Pd/C and Hydrogenation

Pd/ C Hydrogenations Danger comes from the active catalysts – Absorb hydrogen gas – Can spark spontaneously and may ignite on exposure to air – Readily causes ignition of flammable solvents in the presence of air. – Use in presence of H 2 gas, sometimes at high pressure and temp. – In the event of fire, contain it with water Types of Catalysts – Degussa – safest – Wet – safer. Higher % of water – Dry Perry, David. Hazards in Hydrogenation. Do not operate near flammable materials

Correctly done, these reactions can be routinely run safely – Weigh and add catalyst first – Flush vessel with nitrogen. Handle Pd/C under inert atmosphere. – Add solvent. (Degas solvent with large scale > 100 mL) Use ethanol, not methanol (very flammable, invisible flame) – Flush reaction vessel with N 2, run reaction, repeat flush with N 2 – Remove Pd/C through filtration (celite on glass frit), and cover with wet sand. Filter cake should never be allowed to dry, and the moist material should be added to a large quantity of water and disposed of properly. – Dispose of waste in dedicated container that contains water. Know how to use the equipment – Don’t over-pressurize – Don’t use damaged equipment or glassware. Pd/ C Hydrogenations Prudent Practices in the Laboratory: Handling and Disposal of Chemicals Laboratory Chemical Safety Summary: Palladium on Carbon

Pd/C According to Prudent Practices in the Laboratory, palladium on carbon catalysts containing adsorbed hydrogen are pyrophoric, particularly when dry and may ignite on exposure to air 4