Red-Al

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Red-Al
Structural formula of red-Al with explicit hydrogens
Identifiers
Abbreviations SMEAH
CAS number 22722-98-1 N
PubChem 16684438
ChemSpider 21169529 YesY
Jmol-3D images Image 1
Image 2
Properties
Molecular formula C6H16AlNaO4
Molar mass 202.16 g mol−1
Appearance Transparent crystals
Hazards
Main hazards Unstable toward water
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Red-Al, or sodium bis(2-methoxyethoxy)aluminumhydride, is an organoaluminium compound with the formula NaAlH2(OC2H4OCH3)2. The name which is a trademark of Sigma-Aldrich refers to its being a Reducing aluminium compound. It is used almost exclusively as a solution in toluene, and is used as a reagent in organic synthesis. The compound features a tetrahedral aluminium center attached to two hydride and two alkoxides, the latter derived from 2-methoxyethanol.1

Some common functional group reductions using Red-Al can be found below:

Red-Al Reductions.png

Red-Al is a potent hydride reducing agent. It converts carboxylic acid anhydrides and lactones to diols. Amides, nitriles, imines, and most other organonitrogen compounds are reduced to the corresponding amines. Nitroarenes can be converted to azoxyarenes, azoarenes, or hydroazoarenes depending on the reaction conditions.2

Comparison with lithium aluminium hydride

As a reagent, Red-Al is comparable with LiAlH4. In contrast with lithium aluminium hydride, Red-Al exhibits good solubility in aromatic solvents. Thus, a 70 wt.%-solution in toluene is commercially available. Its solutions are also more stable to moisture and air than LiAlH4 and more thermally stable, tolerating temperatures up to 200 °C. The reagent can be modified to affect partial reductions.2

References

  1. ^ Casensky, B.; Machacek, J.; Abraham, K. (1971). Collection of Czechoslovak Chemical Communications 36: 2648. 
  2. ^ a b Gugelchuk, M.; Silva, L. F. III; Vasconcelos, R. S.; Quintiliano, S. A. P. (2007). "Sodium Bis(2-methoxyethoxy)aluminum Hydride". Encyclopedia of Reagents for Organic Synthesis. New York: John Wiley & Sons. doi:10.1002/047084289X.rs049.pub2. 

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