They don’t have to ditch them; we just need to make energy cheap enough to properly recycle them.
I’m not remotely surprised, nor am I particularly impressed by the methodology of this study. DCM remains popular because it’s cheap and has great properties as an organic solvent (not flammable, low polarity, low boiling point). Really the only thing that isn’t great about it is that it’s derived from petroleum and carries a shit load of chlorine.
Without strong incentives to move, like a regulatory tax, where’s the financial incentive to find greener alternatives in reactions where “do it in DCM” has been the canonical answer for a hundred years?
DCM is also about the only good solvent left that is also resistant to lewis acids. I think that some people were pushing for benzotrifluoride as a replacement, but it just straight up doesn’t work as well where i tried it
Tbf before “do it in DCM” was “do it in CCL4” or “do it in benzene”, DCM just works without nuking operator’s liver
Lots of these new green solvents are also annoyingly polar so perhaps they can be used as replacements of other polar solvents but not anything else. I’m not using cyrene, fuck that
TFA is used because it works and is shelf-stable. Replacements like HCl in ether or ethyl acetate are bitch to make and when these can be bought, they have to be refrigerated all the way. Straight up not worth the effort on small scale
I fully agree. My personal experience with chemistry tells me that these people are not known for using these solvents out of spite, they use what works because they have specific properties and minimize personal risks when working in a lab, especially in an small-scale experimental setting where the used volumes of solvents are limited and changing them might bite into the sometimes meager amount of product you might get out of a reaction.
If everything goes well and you can replace the solvent for a greener substitute in an industrial scale process while still getting acceptable efficiency, i don’t think any chemist would disagree to switch. That they still use these solvents simply shows that some properties aren’t easily replicated.
