Sciencemadness Discussion Board

Desiccating hygroscopic stuff moist with ethanol?

Fyndium - 21-11-2020 at 12:23

I rinsed a solid with ethanol to both crash it out from water, extract it from the RBF to filter it, and to dry it from water. The stuff is hygroscopic and temperature sensitive, so are there any desiccants that adsorb ethanol?

Tsjerk - 21-11-2020 at 12:27

Yes, CaCl2 does.

Fyndium - 21-11-2020 at 12:39

Then it's easy because it's been sitting in CaCl2 desiccator for few hours now, and shall remain so.

If I heat the desiccant later to regenerate it, should there be issues by the absorbed ethanol in form of flammable vapors?

Based on the source, it states following:
Quote:

Calcium chloride forms addition compounds with the alcohols. On evaporating a solution in ethyl alcohol at a low temperature rectangular plates of 2CaCl2β‹…7C2H5OH are deposited. The compounds CaCl2β‹…3C2H5OH and CaCl2β‹…CH3OH have also been separated, as well as a mono- and a di-acetone compound, and compounds with isobutyl and amyl alcohols.


It translates that the adduct/complex is stable at low temperatures. No temperature is stated, though, but should this translate to a fact that the desiccator should be in a low temperature to adduct/complex with the ethanol?

[Edited on 21-11-2020 by Fyndium]

unionised - 22-11-2020 at 10:33

Quote: Originally posted by Fyndium  


If I heat the desiccant later to regenerate it, should there be issues by the absorbed ethanol in form of flammable vapors?


[Edited on 21-11-2020 by Fyndium]

Yes.
Be very careful or, given that CaCl2 is cheap- just don't bother unless you can do it in a still and collect the alcohol.

Fyndium - 22-11-2020 at 10:43

I haven't bothered yet to get a bag of CaCl2 to my home lab, but may reconsider it eventually. It costs .50 a kg here.