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ChemicalBook CAS DataBase List 4-Bromo-2,6-difluorobenzoic acid
183065-68-1

4-Bromo-2,6-difluorobenzoic acid synthesis

10synthesis methods
 4-Bromo-2,6-difluorobenzoic acid can be used as an organic intermediate mainly used in laboratory research and development processes. Its synthesis method is as followed: To a solution of 1-bromo-3,5-difluorobenzene in THF, was added lithium diisopropylamideat -78°C. The resulting reaction mixture was stirred at an ambient temperature for about 1.5 hours. A cooled reaction mixture was poured onto dry ice and left for about 20 minutes, followed by mixing with aqueous hydrochloric acid (6N). The mixtrue was puritied to get 4-bromo-2,6-difluorobenzoic acid.
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Yield:183065-68-1 84%

Reaction Conditions:

Stage #1: 3,5-difluorobromobenzenewith n-butyllithium;diisopropylamine in tetrahydrofuran;hexane at -78; for 1.75 h;
Stage #2: carbon dioxide at 20; for 16 h;

Steps:

69.A Step A: 4-bromo-2,6-difluoro-benzoic acid

70 mL of THF was cooled to -78°C, and diisopropylamine (4 mL, 28.5 mmol) and butyllithium (13 mL, 27.2mmol, 2.1 M hexane solution) were sequentially added thereto. The mixture was stirred at -78°C for 1 hour, and 1-bromo-3,5-difluorobenzene (5.0 g, 25.9 mmol) dissolved in 15 mL was slowly added thereto. The mixture was stirred at -78°Cfor 45 minutes, and the reaction solution was transferred to a beaker containing solid carbon dioxide and stirred at roomtemperature for 16 hours. The reaction solution was adjusted to pH 3 by the addition of 1N HCl aqueous solution andextracted with EtOAc. The organic layer was collected and dried with MgSO4 to obtain the title compound (5.15 g, 84 %).1H-NMR (CDCl3) δ 7.20 (2H, m)

References:

EP3239143,2017,A2 Location in patent:Paragraph 0181

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