controller, and the method is suitable for industrial production.

Description

technical field [0001] The invention relates to the synthesis of fluorine-containing aromatic compounds, and more specifically relates to a synthesis method of fluorine-containing aromatic compounds. Background technique [0002] Fluorine-containing compounds are currently one of the fastest growing fine chemicals, widely used in materials, pesticides, medicine and other fields, with broad development prospects and strong vitality. In particular, the development and application of the synthesis method of aromatic fluorine-containing compounds has attracted extensive attention from the industrial and scientific circles at home and abroad. With the development of the fluorine industry, the application of organic fluorine intermediates is becoming more and more extensive, and the demand for organic fluorine intermediates in the fields of medicine, pesticides, dyes, fluorocarbon surfactants and fluoroplastics industry is increasing day by day. [0003] Fluorine is abundant in n...

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Problems solved by technology

[0006] For this reason, the earlier industrial production method of fluorine substitution on the aromatic ring to synthesize fluorine-containing compounds is used. Due to the use of fluoroboric acid, the cost of raw materials is high, and a large amount of toxic gas BF is produced during thermal decomposition of fluoroboric acid diazonium salt. 3 , industrial production is limited

At the same time, due to some characteristics of the reaction itself, the application of this method has many limitations: ① When the aromatic ring has hydroxyl, carboxyl, sulfonic acid groups and other groups, the aryl diazonium fluoroborate is soluble in water and cannot form Precipitation; ②If there is a nitro group connected to the aromatic ring, the arylfluoroborate diazonium salt will be rapidly decomposed to produce a large amount of tar, and the decomposition reaction speed is too fast; ③For some diazonium salts that need to be decomposed at a higher temperature , if the aromatic ring is unstable, it will also cause the decomposition of the aromatic ring

[0008] At present, the synthesis of fluorobenzenes from anhydrous hydrogen fluoride in China is generally decomposed by the one-pot method of diazonium salt, and the decomposition rate is controlled by slow temperature rise. The thermal decomposition time is as long as 30-40 hours; and no solvent is used in the synthesis process, and many by-products are formed. The amount of tar is large, and the yield is less than 70%

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