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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: eb51111 on July 31, 2019, 01:21:35 PM

Title: Chloroform stabilisation
Post by: eb51111 on July 31, 2019, 01:21:35 PM

I am using rotavap to remove chloroform from samples - but then re-using (to avoid wasting useful solvent - and cost of new CHCl₃) the distilled chloroform for more samples - that are again rotavapped and so on etc etc.

My question, the chloroform is stabilised with around 1% ethanol (I assume to prevent COCl₂) and HCl formation in air - although theoretically the ethanol (should) be rotavapped over at around the same pressure - is there any problem with using the distillate again or is it appreciably more likely to decompose and should I re-add 1% abs. EtOH to ensure stabilisation? I'm not sure the extent that chloroform undergoes this reaction and on what timescale.

Any help greatly appreciated.

Thanks.

Title: Re: Chloroform stabilisation
Post by: Corribus on July 31, 2019, 01:48:57 PM

In grad school we used recycled solvents for things like column chromatography. I think as long as you're not planning on storing the recycled solvent for months, you'd be fine without adding anything to it. 1% ethanol will change the polarity of the solvent, just be aware of that.