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Assuming I have an organic substance that is known to be "soluble in alcohol" (e.g. capsaicin) I want to extract, which alcohol should/can I use? I know that both ethanol and methanol are commonly used, but what about:

  • isopropanol
  • glycerol
  • n-Butanol
  • 1,4-Butanediol
  • tert-Butyl alcohol
  • 1-Pentanol
  • tert-Amyl alcohol

In general, which alcohols are suitable/unsuitable for organic compound extraction (e.g. which should be the best solvent in terms of amount of solute dissolved in given volume of solvent), and why? Is there any a priori way to determine e.g. if isopropanol extraction will be OK for a given "soluble in alcohol" organic substance?


Note: I am aware of this discussion, but it doesn't cover the specific nature of alcohol extraction.

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    $\begingroup$ Need to consider how you're going to isolate the extract once you've done the extraction. Some of your possible solvents have high boiling points and will not be easy to remove. $\endgroup$ – Waylander Jan 30 '18 at 13:04
  • $\begingroup$ @Waylander going up to 300C is OK with me; most of them are boiling @ <150C, one way or the other. $\endgroup$ – vaxquis Jan 30 '18 at 15:32
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    $\begingroup$ 'Soluble in alcohol' probably just means soluble in ethanol. Of course it may well be soluble in other alcohols as well. $\endgroup$ – bon Jan 30 '18 at 17:56
  • $\begingroup$ What are the foreseen uses of the extraxted? How many solvents are available to you? How do you suppose to recover the extracted? Once one know details as these, then one might can easily answer. Cost and toxicity can matrer. And so on. You mention that you can heat up to 300 °C , but capsaicin does not care of that as it melts at 62°. And so on. $\endgroup$ – Alchimista Jan 30 '18 at 20:14
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The optimal solvent will extract the greatest amount of desired product and the least amount of difficult-to-remove substances.

The extraction is only the first step; separation from solvent and other extractives follows. Try one, then another solvent to see if there is a difference. Maybe number of carbons or hydroxyls is important; you can also mix alcohols, and/or add water.

Capsaicin has a phenolic group; perhaps it would be extracted from its source with alkali (NaHCO3 or Na2CO3). enter image description here

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