Sciencemadness Discussion Board

DCM

Housane - 22-1-2020 at 13:44

Hi I am wondering if ethyl acetate could be used as a direct DCM replacement as DCM becomes increasingly hard to find for extractions like caffeine from tea.

Housane

DavidJR - 22-1-2020 at 13:51

This is too vague to answer. It will probably be suitable for some uses but not for others. So no, it is not a "direct replacement", but for extracting caffeine from tea, it might well work.

Housane - 22-1-2020 at 14:03

Ok, for extractions like caffeine and others with a DCM solvent would normally be possible with ethyl acetate

Steam - 22-1-2020 at 18:27

One of the main issues with EtAc is that it can degrade into ethanol and acetic acid under certain conditions. As long as you avoid those conditions and trace amounts of ethanol and Ac acid are not detrimental then you should be good to go. If you think DCM is hard to find, try getting a hold of carbon tetrachloride via OTC sources.... :d

Housane - 22-1-2020 at 23:05

Quote: Originally posted by Steam  
One of the main issues with EtAc is that it can degrade into ethanol and acetic acid under certain conditions. As long as you avoid those conditions and trace amounts of ethanol and Ac acid are not detrimental then you should be good to go.


What conditions do I need to avoid is it alklinity, acidity or heat

Tsjerk - 23-1-2020 at 03:01

Quote: Originally posted by Housane  


What conditions do I need to avoid is it alklinity, acidity or heat



Acid in combination with water and alklinity in general. Heat is no problem in normal extractions, the solvent just boils off.

Just realize ethyl acetate dissolves a lot of water (3%) that has to be taken care of before you evaporate it to isolate your product. Also ethyl acetate is pretty soluble in water (8%).

Always make sure you use saturated NaCl instead of plain water when working with ethyl acetate.

Housane - 23-1-2020 at 12:27

Quote: Originally posted by Tsjerk  
Quote: Originally posted by Housane  


What conditions do I need to avoid is it alklinity, acidity or heat



Acid in combination with water and alklinity in general. Heat is no problem in normal extractions, the solvent just boils off.

Just realize ethyl acetate dissolves a lot of water (3%) that has to be taken care of before you evaporate it to isolate your product. Also ethyl acetate is pretty soluble in water (8%).

Always make sure you use saturated NaCl instead of plain water when working with ethyl acetate.



Thanks that is very helpful

happyfooddance - 23-1-2020 at 15:29

Ethyl acetate is used to decaffeinate coffee industrially, so yes.

However, caffeine is much more soluble in DCM and chloroform, so these will be much better for caffeine extraction in the lab.

Chloroform can be easily made from acetone and bleach, or isopropanol and bleach, via haloform reaction.

Texium - 23-1-2020 at 20:25

For extractions, ethyl acetate is generally a suitable replacement (as long as significant acidity or alkalinity are avoided, as noted by previous posters). The only other issue with it in that application is that since it's less dense than water, performing multiple extractions is a bit more cumbersome than it is with DCM.

Things get more complicated if you want to make the swap for use in chromatography. For normal phase chromatography, ethyl acetate is a much more potent eluent than DCM. In my experience, eluting a compound with 1% of ethyl acetate in hexanes or petroleum ether will give similar results to eluting with 10% DCM in hexanes or petroleum ether. Therefore, if you were following a procedure where DCM/hexanes is used for a column, you would want to reduce the percentage tenfold to use ethyl acetate in its place, and it may not go as smoothly if it's super non-polar compounds that you're trying to separate.