ChemicalBook CAS DataBase List 4-FLUORO-2-HYDROXYBENZOIC ACID

4-FLUORO-2-HYDROXYBENZOIC ACID synthesis

15synthesis methods

Product Name:4-FLUORO-2-HYDROXYBENZOIC ACID
CAS Number:345-29-9
Molecular formula:C7H5FO3
Molecular Weight:156.11

1583-58-0

345-29-9

General procedure for the synthesis of 4-fluorosalicylic acid from 2,4-difluorobenzoic acid: dimethylsulfoxide (DMSO, 4 L), 2,4-difluorobenzoic acid (500 g, 3.16 mol) and sodium hydroxide (NaOH, 253 g, 6.32 mol) were added to a dry 10 L four-neck flask. The mixture was heated to 130 °C and reacted for about 8 h, during which the progress of the reaction was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction system was cooled to room temperature. Subsequently, the reaction solution was slowly poured into 40 L of ice water and the pH was adjusted to 2?3 with concentrated hydrochloric acid (care was taken that the temperature did not exceed 20 °C during the adjustment). At this time, a large amount of solid precipitated, continue to stir for 2 hours and then pump-filtered. The filter cake was washed with appropriate amount of water to obtain a white solid. The resulting solid was dried under reduced pressure at 60°C for 12 h. 450 g of 4-fluorosalicylic acid was finally obtained with a yield of 90% and a melting point of 184.9-185.2°C. The solid was dried at 60°C for 12 h under reduced pressure.

1583-58-0 Synthesis

1583-58-0
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$6.00/5g

345-29-9
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$10.00/1g

Yield:345-29-9 90%

Reaction Conditions:

with sodium hydroxide in dimethyl sulfoxide at 130; for 8 h;

Steps:

1.1 First step: Preparation of 4-fluorosalicylic acid

Dimethyl sulfoxide (DMSO, 4 L) was added to a dry 10 L four-necked flask,2,4-Difluorobenzoic acid (500 g, 3.16 mol)And NaOH (253 g, 6.32 mol),And warmed to 130 , the reaction for about 8h,TLC detection,Until the reaction is complete, the reaction system was reduced to room temperature,The reaction solution was slowly poured into 40L ice water,With concentrated hydrochloric acid to adjust the pH to 2 ~ 3 (adjust the temperature of the process is not higher than 20 )A large number of solid precipitation, continue stirring 2h suction filtration, the filter cake was washed with an appropriate amount of water,Obtained as a white solid, dried at 60 ° C for 12h under reduced pressure to give 4-fluorosalicylic acid 450g, yield 90%.mp 184.9 ~ 185.2 ° C.

References:

CN107501260,2017,A Location in patent:Paragraph 0030; 0031; 0033; 0034

456-22-4 Synthesis