What is a best way to purify a viscous liquid organic product other than column chromatography?
Solve it in a usable solvent or proof another separation method - may be sorption on silicagel ....
Adsorbtion to silica then dry load to dry column, then proceed with addition of mobile phase. If I have 1 g of neat crude goo, then I add 1 g of silica and some solvent, concentrate on rotavap and high vacuum until it becomes a free flowing powder. If you cannot get it to freely flow, add more silica until it does.
If you can acidify or basify to make a salt, you can crystallize that, then react the salt with an acid or base to form the free species.
Vacuum distillation might work. As may sublimation onto a coldfinger with dry ice (the product will need to be a solid at dry ice temp) if the species has the right properties.
It really depends on the stability/functional groups on the species.
It depends on the impurities that you are trying to remove from your viscous oil and the properties of your compound and impurities.
Forming a salt or other derivative and then crystallising is a good idea if you have the right functionality, as is vacuum distillation/sublimation if your compound is thermally stable enough and ideally the most volatile component.
If you have a particularly greasy non-polar compound you can dissolve it in acetonitrile and serially extract with hexane. Dissolving in a solvent and trying to wash out your impurities is also worth considering, depending on what you expect those impurities are. If your product is mostly clean and contains minor impurities or is a bit off colour then you can also dissolve it in a solvent and pass it over activated charcoal.
if your compound is polar you can triturate with non polar solvent and decant to remove non polar impurities.
A quick-and-dirty way to remove impurities that are very different in polarity is to adsorb the material onto a short column of silica gel (use Brennan's trick if need be), and elute stepwise with increasingly polar solvents (e.g., hexane, then DCM, then EtOAc.) This is much faster than an actual chromatography, and uses only a fraction of the silica gel (about 20 g/g of product.)
Why you are not interested in Column?
What's about TLC. Did u try? Is there any solubility problem?
Thank you Mr. Ghosh. I have used column chromatography. As it takes lot of time, i wanted to try another method.
Try to develop a solvent system in which the product of interest appears far from another spot in TLC...If you are able to do this then you can scratch that spot from TLC, redissolve in solvent and use further ..i think in one day, you will get sufficient amount of product required for structural elucidation...This is very less time consuming than column chromatography..
Good luck
In addition to the possibility of using preparative TLC, you can as well try solvent extraction where the compound of interest has higher distribution in a particular solvent. If this is to be used in place of preparative TLC, you must take into cognizance the polarity of the solvent and as well that of your compound as this is a major key to using solvent extraction.
Yaa.. if u want to avoid Column..As I have told in last mail, go for TLC.
Its easy and effective. Depending on the compound's nature u can select Alumina or Silica column. remember, Silica surface is highly active than Alumina.
Hope, it will help.
Good Luck,
Thanks,
PG
You can try 50g sample filtration on sintered glass funnel (5-inch height and 5-inch dia) by loading approximately 10 times silica gel (used for column chromatography) and packing with hexane. You can finish approximately in 3-4 hours by slowly increasing polarity with 1% ethyl acetate. Don't use vacuum for filtration.
After extraction with suitable solvent,,remove volatile solvent by rota eveporator and finally by vaccum distillation you can collect pure viscose organic liquid by bulb bulb method. I myself have tried ans worked successfully.You can try it.
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