208
R. V. Jagadeesh
R
R
CN
5 bar O 2
130-150
o C, 15-30h
OH
Co 3 O 4 /NGr@C
>80 Aromatic, heterocycle,
allylic and aliphatic nitriles.
Up to 98% yield.
Aq. NH 3
+
CN
F
F
F
Yield = 95%
CN
Cl
Cl
94%
CN
94%
CN
Cl
NO 2
89%
CN
O
O
NO 2
92%
CN
NH 2 93%
CN
S
F
F
F
94%
94%
S
CN
CN
B
O
O
CN
92%
N
CN
O 2 N
92%
CN
O
97%
CN
97%
O
O
O
CN
F
F
F
98%
CN
O
F
F
F
96%
CN
Si
88%
S
CN
89%
CN
86%
CN
96%
CN
96%
O
N
N
CN
N
O
F
F
F
93%
N N
CN
Cl
F
F
F
94%
N
S
CN
94%
CN
O
O
O
N
94%
N
N
CN
O
F
F
F
95%
N N
CN
O
O
95%
Cl
CN
N
N
91%
CN
S
O
O
N
O
95%
CN
Me
82%
CN
92%
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Scheme 6.11 Green synthesis of nitriles using Co 3 O 4 /NGr@C catalyst
the hydrogenation of nitro compounds and imines [12, 13]. However, the pyrolysis of Co-phenanthroline complexes on oxidic supports such as Al 2 O 3 and silica
produced more active catalysts, which allow for the hydrogenation of other functional molecules [19–21]. Upon pyrolysis of Co(OAc) 2 -phenanthroline complex on
α-alumina produced cobalt-oxide/metallic cobalt nanoparticles giving rise to a coreshell structure and nitrogen doped graphene layers (Co 3 O 4 –Co/NGr@α-Al 2 O 3 ) [19].
This supported alumina cobalt nanocatalyst displayed high activity and selectivity
for the hydrogenation of quinolines to tetrahydroquinolines and indoles to indolines
[19] (Scheme 6.12), nitriles to amines (Scheme 6.13) [20] and carbonyl compounds
to alcohols [20] (Scheme 6.13).
Fascinatingly, all of the studied aromatic nitriles have been hydrogenated at 85 °C
with 40 bar of hydrogen [20]. Even aliphatic nitriles, which are difficult to reduce,
were also smoothly hydrogenated and produced the corresponding aliphatic amines in
excellent yields [20]. Outstandingly, hexamethylenediamine, an important feedstock
N
Co3O4-Co/NGr@ -Al2O3
(4 mol%)
+ H2
Toluene, 120-140 o C, 48 h
(2-5 MPa)
R1
R2
N
H
R1
R2
N
N
Co3O4-Co/NGr@ -Al2O3
(8 mol%)
+ H2
Toluene, 120 o C, 48 h
(2 MPa)
R1
R1
R'
R'
R2
R2
Scheme 6.12 Co 3 O 4 -Co/NGr@α-Al 2 O 3 catalyzed hydrogenation of N-heteroarenes
R. V. Jagadeesh
R
R
CN
5 bar O 2
130-150
o C, 15-30h
OH
Co 3 O 4 /NGr@C
>80 Aromatic, heterocycle,
allylic and aliphatic nitriles.
Up to 98% yield.
Aq. NH 3
+
CN
F
F
F
Yield = 95%
CN
Cl
Cl
94%
CN
94%
CN
Cl
NO 2
89%
CN
O
O
NO 2
92%
CN
NH 2 93%
CN
S
F
F
F
94%
94%
S
CN
CN
B
O
O
CN
92%
N
CN
O 2 N
92%
CN
O
97%
CN
97%
O
O
O
CN
F
F
F
98%
CN
O
F
F
F
96%
CN
Si
88%
S
CN
89%
CN
86%
CN
96%
CN
96%
O
N
N
CN
N
O
F
F
F
93%
N N
CN
Cl
F
F
F
94%
N
S
CN
94%
CN
O
O
O
N
94%
N
N
CN
O
F
F
F
95%
N N
CN
O
O
95%
Cl
CN
N
N
91%
CN
S
O
O
N
O
95%
CN
Me
82%
CN
92%
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Scheme 6.11 Green synthesis of nitriles using Co 3 O 4 /NGr@C catalyst
the hydrogenation of nitro compounds and imines [12, 13]. However, the pyrolysis of Co-phenanthroline complexes on oxidic supports such as Al 2 O 3 and silica
produced more active catalysts, which allow for the hydrogenation of other functional molecules [19–21]. Upon pyrolysis of Co(OAc) 2 -phenanthroline complex on
α-alumina produced cobalt-oxide/metallic cobalt nanoparticles giving rise to a coreshell structure and nitrogen doped graphene layers (Co 3 O 4 –Co/NGr@α-Al 2 O 3 ) [19].
This supported alumina cobalt nanocatalyst displayed high activity and selectivity
for the hydrogenation of quinolines to tetrahydroquinolines and indoles to indolines
[19] (Scheme 6.12), nitriles to amines (Scheme 6.13) [20] and carbonyl compounds
to alcohols [20] (Scheme 6.13).
Fascinatingly, all of the studied aromatic nitriles have been hydrogenated at 85 °C
with 40 bar of hydrogen [20]. Even aliphatic nitriles, which are difficult to reduce,
were also smoothly hydrogenated and produced the corresponding aliphatic amines in
excellent yields [20]. Outstandingly, hexamethylenediamine, an important feedstock
N
Co3O4-Co/NGr@ -Al2O3
(4 mol%)
+ H2
Toluene, 120-140 o C, 48 h
(2-5 MPa)
R1
R2
N
H
R1
R2
N
N
Co3O4-Co/NGr@ -Al2O3
(8 mol%)
+ H2
Toluene, 120 o C, 48 h
(2 MPa)
R1
R1
R'
R'
R2
R2
Scheme 6.12 Co 3 O 4 -Co/NGr@α-Al 2 O 3 catalyzed hydrogenation of N-heteroarenes