Why is THF a more favourable solvent in organometallic chemistry?

[pez]

So we did a reaction in the lab where we reacted SiCl₄ with Me₃SiCl and lithium metal in diethyl ether to form Si(SiMe₃)₄. The literature said we should use THF, but we had no dry THF, so our lab assistant said we should use diethyl ether. The reaction did not work at all, but in our lab report we have to explain why it did not work. It probably has something to do with the solvent we used, but I don't really know what exactly? Any ideas? Thanks in advance!

10.1039/D₁DT03375A (we were suppose to follow the steps in this paper)

[Terichrans]

So we did a reaction in the lab where we reacted SiCl₄ with Me₃SiCl and lithium metal in diethyl ether to form Si(SiMe₃)₄. The literature said we should use THF, but we had no dry THF, so our lab assistant said we should use diethyl ether. The reaction did not work at all, but in our lab report we have to explain why it did not work. It probably has something to do with the solvent we used, but I don't really know what exactly? Any ideas? Thanks in advance!

10.1039/D₁DT03375A (we were suppose to follow the steps in this paper)

I think it is due to using diethyl ether instead of dry THF. THF has better coordination properties with lithium, which helps to create the necessary reaction intermediates. Diethyl ether is weaker and if not completely dry, can react with SiCl₄ or Me₃SiCl, preventing the reaction from occurring.

[barkerxavierr]

Ah, the classic solvent swap gone wrong in organometallic chemistry! My first thought is that diethyl ether is just a less polar solvent than THF, which could significantly impact the solubility of your lithium or the intermediates. Also, THF is often preferred for these types of reactions due to its ability to solvate cations more effectively, stabilizing reactive species that ether just can’t handle.

[otdoglovers]

That makes sense—THF is more polar and coordinates better with lithium, which is why it supports the formation of the necessary intermediates. Diethyl ether can sometimes interfere if it’s not completely dry, and it just doesn’t stabilize reactive species as well. Your reaction likely failed because the solvent couldn’t provide the right environment for the lithium and intermediates to do their job.