[DoctorDomo]

Am I right in thinking that relatively weak bases such as sodium carbonate, are far more effective at deprotonating substrates when the solvent used is an aprotic one such as DMSO or DMF? My reasoning being that the weak base will react with any temporarily dissociated proton from the solvent. However what confuses me is that weak bases like NaCO3 wouldn't be able to say convert isopropyl alcohol into its alkoxide salt (in significant quantities at least), so how does the presence of a labile proton lower the weak bases ability to deprotonate your starting material?

[clarkstill]

You are right, they are stronger bases in aprotic solvents.  Although incapable of formally deprotonating an alcohol solvent, sodium carbonate will form multiple hydrogen bonds to the protic solvents, stabilizing it and making it less basic, as well as surrounding it with a coordination sphere that provides an additional steric barrier.

[DoctorDomo]

Thanks a lot, for the answer as well as the additional info about hydrogen bonding. I assume this means that organic compounds which can't form hydrogen bonds will be less soluble than they usually would be in the aprotic solvent, so if the volume of the solvent is right, ones product might precipitate out. I haven't observed this happen though, instead it seems to be only the carbonate that precipitates out. I suppose the same explanation applies though, when the alcohol (or other hydrogen bonding substrate) gets consumed, the carbonate becomes less soluble in the aprotic solvent. An example of where I observed this is converting alcohols to ethers, the carbonate seems to precipitate out as the alcohol is consumed.