Perfluorooctanoic acid fluoride preparation method

Abstract

The invention relates to a perfluorooctanoic acid fluoride preparation method. According to the invention, fluorine gas is diluted by inert gas and is subjected to caprylyl chloride under low temperature condition to prepare perfluorooctanoic acid fluoride. The technical means such as inert gas dilution, reaction temperature reduction, stirring or filling material increasing can be carried out so that the reaction of fluorine gas and caprylyl chloride is milder and more uniform, control is easy, yield of perfluorooctanoic acid fluoride is greatly increased, usage of an electrolytic tank metal anode is avoided, and the generation of a solid waste material is basically eliminated. Direct reaction of fluorine gas and caprylyl chloride can avoid the energy waste, increases perfluorooctanoic acid fluoride yield, reduces the generation of by products such as low fluorine carbon due to a scission reaction of long-chain carbon atoms, quality of the perfluorooctanoic acid fluoride product is guaranteed, and the method has great meaning for perfluorocapylic acid production enterprises.

Description

technical field [0001] The invention relates to a preparation method of perfluorooctanoyl fluoride, which belongs to the field of organic fluorine chemistry. Background technique [0002] Perfluorooctanoyl fluoride is the key raw material for the preparation of perfluorooctanoic acid. However, due to the high activity of fluorine gas, if fluorine gas is directly used to react with octanoyl chloride, octanoyl chloride will be burned to generate impurities such as CF4, HF, and HCl. The current general preparation method of perfluorooctanoyl fluoride is to quantitatively add anhydrous hydrogen fluoride and octanoyl chloride into the low-temperature electrolytic cell according to the ratio, and then pass through direct current to electrolyze anhydrous hydrogen fluoride to generate fluorine free radicals (or fluorine gas. ), the fluorine radical (or fluorine gas) then undergoes a substitution reaction with octanoyl chloride to generate perfluorooctanoyl fluoride. [0003] Howev...

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Problems solved by technology

[0003] However, the low-temperature electrolysis method uses fixed electrodes with small spacing, and there is no diaphragm between the cathode and anode electrodes. In the electrolysis reaction, the newly generated hydrogen and fluorine radicals (fluorine gas) on the cathode and anode electrodes are easily reversed to regenerate hydrogen fluoride, resulting in A great waste of energy; and affected by the structure of the electrolytic cell, the flow performance of the electrolyte in the electrolytic cell is extremely poor, resulting in a serious excess of fluorine free radicals (fluorine gas) around the anode plate, and the activity of fluorine free radicals (fluorine gas) Very high, it is very easy to cause chain scission reaction of long-chain carbon atoms and generate by-products. Due to the influence of the above reasons, the yield of perfluorooctanoyl fluoride prepared by low-temperature electrolysis is extremely low, generally only about 10%.

Because the impurity content of the perfluorooctanoyl fluoride product prepared by this method is relatively high, it greatly affects the quality of its follow-up perfluorooctanoyl fluoride product; in addition, the metal anode (nickel, iron, etc. ) During the electrolysis process, it is very easy to lose electrons to form metal anodes. These metal cations further contact with fluorine free radicals and hydrogen fluoride to form insoluble metal fluorides that are deposited in the electrolyte, further causing waste of energy and materials, and producing difficult Treatment of solid-liquid mixed waste