Chemistry - A European Journal
10.1002/chem.201705366
aggregates. Poisoning studies indicated the formation of a hetero-
topic catalyst which was characterized by TEM, EDX, and DLS.
This protocol constitutes the most practical Co-catalyzed hydro-
genation method of C=C and C=X bonds. We currently investigate
applications of this catalyst to related reductive transformations.[25]
Figure 2. Anthracene-stabilized Co particles (left); magnetic separation of
Co particles (middle); Co precipitate after reduction in the absence of
substrate and anthracene (right).
Acknowledgement
This work was financed by the Deutsche Forschungsgemeinschaft
(DFG, JA 1107/6-1). We thank Dr. Uttam Chakraborty, Michaela
Guter, Hannes Sterzel, and Martin Eisenhofer for technical assistance.
Received: ((will be filled in by the editorial staff))
Published online on ((will be filled in by the editorial staff))
Keywords: cobalt · nanoparticles · hydrogenations · hydrides ·
alkenes · imines · ketones
[
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Figure 1. TEM measurements. A: Relative Co amount of particle
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and scales with Co content per irradiated volume element, a.u. = arbitrary
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distribution of 124 particles. D, top: Atomically resolved HR-TEM image of [2]
two crystalline particles with corresponding diffractogram (inset). D, bottom:
EDX spectrum of single particles.
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Experimental Section
General methods of catalytic hydrogenation.
Protocol B: In an argon-filled glovebox, a flame-dried 4 mL vial
[
[
4]
5]
was charged with CoBr
THF (1 mL) and n-pentadecane (GC-FID reference, 0.2 mmol).
LiEt BH (0.018 mmol, 1 M, THF) was added dropwise with a
2
(0.006 mmol), the substrate (0.2 mmol),
3
Hamilton® syringe, and the pale blue solution changed to black.
After 10 min, the vial was transferred to a high-pressure reactor
which was sealed and removed from the glovebox. The reactor was
purged with H
were set. After the indicated reaction time, the vial was retrieved
and the reaction hydrolyzed with saturated aqueous NH Cl (1 mL)
for alkenes or NaHCO (1 mL) for ketones and imines, respectively.
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Protocol C: In an argon-filled glovebox, a flame-dried 4 mL vial
was charged with CoBr (0.006 mmol), anthracene (0.06 mmol),
THF (1 mL) and n-pentadecane (GC-FID reference, 0.2 mmol).
LiEt BH (0.018 mmol, 1 M, THF) was added dropwise with a
2
(3 × 3 bar) and reaction pressure and temperature
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1
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2
3
Hamilton® syringe, and the pale blue solution changed to black.
After 10 min, the substrate was added. See protocol B for
hydrogenation and work-up. For product isolation, 1 mmol of the
starting material was used (fivefold scale). The crude mixture was
[
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2
purified by flash chromatography (SiO , pentane / ethyl acetate).
4
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