Purification and crystallization of the final product (help needed)
So I followed a procedure to brominate (Cu2SO4/NaBr/Na2S2O8) 2-nitroaniline and yield 4-bromo-2-nitroaniline. At the end of the reaction I had 2
layers. Dark yellow organic layer on top and water layer at the bottom.
The paper says to adjust pH to 9 and extract with EtOAc. Which I did. I then distilled off the solvent to a few milliliters and let it cool. Nothing
crystallized, so I put it in the freezer overnight. Nothing. I then evaporated EtOAc completely to give dark brown residue, which looked pretty crude.
So I thought OK, the final product is not soluble in water, what if I could dissolve it in IPA and then add water until the 4-bromo-2-nitroaniline
crashes out. I dissolved 1 g of the product in a few ml of hot IPA and then added water to crash out the product, but instead of precipitation all I
got was a few brown oil drops floating on top.
In the paper authors use column chromatography to purify the final product. Unfortunately I do not have access to that.
What are my options here to purify the final product?
Link to the paper:
DOI: 10.1055/a-1441-3236
"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 (20 mL) and H2O (10
mL) at 25 °C, and the mixture was stirred at 25 °C for 15 min. NaBr (1.34 g, 13.0 mmol, 1.8 equiv.) and Na2S2O8 (2.41 g, 10.1 mmol, 1.4 equiv.) were
then added simultaneously in three portions at 7 °C over 15 min. After addition was complete, the mixture was further stirred 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 was then adjusted to 9.0 by adding 10% aq. NaOH (8
mL). The mixture was diluted with H2O (100 mL) and extracted with AcOEt (100 mL)."
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