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I'm doing some metal-organic framework synthesis and most of the syntheses employ DEF or DMF. I'm not a fan of either solvent (okay - I'm a solid state chemist) and would like to use something a bit "greener". Does anyone have suggestions for resources that talk about green solvents for inorganic system, particularly resources that suggest specific replacements for solvents?
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I know it's silly to answer my own post, but I remembered that I attended a seminar given by Richard Engler at the EPA where he talked about green solvents. I sent him an email asking my question and he sent me the link to an awesome paper from the folks at Pfizer Global Research and Development.
Alfonsi, K. et. al. "Green chemistry tools to influence a medicinal chemistry and research chemistry based organisation", Green Chem. 2008, 10, 31-36.
With a title like this, I'm not sure I ever would have found this!
Hi Barbara,
So, what's the greenest substitute for DEF or DMF?
Cheers,
Kyle
For any who are still interested in this thread...
"So, what's the greenest substitute for DEF or DMF?"
It depends on what properties one needs the solvent to fulfil.
In my mind, DMF is notable as a polar aprotic solvent with a high dielectric constant (36.7) and fairly high boiling point (152 °C). Propylene carbonate actually has higher dielectric constant (64), and boiling point (>240 °C, which can be a blessing and a curse) while being generally non-toxic (approved for use in cosmetics, food packaging in direct contact with foodstuff, etc. ), has a very low vapor pressure (limiting VOC and flammability concerns), and is water-soluble. The main drawbacks to this solvent are:
• it is quite viscous, (at 25°C, it comes in at 2.5 cP, it is on par with n-butanol and slightly more viscous than dmso, though it won't freeze until you chill it below -50°C),
• it is hydroscopic, and not very easy to dry once it has gotten wet.
• and it is not cheap (about the same as dmf).
Thanks Aaron!
Hopefully you sorted this Barbara, I think the "Pfizer Solvent Selection Tool" suggests Acetonitrile as an alternative to DEF or DMF, although maybe still not the best solvent. DMSO also appears to be a suggested alternative that's much "greener" with the higher boiling point as well.
Might be an alternative to look into?