Abstract
Na and Na/K alloys in the liquid phase can be absorbed into amorphous silica gel at
loadings up to 40 wt%. Further heating of these so-called stage 0 materials at 150
or 400 °C furnishes stage I and stage II materials, respectively, as free-flowing
powders that can be handled under much safer conditions than the corresponding starting
materials. Stage I Na and Na2K possess valuable reducing properties and they have found a variety of low impact
applications in organic synthesis, including, e.g., the reductive deprotection of
several functional groups, the development of safer protocols to operate the Bouveault–Blanc
and the Birch reductions, and a new and particularly efficient approach to the Grignard
and Darzens reactions.
1 Introduction
2 Reductive Deprotection Procedures
3 Bouveault–Blanc Reduction of Esters
4 Ammonia-Free Birch Reductions
5 Synthesis of Alkyldiaryl- and Dialkylarylphosphines
6 C–C Bond Forming Reactions
7 Further Applications
8 Conclusion
Key words
alkali metal - sodium - potassium - silica gel - reduction - electron transfer - green
chemistry - low impact
