I am trying to form 2,2-diacetoxy acid using acetic anhydride and glyoxylic acid monohydrate (Scheme below)
I could not find a suitable synthetic protocol for this, so I just added 10 equivalents of acetic anhydride to 1 equiv. of glyoxylic acid monohydrate and refluxed the mixture at 140 °C. Now the limiting agent (glyoxylic acid monohydrate) is gone, but I am not sure with how to remove excess acetic anhydride; its boiling point is too high (139.8 °C) and the pressure of the rotovap in my lab isn't that strong (I tried removing toluene before, it only worked when I increased the water bath temperature to 70 °C).
Yes, I am aware that I can make an azetrope by adding toluene, which will have a lower boiling point, but that would still require the water bath temperature to be quite high and I'm scared that my product might be broken down or perturbed at such a high temperature. Should I add ~2 N HCl and extract my product with DCM? Any other tips or guidance? I'd appreciate any help.