Sciencemadness Discussion Board

Chloroform in ether synth?

Jackson - 11-2-2019 at 08:47

Could chloroform be used in a Williamson ether synthesis? Would a reaction with sodium ethoxide produce something like tri ethoxymethane or would it stop reacting after the first or second ethoxy group was added?

DavidJR - 11-2-2019 at 08:55

Yes, this is one way to produce triethoxymethane, also known as triethyl orthoformate.

fusso - 11-2-2019 at 10:07

Nurdrage made (MeO)3CH in this vid. I believe Et version can be made this way too.
https://www.youtube.com/watch?v=TmUNTkP2nw0

Jackson - 12-2-2019 at 08:46

Could lithium metal be used in substitution for sodium metal? Just because lithium can be obtained from batteries and it's something that I have access to because of that. I could have access to sodium, but I already have lithium so if it can be used that would be preferable.

fusso - 12-2-2019 at 09:38

I think so, the alkali ion is only a counterion and changing it have little effect on nucleophilic substitution.

Sigmatropic - 12-2-2019 at 11:40

Agree with fusso, Except that the oxygen lithium bond is stronger than sodium oxygen. In my experience*, lithium alkoxide are less potent nucleophiles than sodium alkoxides. Generally requiring additives or polar aprotic solvents to work, if I recall the short literature search I did at the time.

*in the comparison between the two step procedure of an organolithium with a benzophenone in THF, acidic work-up to the alcohol then NaH/DMF, alkyl tosylate to give an ether and the single pot procedure of organolithium, benzophenone, then alkyl tosylate all in THF, which after isolation gave the alcohol as the primary product.
Could've been the solvent during alkylation, could've been the difference between sodium and lithium.

[Edited on 12-2-2019 by Sigmatropic]