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ChemicalBook CAS DataBase List 4-Bromo-2-fluoroaniline
367-24-8

4-Bromo-2-fluoroaniline synthesis

8synthesis methods

To a stirred solution of 4-bromo-2-fluoro-l -nitrobenzene (10 g, 45.5 mmol) in EtOH (50 mL)AVater (20 mL) was added iron (12.7 g, 230 mmol) and NH4C1 (24.3 g, 455 mmol). The reaction mixture was stirred at 90 °C for 2 h. After 2 h the reaction mixture was filtered over Celite. The filter cake was washed with EtOH (300 mL), and the filtrate was concentrated under reduced pressure. The residue was purified by silica gel chromatography (S1O2, Petroleum ether/EtOAc=10: l to 5: 1) to afford 4-bromo-2-fluoroaniline.
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Yield:367-24-8 85 %Chromat. ,141474-37-5 15 %Chromat.

Reaction Conditions:

with sodium persulfate;copper(ll) sulfate pentahydrate;sodium bromide in water;acetonitrile at 7 - 25; for 24 h;Overall yield = 63 percent; Overall yield = 867 mg; regioselective reaction;

Steps:

4-Bromo-2-nitroaniline (2a); Typical Procedure for Bromination

General procedure: 2-Nitroaniline (1.0 g, 7.24 mmol) was added to a suspension of CuSO4·5H2O (0.452 g, 1.81 mmol, 25 mol%) in a mixture of CH3CN (20mL) and H2O (10 mL) at 25 °C, and the mixture was stirred at 25 °C for15 min. NaBr (1.34 g, 13.0 mmol, 1.8 equiv.) and Na2S2O8 (2.41 g, 10.1mmol, 1.4 equiv.) were then added simultaneously in three portionsat 7 °C over 15 min. After addition was complete, the mixture was furtherstirred at 7 °C for 2 h and at 25 °C for 22 h. Na2S2O3 (572 mg, 3.62 mmol) was added to the mixture. The pH value of the mixture wasthen adjusted to 9.0 by adding 10% aq. NaOH (8 mL). The mixture wasdiluted with H2O (100 mL) and extracted with AcOEt (100 mL). Theorganic phase was separated and subjected to HPLC analysis (X BridgeC18, 5 m, 4.6 × 150 mm, 30 °C, 1 mL min-1, 50-90% CH3CN (0-20min) then 50% (20-40 min), 254 nm) to obtain the assay yield of 2a(1.49 g, 94.9%) and the ratio of 2a/3a (99.9:0.1). Pure samples of 2aand 3a for analysis were obtained by purification of the evaporatedmixture with silica gel column chromatography (n-hexane/AcOEt =15:1).

References:

Takahashi, Yusuke;Seki, Masahiko [Synthesis,2021,vol. 53,# 10,art. no. SS-2021-F0096-OP,p. 1828 - 1832]

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