I am looking to dissolve Boc-protected benzimidazole, 1,3-propane sultone, and potassium hydroxide in DMF. However, i noticed that potassium hydroxide is insoluble in DMF? why might this be? the original publication is using DMF.. is it supposed to remains insoluble?
I'm surprised you're having trouble as DMF is relatively polar. You've narrowed it down to definitely the KOH not dissolving in the DMF? I wonder, are you using the same concentrations? Is it dry DMF (that is, kept under inert atmosphere and water removed) or regular DMF (exposed to atmospheric water by opening / closing regularly without inert atmosphere)?
Depending on the reaction you're trying to do, I've also heard people pre-dissolving the KOH in a small amount of ethanol or water before adding to your reaction. Then again, I don't know what reaction you're attempting and if a potentially nucleophilic solvent might be an issue for you.
Good luck!