so I've been wondering why the use of 5 equivalents of Et3N in this case of a Swern-oxidation is necessary. I have done this reaction succesfully quite a few times now, but all the literature uses 5 equivalents as well. I am fully aware of the mechanism (shown below). I can explain one eq. for the HCl that emerges in step one: And in the second step we need the base to form the sulfurylide:
but this should not be a equilibrium as the Ylide has no net charge and in my opinion is more stable. If it were to just enhance the reactivity a bit, I'd think that 2 more eq. (so 3 eq. in total) are sufficient.
I hope you can help me with this.