[soma_seeker]

Hi everyone,  this is my first post here on your forums.  Thanks in advance for your time.

Ok, so I'm performing a hydrothermal liquefaction of lignocellulosic material in an aqueous (basic) solvent system.  After performing the reaction I am left with an aqueous mixture of;
-  Solid starting material/char
-  Base-soluble breakdown products and starting material
-  Organic solvent soluble breakdown products and starting material

I then wish to perform an extraction with diethyl ether (from previous work performed by others both within my lab and elsewhere, diethyl ether and dichloromethane are the only solvents capable of extracting a sufficient range of breakdown products).  I've found that this forms a fairly stubborn emulsion and is further complicated by the presence of solid material (filtering the solids prior to extraction is not a convenient option).

Ultimately I've devised a workup process that is extremely convenient but involves the centrifuging of diethyl ether, which I'm concerned will not pass the OH&S requirements of the lab.  Dichloromethane is obviously safer, however being denser than water the workup procedure then becomes SIGNIFICANTLY less convenient that with diethyl ether.

My question is, is centrifuging 50 mL screw-cap glass centrifuge tubes containing approximately 20 mL of aqueous solution and the same volume of diethyl ether a significant explosion risk/safety concern?  Does the fact that the diethyl ether is water-saturated significantly reduce the risks involved? 

If the safety risk is in fact too high, can you suggest any ways in which I could reduce the risks involved without changing solvent?  The workup process is so ideal as is that I have even considered looking into a hand-operated bench-top centrifuge (although so far I've only found such instruments that can handle 15mL sample vials).

Thanks very much for any assistance you can offer.

[discodermolide]

Try tert-butylmethyl ether. It's not so volatile as diethyl ether. And in my hands less emulsion formation.

[soma_seeker]

Thanks very much for the reply.

I had actually considered using both methyl tert-butyl ether and hexane.  I'd expected that the extractive potential of hexane would likely be insufficient but that methyl t-butyl ether might suffice.  Unfortunately a colleague more experienced in the area is convinced that diethyl ether and dichloromethane are my only solvent options.

Would you expect diethyl ether to be significantly more effective than methyl t-butyl ether at extracting small organic compounds (predominantly phenolics) and aromatic oligomers?

[discodermolide]

There are lots of solvent options you can choose. Hexane and acetonitrile are not miscible, for example.
You could try dichloromethane lone or the ether alone. The variations are countless.
T-Butylmethyl ether is not as soluble in water.
Anyway we are experimental scientists, discussion is good experiment is better.

[soma_seeker]

Thanks again.

What I meant by my only option, is that apparently diethyl ether and DCM are the only common solvents that will extract the range of products that I need to from the aqueous phase.
I don't want to use DCM as it is denser than water, which will significantly influence the practical approach of the workup I've devised.

What I was really hoping to determine is whether the diethyl ether has a significantly lower explosion risk when saturated with water.  Alternatively, anything else I could do to lower the risks associated with centrifuging diethyl ether. 

Perhaps I'm being too optimistic in thinking that this is achievable....

Thank you for your advice!