Air/Moisture Sensitive Filtrations

Introduction to the problem of separating solids from solutions when either component is air or moisture sensitive. Overview of available filtration methods to protect compounds from air exposure.

Use a Büchner funnel with gasket and filter flask under vacuum in a glove box environment. Discuss limitations including solvent fume accumulation and difficulty of working through glove ports.

Set up a fritted funnel with Teflon stopper under positive nitrogen pressure, using a cannula inlet and bubbler outlet to maintain inert atmosphere. Pour the solution through the funnel to separate solid from liquid while preserving the filtrate.

Purge the filter funnel system with nitrogen gas to push the filtered solution into the receiving flask while maintaining air-free conditions throughout the transfer.

Cut a 1.5 to 2-inch square of filter paper and fold it around a needle or cannula tip. Wrap the filter paper tightly with Teflon tape starting from the bottom, ensuring no creases remain exposed, then secure a septum at the base.

Insert the filter cannula into a flask containing the compound under positive nitrogen pressure. Push the solution through the filter cannula into a receiving flask with a bubbler to maintain inert atmosphere and retain the solid in the original flask.

Once filtration is complete, reverse the process by removing the cannula while maintaining nitrogen pressure. Swap the inlet line for a septum to seal the receiving flask and preserve the air-free conditions of the filtered solution.