ChemicalBook CAS DataBase List 2,3-Difluorobenzoic acid

2,3-Difluorobenzoic acid synthesis

4synthesis methods

Product Name:2,3-Difluorobenzoic acid
CAS Number:4519-39-5
Molecular formula:C7H4F2O2
Molecular Weight:158.1

124-38-9

126163-64-2

4519-39-5

Carbon dioxide gas was passed into a reaction solution containing lithium 2,3-difluorobenzene (CAS:126163-64-2) at a temperature of -65 to -60 °C, ensuring that the molar ratio of carbon dioxide to lithium 2,3-difluorobenzene was 1.5:1. The reaction was maintained at this temperature for 4 hours. Upon completion of the reaction, water was added for hydrolysis at a mass ratio of water to reaction solution of 1.5:1 and the hydrolysis temperature was controlled at 15-20 °C. Subsequently, the organic solvent was removed by heating distillation and the reaction mixture was concentrated. The temperature was adjusted to 20-22 °C and the reaction mixture was acidified with a 10% hydrochloric acid solution with a molar ratio of hydrochloric acid to lithium 2,3-difluorobenzene of 2:1. After acidification, the reaction was kept for 3 hours. The reaction mixture was cooled to 0°C and the crystals formed were collected by diafiltration. The crystals were washed with a buffer solution of pH=2 and subsequently dried to give 2,3-difluorobenzoic acid. The purity of the final product was 99.5% and the yield was 90%.

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126163-64-2
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4519-39-5
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Yield:4519-39-5 91%

Reaction Conditions:

at -65 - -60; for 6 h;Temperature;

Steps:

6.B (B) Addition reaction:

General procedure: Temperature control -65 ~ -60 ° C,Passing carbon dioxide into the reaction solution containing lithium 2,3-difluorobenzene,The molar ratio of carbon dioxide to metal substitution reagent is 1.5:1,The incubation time was 4 hours.Add water to hydrolyze,The mass ratio of the added water to the reaction liquid containing lithium 2,3-difluorobenzene is 1.5:1.The hydrolysis temperature is 15 to 20 °C.The organic solvent is then separated by heat distillation and concentrated and recovered.The temperature is controlled at 20 to 22 ° C and acidified with 10% hydrochloric acid.The molar ratio of acid to metal-substituted reagent is 2:1.After the addition of the hydrochloric acid solution, the reaction was kept for 3 hours. Cool down to 0 ° C,The crystal obtained by suction filtration was washed with a buffer solution of pH=2.Then wash,Dry to obtain 2,3-difluorobenzoic acid.The product obtained has a purity of 99.5% and a product yield of 90%.

References:

CN108658759,2018,A Location in patent:Paragraph 0032; 0037

124-38-9
724 suppliers
$214.00/14L