Lithium aluminum hydride, danger

Perfluorosuccinamide-Lithium Aluminum Hydride (Danger of Explosion). In an attempt to reduce perfluorosuccinamide to the corresponding diamine, it was added to an ether soln of lithium aluminum hydride in a nitrogen atm. Hydrolysis was then attempted, but as a second drop of w was added, a violent expln and ether fire resulted. It was shown that the diamide and the lithium aluminum hydride reacted to give an unstable complex which detonated at room temp Ref T.S. Reid G.H. Smith, C EN 29,3042 (1951) CA 46, 3279 (1952)... 

Lithium aluminum hydride, LiAIH4/ is another reducing agent often used for reduction of aldehydes and ketones. A grayish powder that is soluble in ether and tetrabydrofuran, LiAlH4 is much more reactive than NaBH4 but also more dangerous. It reacts violently with water and decomposes explosively when heated above 120 °C. 

The distillation of ethers from lithium aluminum hydride occasionally leads to an explosion. The exact cause is not known, but C02 may be involved. The danger can be minimized by predrying the ether with calcium hydride and then using a minimum amount of LiAlH for final distillation. Also, the distillation should be performed behind a blast shield, and the still pot should never be allowed to go dry. Frequently, a safe but powerful desiccant, such as benzophenone ketyl or sodium-potassium alloy, may be used in place of LiAIH4. 

Processes for synthesizing short-acting tryptamines are fairly simple and don t require much in the way of equipment, but they involve a risk of explosion. Also, purchases of several of the source materials are watched by the DEA. One of these is lithium aluminum hydride (LiAlH4), which is dangerous if it comes in contact with water molecules, as is usually required at the end of these processes. A chemist describes an experiment ... 

Caution Lithium aluminum hydride is sensitive to mechanical shock and very reactive towards moisture and other protic substances its dust is very irritating to skin and mucous membranes. It should not be allowed to come into contact with metallic species or apparatus, including metal spatulas, because of the potential danger of metal ion-promoted detonation. 

Unless special precautions are taken, lithium aluminum hydride reductions can be very dangerous. You should consult an appropriate laboratory manual before attempting such a reduction, and the reaction should be carried out on a small scale. 

More recently, sodium bis(2-methoxyethoxy) aluminum hydride (NaAlH2(OCH2CH20CH3)2, sUucture 40, available in toluene solution under the commercial name of Synhydride ), has been extensively used in replacement of the more dangerous lithium aluminum hydride as reduaion agent in the chemical industry and, specifically, in the polymerization of CL at temperatures below 170 °C ... 

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