4487-61-0Relevant articles and documents
Preparation method of 3,4,5,6-tetrafluorosalicylic acid
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Paragraph 0018; 0028; 0030, (2017/08/31)
The invention discloses a preparation method of 3,4,5,6-tetrafluorosalicylic acid. The preparation method comprises the following steps of adopting 2,3,4,5,6-pentafluorobenzoyl chloride as a raw material, obtaining intermediate products by condensation of the raw material with ethyl acetoacetate and complexation of the condensation products with cupric ions, and acidifying the intermediate products; obtaining 5,6,7,8-tetrafluoro-2-methyl-4-oxo-4H-benzopyran-3-carboxylic ethyl ester by cyclizaiton of the acidified products through heating, stirring the cyclization products in a sodium hydroxide solution, dropwise and slowly adding excessive amount of hydrogen peroxide solution, stirring and preserving the temperature of the mixture, and completing the reaction after the cyclization products are not detected by TLC; removing excessive amount of hydrogen peroxide by adding sodium thiosulfate, increasing the temperature for 1 hour, adjusting pH by adding hydrochloric acid after cooling the mixture to room temperature, and extracting target products with methyl tertiary butyl ether; drying the target products with anhydrous sodium sulfate, distilling the filter liquid, and obtaining 3,4,5,6-tetrafluorosalicylic acid by recrystallization of crude products by using dichloromethane. The preparation method has the advantages of low requirement for equipment, no pollution due to by-products of water, product recovery of 78-83% and crude product purity of 97%.
A route to ethyl α-pentafluorobenzoyl-β-oxobutanoate via its copper(II) chelate
Burgart,Kisil,Saloutin,Chupakhin
, p. 76 - 76 (2007/10/03)
Ethyl 2-pentafluorobenzoyl-3-oxobutanoate has been prepared by the acylation of ethyl acetoacetate with pentafluorobenzoyl chloride via a copper(II) chelate.
