Lithium Aluminium Tetrahydride , the powder is very fine, wear a mask! Pay attention to the used weighing paper and steel spoon! After the reaction finishes adding solvent, the excess tetrahydroaluminum lithium is destroyed with methanol and washed with dilute hydrochloric acid, but it is emulsified, and many flocculent solids are difficult to filter out with diatomaceous earth, and the washing with dilute sodium bicarbonate is also emulsification.
1. A better method is to quench water at low temperature to generate colloidal particles, filter, and then wash with solvent several times, combine the organic phases, wash, dry and concentrate.
2. Quench with water at low temperature, then add a large amount of magnesium sulfate to form small particles, and it is much easier to filter. If the reaction is small, try it.
3. After the reaction is completed, metered water is added, then magnesium sulfate is added to dry, and suction filtration can be done!
4. It is best to quench with NaOH solution, and then filter to remove the solution. Assume that the amount of LiAlH4 in the reaction is 1 g. After the reaction was completed, the reaction mixture was cooled to -10~0°C, and 1 mL of water was slowly added dropwise with stirring to quench the reaction. After completion, 1 mL of 10% NaOH solution was slowly added dropwise. The resulting solid was filtered off, washed with the reaction solvent for several times, and the filtrate was concentrated under reduced pressure to obtain the product. If necessary, the solid can be soaked and washed with ethanol or methanol, and concentrated to recover more products (mostly containing inorganic salts at this time). Generally the solids are suspended in the reaction solvent and are very easy to filter. Sometimes in the process of adding water, the reactant is relatively viscous, and some reaction solvents can be appropriately added to dilute. Note: The reaction is violent when adding water, a lot of heat is generated and gas is generated, so it must be slowly added dropwise. The order of water and NaOH should not be reversed, otherwise it may increase the adsorption of the product and affect the yield.