Co3O4 nanoparticles prepared by oxidative precipitation method: an efficient and reusable heterogeneous catalyst for N-formylation of amines

Article abstract of DOI:10.1007/s11164-016-2631-7

Abstract: N-formylation of different amines was carried out with formic acid in the presence of the Co₃O₄ nanoparticles as an efficient, stable heterogeneous catalyst to give the corresponding formamides under solvent-free conditions. This method has advantages over the reported methods such as high yields, mild conditions, easy work-up and short reaction times. The catalyst was characterized by different techniques such as XRD, SEM and FT-IR spectroscopy. Graphical Abstract: [Figure not available: see fulltext.]

Full text of DOI:10.1007/s11164-016-2631-7

Res Chem Intermed
DOI 10.1007/s11164-016-2631-7
Co3O4 nanoparticles prepared by oxidative
precipitation method: an efficient and reusable
heterogeneous catalyst for N-formylation of amines
Ahmad Poursattar Marjani1 Seyed Ali Hosseini1
•
•
Zahra Shokri1 Nasim Maleki1
•
Received: 23 June 2016 / Accepted: 26 June 2016
Ó Springer Science+Business Media Dordrecht 2016
Abstract N-formylation of different amines was carried out with formic acid in the
presence of the Co3O4 nanoparticles as an efficient, stable heterogeneous catalyst to give
the corresponding formamides under solvent-free conditions. This method has advan-
tages over the reported methods such as high yields, mild conditions, easy work-up and
short reaction times. The catalyst was characterized by different techniques such as
XRD, SEM and FT-IR spectroscopy.
Graphical Abstract
NH2
NHCHO
CH3
NH2
NHCHO
CH3
Co3O
4 Nanoparticles
Cl
Cl
NHCHO
oC
HCO
NHCHO
H,
40
NH2
NH2
2
OHCHN
H2N
Keywords Amines Á Co3O4 nanoparticles Á Formic acid Á N-formylation Á
Heterogeneous catalyst
&
Ahmad Poursattar Marjani
a.poursattar@gmail.com; a.poursattar@urmia.ac.ir
1
Department of Chemistry, Faculty of Science, Urmia University, Urmia 57154, Iran
123

A. P. Marjani et al.
Introduction
The formyl group is one of the most important groups for the protection of amines
[1]. Formamides, the corresponding products, are important intermediates which
have been widely applied in the synthesis of fine chemicals [2, 3] and
pharmaceutically important compounds such as fluoroquinolines [4], imidazoles
[2], 1,2-dihydroquinolines [5], nitrogen-bridged heterocycles [6], oxazolidinones
[7], and cancer chemotherapeutic agents [8]. Also, formamides are applied as
catalysts in the allylation [9], hydrosilylation [10] and reaction of carbonyl
compounds. They are used as reagents in Vilsmeier formylation [11] and in the
synthesis of formamidines and isocyanides [12]. A large number of methods have
been reported for the N-formylation of amines [13–22], but most of them suffer
from major drawbacks such as thermal instability, sensitivity to moisture,
application of toxic and expensive formylating agents and catalysts, high
temperatures, prolonged reaction times, harsh reaction conditions, formation of
byproducts, low yields and tedious work-up. Therefore, an alternative procedure
which is effective, simple, green and employing available and inexpensive reagents
is vital. Currently, formic acid has been known [16, 23–26] as a suitable formylating
agent because of its lower toxicity, inexpensive and easy practical applicability.
On the other hand, organic synthesis catalyzed by metal oxide nanoparticles [27]
has recently attracted more attention [28] because they are the frontiers between
homogeneous and heterogeneous catalysis [29]. The great advantages of these
nanocatalysts are their large surface area, magnetic, thermal and chemical properties
[30–32], high catalytic activity, recoverability, and improved selectivity [33, 34]. To
the best of our knowledge, N-formylation of amine catalyzed by nanocrystalline
Co3O4 has not been reported. Therefore, in this paper, we wish to focus on an
effective, convenient and practical procedure employing nano-Co3O4 to efficiently
catalyze N-formylation of amines (Scheme 1).
Experimental
Catalyst preparation
In the oxidative precipitation method, the same volumes (25 mL) of ammonia
solution and distilled water were mixed in a 250 mL two-necked flask mounted to a
reflux condenser. The flask was placed on a hot plate stirrer at 90 °C. After heating
for 10 min under constant magnetic stirring (300 rpm) and air blowing into the
Scheme 1 N-formylation of
amines with HCO2H/nano
Co3O4 system
123

Co3O4 nanoparticles prepared by oxidative precipitation…
solution, 15 mL of 1.0 mol L-1 cobalt nitrate solution was added dropwise using a
burette. The reaction was continued for 18 h. It was then centrifuged and dried at
60 °C for 12 h.
General procedure for N-formylation of amines
To a mixture of HCO2H (4 mmol, 0.15 mL) and Co3O4 nanoparticles (0.015 g) was
added aniline (1 mmol), and then the reaction mixture was heated at 40 °C and
stirred with a magnetic stirrer. The progress of the reaction was monitored by TLC.
After the reaction was completed, EtOAc was added to the reaction mixture, and the
catalyst was removed by filtration. The organic solvent was then washed with H2O
(2 9 10 mL) and dried over anhydrous Na2SO4. After removal of the solvent, the
pure product was obtained. This was further purified by recrystallization with a
suitable solvent (ether or CHCl3).
General procedure for acetylation of amines
In a round-bottomed flask (25 mL) equipped with a magnetic stirrer, a mixture of
aniline (0.093 g, 1 mmol) and Co3O4 (0.006 g) was prepared. Acetic anhydride
(0.102, 1 mmol) was then added to the reaction mixture and stirring was continued
at room temperature for 3 min. The progress of the reaction was followed by TLC.
After the reaction completion, the products was extracted with EtOAc and filtered to
remove Co3O4. The organic solvent was then washed with H2O (2 9 10 mL) and
saturated NaHCO3 solution and then dried over anhydrous Na2SO4. The solvent was
removed under vacuum to afford the pure product.
Characterization and measurements of nanocatalysts
The characterization of the samples by X-ray diffraction was carried out on a
SIEMENS D5000 diffractometer. The infrared spectra of the samples were recorded
with a Bruker 27 in the range from 3900 to 400 cm-1 with 4 cm-1 resolution. A
scanning electron microscope (model EQ-C1-1) was used to obtain the SEM
images.
Results and discussion
Catalyst characterization
The structural property of the catalyst was characterized by XRD as shown in Fig. 1
and compared with JCPDS 78-1970 as a reference. The XRD pattern confirmed that
the structure of the sample is essentially polycrystalline Co3O4 phase. No other
phase except Co3O4 was found in the XRD pattern of the catalyst. The peaks at 2h
of 31.3°, 36.8°, 44.8°, 59.3° and 65.2° indicate the presence of (220), (311), (400),
(511) and (440) reflections for cubic Co3O4 spinel as indicated in Fig. 1 [35–37].
123

A. P. Marjani et al.
In addition, the mean crystallite size of Co3O4 spinel was estimated using the
full-width half-maximum of the characteristic diffraction peak (2h = 36.8°) through
the Scherrer formula. It was estimated to be 6 nm. Furthermore, the formation of
spinel structure during the synthesis of samples was confirmed by FT-IR (Fig. 2).
The appearance of two bands in the range 400–700 cm-1 in the IR spectra
corresponds the stretching vibration of metal oxygen bonds in the spinel structure
[38]. The bands around 500 cm-1 and between 600 and 700 cm-1 correspond to the
stretching band of cobalt-oxygen in the tetrahedral system (Td) and the octahedral
system, respectively. The strong bands around 1620–1650 and 1322 cm-1
correspond to the carboxylate and NO2 functional groups, respectively [39] The
broad band around 3300–3500 cm-1 is ascribed to the hydroxyl group of adsorbed
water by the KBr pellet [40].
In order to study the morphology and to determine the mean particle size of the
catalysts, an SEM image was taken from the sample (Fig. 3). It can be observed that
the particles of Co3O4 are nanotube-like (25–40 nm) as reported by Lou et al. [41]
for the synthesis of Co3O4 by the same method. More details and proofs for
nanotube morphology have been presented in their paper. By comparing the results
of the size from XRD and SEM, it is concluded that each particle of Co3O4 contains
4–7 crystallites.
N-formylation of amines with Co3O4 system
After the characterization of the nano-Co3O4, in order to optimize the reaction
conditions, we carried out the reaction of formic acid and aniline as a model
substrate in the presence of Co3O4 nanoparticles. The best result was obtained with
the aniline/formic acid molar ratio of 1–4 with 0.015 g of the Co3O4 under solvent-
free conditions (Table 1, entry 2). We also investigated the influence of different
solvents on the reaction rate and yield in the presence of Co3O4 nanoparticles, and
understood that formamide formation occurs faster under solvent-free conditions
than in the presence of a solvent (Table 1, entries 5–10).
Fig. 1 XRD of the synthesized cobaltite nanospinel
123

Co3O4 nanoparticles prepared by oxidative precipitation…
Fig. 2 FT-IR spectra of the synthesized cobaltite nanospinel
Fig. 3 SEM image of synthesis cobaltite nanospinel
Table 1 Optimization experiments for formylation of aniline with Co3O4 NPs under different conditions
Entry Co3O4
(mg)
HCO2H
(mmol)
Solvent
(mL)
Temperature
(°C)
Time
(min)
Conversion
(%)
1
2
15
15
15
10
15
15
15
15
15
15
4
4
3
4
4
4
4
4
4
4
S.F.
RT
40
40
40
40
40
40
40
40
40
30
4
90
97
95
80
40
40
60
60
20
80
S.F.
3
S.F.
20
4
S.F.
30
5
H2O
120
120
120
120
120
120
6
CH2Cl2
MeOH
EtOH
CH3CN
THF
7
8
9
10
All reactions were carried out with 1 mmol of aniline in 5 mL solvent
123

A. P. Marjani et al.
Table 2 Formylation of amines with HCO2H/nano Co3O4 system
Molar Ratio
Time Yield
(min) (%)
Entry
1
Substrate
Product
Subs./Ac2O/Cat.
1:3:0.015
1:3:0.015
4
95
2
10
92
3
4
5
1:3:0.015
1:3:0.015
1:3:0.015
10
8
94
91
93
8
6
7
1:3:0.015
1:3:0.015
15
10
92
91
8
1:3:0.015
10
91
9
1:3:0.015
1:3:0.04
6
89
90
10
20
11
12
1:6:0.04
1:6:0.04
15
20
91
89
13
1:6:0.04
12
91
14
15
No reaction
No reaction
1:6:0.04
1:6:0.04
All reactions were carried out at 40 °C
123

Co3O4 nanoparticles prepared by oxidative precipitation…
Table 3 Comparison of the formylation of aniline with the HCO2H/nano-Co3O4 system and other
reported systems
Entry Catalyst
Reductant
(mmol)
Time
(min)
Yield
(%)
Condition
Reusability
(times)
References
1
2
Basic Al2O3
HCO2H (3)
5
\98
40 °C
70 °C
9
–
[42]
[43]
Protic ionic
liquids
HCO2H (1.4) 60
97
3
5
Natrolite
zeolite
HCO2H
20
89
97
r.t.
–
–
[44]
[45]
Amberlite IR- HCO2H (3)
120
60 s
Microwaves
6
7
ZnO
HCO2H (3)
HCO2H (3)
10
99
91
70 °C
r.t.
3
–
[22]
[14]
PEG-400
(2 g)
5 h
8
Nano Co3O4
HCO2H (4)
4
95
40 °C
5
This work
100
90
80
70
60
50
40
30
20
10
0
1
2
3
4
5
Run Number
Fig. 4 N-formylation of aniline with the HCO2H/recycled nano-Co3O4 system
Scheme 2 Acetylation of
amines with the Ac2O/nano-
Co3O4 system
Based on the above observations, we next examined the scope and generality of
this method to other substrates, the results being summarized in Table 2.
The summarized results in Table 2 show that the reaction can tolerate a wide
range of amines carrying different substituents in the ortho, meta and para positions.
O-formylation of alcohol or phenol derivatives under these reaction conditions were
not successful. No reaction was observed with phenol and alkyl alcohol (entries 14
and 15). It was found that this reaction is chemoselective.
123

A. P. Marjani et al.
Table 4 Acetylation of amines with Ac2O/nano Co3O4 system
Molar Ratio
Time Yield
(min) (%)
Entry
1
Substrate
Product
Subs./Ac2O/Cat.
1:1:0.006
1:1:0.006
3
95
2
5
94
3
4
5
1:1:0.006
1:1:0.006
1:1:0.006
6
3
4
92
94
92
6
1:1:0.006
4
96
7
8
9
1:1:0.006
1:1:0.006
1:1:0.006
6
6
5
95
93
95
10
11
1:1:0.006
1:1:0.006
5
7
94
96
12
13
1:1:0.006
1:1:0.1
10
7
93
98
14
15
1:2:0.2
1:2:0.2
10
10
90
95
16
17
1:2:0.2
1:1:0.2
12
12
98
98
All reactions were carried out under solvent free condition at room temperature
123

Co3O4 nanoparticles prepared by oxidative precipitation…
The usefulness and capability of the HCO2H/nano-Co3O4 system in the
formylation of amines was highlighted by comparison of the obtained result for
PhNH2 with other reported systems (Table 3). This procedure shows a greater or
comparable efficiency compared with the other systems.
Recycling of Co3O4 (Cat.)
In addition, the catalytic activity of the recovered catalyst (Co3O4) was examined.
The catalyst was recycled up to 5 times for the synthesis of N-formylaniline without
significant loss of its catalytic performance, an important point in the domain of
green chemistry (Fig. 4).
Acetylation of amines with Co3O4 system
After applying Co3O4 nanoparticles for the N-formylation of amines, we replaced
formic acid by acetic anhydride (Scheme 2). We observed the formation of
acetamides with high yields, without any side products. The experimental
conditions and details are described in Table 4.
Based on the above observations, we found that all the amines were selectively
converted to the corresponding acetamides in high yields without any side products.
Interestingly, the substrates containing the –NH2 and –OH groups in the presence of
one equivalent of acetic anhydride produced the corresponding acetamides as sole
products; the hydroxyl moiety remained untouched (Table 3, entry 17). This may be
due to the –NH2 group having greater nucleophilicity than the –OH group. The
selective acetylation of a –NH2 group in the presence of –OH groups is of
considerable synthesis importance.
Conclusion
In conclusion, we have developed a novel and highly efficient method for N-
formylation of amines using nontoxic and inexpensive Co3O4 nanoparticles. The
advantages of this procedure include an operational simplicity, no requirement for
specialized equipment, very mild reaction conditions, high product yields, short
reaction times, the possibility of reusing the catalyst and compatibility with various
functional groups.
Acknowledgment The authors gratefully acknowledge the financial assistance from Urmia University.
References
1. J.C. Sheehan, D.D.H. Yang, J. Am. Chem. Soc. 80, 1154 (1958)
2. B.-C. Chen, M.S. Bendarz, R. Zhao, J.E. Sundeen, P. Chen, Z. Shen, A.P. Skoum-bourdis, J.C.
Barrish, Tetrahedron Lett. 41, 5453 (2000)
3. S. Kobayashi, K. Nishio, J. Org. Chem. 59, 6620 (1994)
4. A. Jackson, O. Meth-Cohn, J. Chem. Soc. Chem. Commun. 1319 (1995)
5. K. Kobayashi, S. Nagato, M. Kawakita, O. Morikawa, H. Konishi, Chem. Lett. 24, 575 (1995)
123

A. P. Marjani et al.
6. A. Kakehi, S. Ito, S. Hayashi, T. Fujii, Bull. Chem. Soc. Jpn. 68, 3573 (1995)
7. B.B. Lohray, S. Baskaran, B.S. Rao, B.Y. Reddy, I.N. Rao, Tetrahedron Lett. 40, 4855 (1999)
8. G.R. Petit, M.V. Kalnins, T.M.H. Liu, E.G. Thomas, K. Parent, J. Org. Chem. 26, 2563 (1961)
9. S. Kobayashi, M. Yasuda, I. Hachiya, Chem. Lett. 407 (1996)
10. K. Iseki, S. Mizuno, Y. Kuroki, Y. Kobayashi, Tetrahedron 55, 977 (1999)
11. Y. Han, L. Cai, Tetrahedron Lett. 38, 5423 (1997)
12. J. Martinez, J. Laur, Synthesis 979 (1982)
13. T. Jiang, X. Zhou, K. Taghizadeh, M. Dong, C.P. Dedon, Proc. Natl. Acad. Sci. USA 104, 60 (2007)
14. B. Das, M. Krishnaiah, P. Balasubramanyam, B. Veeranjaneyulu, D.N. Kumar, Tetrahedron Lett. 49,
2225 (2008)
15. J. Akbari, M. Hekmati, M. Sheykhan, A. Heydari, Arkivoc xi, 123 (2009)
16. A. Chandra Shekhar, A. Ravi Kumar, G. Sathaiah, V. Luke Paul, M. Sridhar, P. Shanthan Rao,
Tetrahedron Lett. 50, 7099 (2009)
17. P.G. Reddy, S. Baskaran, Tetrahedron Lett. 43, 1919 (2002)
¨
18. J. Deutsch, R. Eckelt, A. Kockritz, A. Martin, Tetrahedron 65, 10365 (2009)
19. J.-G. Kim, D.O. Jang, Bull. Korean Chem. Soc. 31, 2989 (2010)
20. M. Rahman, D. Kundu, A. Hajra, A. Majee, Tetrahedron Lett. 51, 2896 (2010)
21. O. Saidi, M.J. Bamford, A.J. Blacker, J. Lynch, S.P. Marsden, P. Plucinski, R.J. Watson, J.M.J.
Williams, Tetrahedron Lett. 51, 5804 (2010)
22. M. Hosseini-Sarvari, H. Sharghi, J. Org. Chem. 71, 6652 (2006)
23. J.G. Kim, D.K. Jang, Synlett 14, 2093 (2010)
24. J.G. Kim, D.K. Jang, Synlett 8, 1231 (2010)
25. S.H. Jung, J.H. Ahn, K.S. Park, J.K. Choi, Bull. Korean Chem. Soc. 23, 149 (2002)
26. M.R.M. Bhojegowd, A. Nizam, M.A. Pasha, Chin. J. Catal. 31, 518 (2010)
27. S. Wang, Z. Wang, Z. Zha, Dalton Trans. 9363 (2009)
28. J. Grunes, G.A. Somorjai, Chem. Commun. 2257 (2003)
29. D. Astruc, F. Lu, J.R. Aranzaes, Angew. Chem. Int. Ed. 44, 7852 (2005)
30. M.T. Reetz, G. Lohmer, Chem. Commun. 1921 (1996)
31. M.T. Reetz, E. Westermann, Angew. Chem. Int. Ed. 39, 165 (2000)
32. C. Ramarao, S.V. Ley, S.C. Smith, I.M. Shirley, N. DeAlmeida, Chem. Commun. 1132 (2002)
33. J.A. Gladysz, Pure Appl. Chem. 73, 1319 (2001)
34. J.A. Gladysz, Chem. Rev. 102, 3215 (2002)
´
´
´
´
35. B. Rivas, R. Lopez-Fonseca, C. Jimenez-Gonzalez, I. Jose, G.J. Ortiz, Catal. 281, 88 (2011)
36. X. Shi, S. Han, R.J. Sanedrin, F. Zhou, M. Selke, Chem. Mater. 14, 1897 (2002)
37. Q. Liu, L. Wang, M. Chen, Y. Cao, H. He, K. Fan, J. Catal. 263, 104 (2009)
38. S.A. Hosseini, D. Salari, A. Niaei, F. Deganello, G. Pantaleo, P.J. Hojati, Environ. Sci. Health Part A
Toxic/Hazard. Subst Environ. Eng. 46, 291 (2011)
39. U. Zavyalova, B. Nigrovski, K. Pollok, F. Langenhorst, B. Mu¨ller, P. Scholz, B. Ondruschka, Appl.
Catal. B 83, 221 (2008)
40. S.A. Hosseini, M.T. Sadeghi, A. Alemi, A. Niaei, D. Salari, L. Kafi, Chin. J. Catal. 31, 747 (2010)
41. X.W. Lou, D. Deng, J. Lee, J. Feng, L. Archer, Adv. Mater. 20, 258 (2008)
42. V.K. Das, R.R. Devi, P.K. Raul, A. Thakur, J. Green Chem. 14, 847 (2012)
43. S. Majumdar, J. De, J. Hossain, A. Basak, Tetrahedron Lett. 54, 262 (2013)
44. D. Habibi, M. Nasrollahzadeh, H. Sahebekhtiari, J. Mol. Catal. A Chem. 378, 148 (2013)
45. M.R.M. Bhojegowd, A. Nizam, M.A. Pasha, Chin. J. Catal. 31, 518 (2010)
123