I am following a reported procedure to synthesize 4-Br pyrazole but after the solvent is removed i end up with orange coloured oily liquid (no mention of such product in the journal). The procedure says sublimation will give pure product. But how to sublime an oily liquid? I am using NBS for bromination with DMF as the solvent. Cannot use CCl4 as the pyrazole is not soluble in it. The organic extraction is done with ethyle acetate, water, brine and Na2SO4.
If it is oily, it is most possible not pure enough to crystallize or you have still DMF present. Have you done TLC control during recation and also from the oil? How many spots do you have?
You can carry out the reaction also in water. See attached file.
If it is oily ,it is possible that some DMF is remained in it, if it ia a pure compound on TLC. Again extract it with etherical solvent and given wash to organic layer with water twice or thrice. Then conc it, it will solidify surely.
Second approach is by adding anti solvent in it which will also solidify it.
Try adding IPA in Hot and then cool reaction mass.
The oilly liquid is because it is mixture. To separate 4-Br pyrazolate from oily liquid , treat oily liquid with n-hexane & stirr well & keep it overnight in freeze. You are likely to get solid. Otherwise You can chromatograph using column using ethyl acetate solvent.
It is posiible to subilmate FROM oily liquid! But You must do this under vacuum. Use Shlenk flask and cooled "finger" (if dont know what is this write to me personally) and vacou about 2-3 Torr and oil bath 70-100 0C
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