December 08, 2019, 01:52:47 PM
Forum Rules: Read This Before Posting


Topic: Silica gel chromatography for less soluble compounds  (Read 1178 times)

0 Members and 5 Guests are viewing this topic.

Offline Babcock_Hall

  • Chemist
  • Sr. Member
  • *
  • Posts: 3906
  • Mole Snacks: +244/-16
Re: Silica gel chromatography for less soluble compounds
« Reply #15 on: October 29, 2019, 02:43:28 PM »
We attempted a column on a similar compound this week.  It dissolved easily into DCM, but when we began to develop the column in 50:50 ethyl acetate/hexanes, the material became crystalline and started to poke up through the sand layer at the top of the column.  Because of the possibility of streaking due to insolubility, we decided to switch to 100% ethyl acetate and accept that the separation would not be as good as one could imagine.  Again, we saw crystals in the fractions with the greatest amount of materials.  I am contemplating the synthesis of a third compound that would be similar to the other two.  Either we would either try to recrystallize it, or we will use a different solvent system entirely, probably one based on DCM or chloroform.

Offline wildfyr

  • Global Moderator
  • Sr. Member
  • ***
  • Posts: 1375
  • Mole Snacks: +149/-9
Re: Silica gel chromatography for less soluble compounds
« Reply #16 on: October 30, 2019, 02:08:38 PM »
If this material has such sparing solubility in ethyl acetate, are you sure you can't recrystallize it? Perhaps in hot hexane/EtOAc even!

I think a DCM/Methanol column would be the right choice if you want to stick to coumns. Something like 95/5 %.


Offline kamiyu2550

  • Regular Member
  • ***
  • Posts: 81
  • Mole Snacks: +2/-2
Re: Silica gel chromatography for less soluble compounds
« Reply #17 on: October 30, 2019, 02:17:33 PM »
We attempted a column on a similar compound this week.  It dissolved easily into DCM, but when we began to develop the column in 50:50 ethyl acetate/hexanes, the material became crystalline and started to poke up through the sand layer at the top of the column.  Because of the possibility of streaking due to insolubility, we decided to switch to 100% ethyl acetate and accept that the separation would not be as good as one could imagine.  Again, we saw crystals in the fractions with the greatest amount of materials.  I am contemplating the synthesis of a third compound that would be similar to the other two.  Either we would either try to recrystallize it, or we will use a different solvent system entirely, probably one based on DCM or chloroform.

EA:hexane = 1:1 may be close to DCM:hexane 2 or 3:1 in terms of polarity. You may try these for the column

Sponsored Links