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Author: Subject: Aluminum hydride from LiAlH4
FormerBeagle
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[*] posted on 23-6-2019 at 15:28
Aluminum hydride from LiAlH4


I have seen reference to adding small amounts of 100% sulfuric acid to LiAlH4 to make a more active reducing agent. My understanding is that this produces aluminum hydride. In my own work, I have used the addition of AlCl3 to LAH for more stubborn functional groups. Is there some advantage to the sulfuric acid method?
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draculic acid69
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[*] posted on 24-6-2019 at 00:25


What does adding alcl3 to LAH do?
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FormerBeagle
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[*] posted on 24-6-2019 at 14:29


It increases the reducing activity quite a bit by converting it to aluminum hydride. For instance, for N-monoalkyl tryptamines, LAH by itself only sluggishly reduced the amides. The addition of AlCl3 dramatically decreased reaction times.
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Keras
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[*] posted on 24-6-2019 at 22:34


You can also boost the reducing power of sodium borohydride using various mineral additives. IMO, sodium borohydride is much cheaper and easier to store and handle than lithium-aluminium hydride.
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