Once I vacuum out the solvent I'll be left we a rigid film at the bottom of the flask. How can I collect this? Normally the solution is vacuumed in a chamber where the material is more accessible and can be scraped out with a razor blade. Chambers can be costly. Any ideas or has anyone ever seen a little scraping tool that would fit in the flask? Thank you!!!

This depends on the flask. Would a spatula not suffice? What are you using you product for?

Depends on the amount, but redissolving it in as little solvent as possible, sucking it out with a pasteur pipette and transfer it in a small container, blowing an airstream over it to evaporate the solvent can work. That's how I recover 100 mgs of compound.

Depends on the amount, but redissolving it in as little solvent as possible, sucking it out with a pasteur pipette and transfer it in a small container, blowing an airstream over it to evaporate the solvent can work. That's how I recover 100 mgs of compound.

 

 

This is what I would normally do as well (it is especially prudent for working on mg scale).

 

My post was made under the assumption that the OP was not necessarily transferring between vessels. If transferring from one flask to another, this is certainly the best method. Though if you're transferring to something that has a ground glass joint on it or a neck that could fit rubber hosing, you could forgo the air stream and just connect it to vacuum again, provided the glass could withstand it.

The final product is an oil that easily traps the solvent in pockets. It must be vacuumed out completely. Sorry if I did not make that clear.