Abstract
This account summarizes our recent research on green functional
group transformations using easily prepared supported ruthenium
hydroxide catalysts [Ru(OH)x /support,
support = Al2 O3 , TiO2 ,
or Fe3 O4 ]. Various kinds of functional
group transformations, e.g. the oxidation (oxidative dehydrogenation)
of alcohols and amines, hydrogen-transfer reactions, such as racemization
and reduction, and the hydration of nitriles, can be promoted by
the concerted activation of the substrates (including alcohols,
amines, and nitriles) by the Lewis acid and Brønsted base
sites on the Ru(OH)x /support catalyst. In addition,
we have successfully developed three novel catalytic transformations
with the Ru(OH)x /support catalysts: (1) the
oxygenation of primary amines to give amides, (2) the direct oxidative
synthesis of nitriles from primary alcohols and ammonia, and (3)
the N-alkylation of ammonia (or its surrogates) with alcohols to
produce symmetrically substituted tertiary or secondary amines.
The catalyses for these transformations are truly heterogeneous,
and the catalysts retrieved after the transformations can be reused
with retention of their high catalytic performance.
1 Introduction
2 Preparation and Characterization of Supported Ruthenium Hydroxide
Catalysts
3 Oxidation of Alcohols and Amines
4 Hydration of Nitriles
5 Oxygenation of Primary Amines To Give Amides
6 Direct Oxidative Synthesis of Nitriles from Primary Alcohols
and Ammonia
7 N-Alkylation of Ammonia with Alcohols To Give Tertiary or
Secondary Amines
8 Conclusion
Key words
concerted activation - Lewis acids - Brønsted
bases - heterogeneous catalysis - ruthenium hydroxide