Workup for Aluminum Hydride Reductions

• To work up a reaction containing x g lithium aluminum hydride
  1. Dilute with ether and cool to 0°C
  2. Slowly add x mL water
  3. Add x mL 15 % aqueous sodium hydroxide
  4. Add 3x mL water
  5. Warm to RT and stir 15 min
  6. Add some anhydrous magnesium sulfate
  7. Stir 15 min and filter to remove salts
• To work up a reaction containing x mmol of an agent such as Diisobutyl aluminum hydride (Dibal):
  1. Dilute with ether and cool to 0°C
  2. Slowly add 0.04x mL water
  3. Add 0.04x mL 15 % aqueous sodium hydroxide
  4. Add 0.1x mL water
  5. Warm to RT and stir 15 min
  6. Add some anhydrous magnesium sulfate
  7. Stir 15 min and filter to remove salts

Rochelle's Salt (Curly Arrow), Also find discussion of other strategies in the comments thread on this page.

Glaubler's Salt (Na2SO4•10H2O)

• Glauber's Salt can be purchased or made from recrystallizing sodium sulfate from water
• Cool your reaction to 0 °C (or lower depending on the scale/equivalents of LAH)
• Carefully add Glauber's salt until hydrogen evolution is no longer evident, then add some more
• Warm to rt and stir 15 min
• Filter over Celite

Acetic Acid Quench

• Make sure your product is not acid-sensitive
• Carefully add your reaction to a cold (0 °C) dilute aqueous solution of acetic acid while stirring

For a detailed article describing LAH reduction protocols, see

“A Safety Guidance Document for Lithium Aluminum Hydride (LAH) Reduction: A Resource for Developing Specific SOPs on LAH Manipulations” by Tilak Chandra* and Jeffrey P. Zebrowski
ACS Chem. Health Saf. 2024, 31, 162–171; https://pubs.acs.org/doi/10.1021/acs.chas.3c00102