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Why is THF a more favourable solvent in organometallic chemistry?
Posted: Mon Apr 14, 2025 5:06 am
by 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)
Re: Why is THF a more favourable solvent in organometallic chemistry?
Posted: Mon May 12, 2025 11:52 pm
by Terichrans
pez wrote: ↑Mon Apr 14, 2025 5:06 am
So we did a reaction in the lab where we reacted SiCl
4 with Me
3SiCl and lithium metal in diethyl ether to form Si(SiMe
3)
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/D
1DT03375A (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.
Re: Why is THF a more favourable solvent in organometallic chemistry?
Posted: Mon Aug 04, 2025 1:13 am
by 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.
Re: Why is THF a more favourable solvent in organometallic chemistry?
Posted: Sat Sep 20, 2025 1:42 am
by 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.
Re: Why is THF a more favourable solvent in organometallic chemistry?
Posted: Thu Sep 25, 2025 11:05 pm
by tomtext
The reaction failed because diethyl ether (Et₂O) is a much poorer ligand for Li⁺ than THF, so the lithium metal surface is not kept clean and the electron-transfer step that generates the silyl radical (or silyl anion) essentially stops.
In other words, the solvent is not just a passive medium; it has to solvate Li⁺ and stabilise the electron-transfer intermediate. Et₂O does this so weakly that the passivating LiCl layer on the metal is never disrupted, and no Si–Si bond formation occurs.