Safe and Powerful Reductant
Researchers at the University of California have synthesized a family of compounds which have very strong reduction properties and are also inexpensive and exceptionally safe.
Since 1947 the standard high-powered reductant available has been lithium aluminum hydride, but its violent reaction with air, water, and other compounds makes it a dangerous reagent. This pyrophoric property has been especially troublesome in industry where large quantities are needed. Safer alternatives such as OMH1 and vitride have been created, only with weakened reduction capabilities. These reductants all produce large quantities of gel by-product, and some produce a flammable gas, or toxic alcohol.
The newly synthesized compounds, in stark contrast, are not pyrophoric and do not react explosively with air or water; they react only slowly with methanol or any other acidic compounds with a pKa above 4.0. They can be stored under nitrogen at 25*C for six months without undergoing any decomposition or loss of hydride activity. Also, the UC compounds do not destabilize or melt at temperatures in excess of 300*C. These reductants have even been used safely in undergraduate laboratories.
Large scale reduction reactions with these compounds produced easily isolable products in both high yield and purity (all >80% and many >95% reduced product), comparable with lithium aluminum hydride. No gel and no toxic byproducts are produced.
These new reductants are selective; esters, lactones and anhydrides are cleanly reduced at ambient temperatures to their corresponding alcohols, while carboxylic acids are not reduced. They also reduce a wide range of functional groups including amides, epoxides, oximes, nitriles, and halides. Chiral versions of the reductants can also be prepared for asymmetric reactions. Unlike some hydrides (like sodium borohydride), the UC compounds are soluble in ether solvents.
In large scale production, these new reductants will be not only safer, but also cheaper to synthesize. There is likely to be a considerable advantage in reducing production costs, with the expected price of the UC compounds (estimated to be $150.00 per lb.) being nearly half that of current prices for lithium aluminum hydride ($250.00 per lb.) or sodium borohydride ($300.00 per lb.).
US 5,466,798 [MORE INFO
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