a
Table 1 Aerobic oxidations of alcohols by Mn/HT-Ox catalyst
“Global Education and Research Center for Bio-Environmental
Chemistry” of Osaka University.
Conv. Yield
b
b
Entry Substrate
1
Product
Time (h) (%)
(%)
Notes and references
12
12
12
12
12
11
99
99
97
99
<1
99
99
97
99
<1
c
1 (a) R. A. Sheldon and J. K. Kochi, in: Metal-Catalyzed Oxidations
of Organic Compounds, Academic Press, New York, 1981; (b) A.
Corma, S. Iborra and A. Velty, Chem. Rev., 2007, 107, 2411–2502.
2 (a) D. G. Lee, in Encyclopedia of Reagents for Organic Synthesis, ed.
L. A. Paquette, Wiley, New York, 1995, 4274–4281; (b) D. Arndt,
Manganese Compounds as Oxidizing Agents in Organic Chemistry,
Open Court: La Salle, IL, 1981; (c) R. Stewart, in Oxidation in
Organic Chemistry Part A, ed. K. B. Wiberg, Academic Press, New
York, 1965, ch. 1.
2
3
4
5
d
e
f
6
>99 >99
7
10
>99 98
3
(a) A. Rezaeifard, M. Jafarpour, M. A. Nasseri and R. Haddad,
Helv. Chim. Acta, 2010, 93, 711–717; (b) B. Bahramian, V. Mirkhani,
M. Moghadam and A. H. Amin, Appl. Catal., A, 2006, 315, 52–57;
(
c) M. Bagherzadeh, Tetrahedron Lett., 2003, 44, 8943–8945.
8
9
11
16
>99 >99
>99 98
4
The Mn catalyst combined with O for oxidation of alcohols :(a) Q.
2
Tang, X. Huang, C. Wu, P. Zhao, Y. Chen and Y. Yang, Catal.
Commun., 2009, 10, 1122–1126; (b) Y. C. Son, V. D. Makwana, A. R.
Howell and S. L. Suib, Angew. Chem., Int. Ed., 2001, 40, 4280–4283;
(
c) T. Kimura, M. Fujita, H. Sohmiya and T. Ando, Bull. Chem. Soc.
Jpn., 1992, 65, 1149–1150.
1
1
0
1
8
99
99
90
82
5 (a) T. Mitsudome, A. Noujima, Y. Mikami, T. Mizugaki, K.
Jitsukawa and K. Kaneda, Angew. Chem., Int. Ed., 2010, 49, 5545–
5
548; (b) K. Ebitani, K. Motokura, K. Mori, T. Mizugaki and K.
Kaneda, J. Org. Chem., 2006, 71, 5440–5447; (c) M. J. Climent, A.
Corma, S. Iborra and A. Velty, J. Catal., 2004, 221, 474–482; (d) B.
M. Choudary, M. L. Kantam, A. Rahman, C. V. Reddy and K. K.
Rao, Angew. Chem., Int. Ed., 2001, 40, 763–766.
16
1
1
2
3
10
18
99
99
88
76
6 F. Cavani, F. Triffiro and A. Vaccari, Catal. Today, 1991, 11, 173–301.
7
8
As previously reported, the energy shift values of Mn K-edge XANES
directly correspond to the mean oxidation states: (a) T. Ressler, J.
Wong, J. Roos and I. L. Smith, Environ. Sci. Technol., 2000, 34,
9
50–958; (b) J. M. Ramallo-L o´ pez, E. J. Lede, F. G. Requejo, J. A.
Rodriguez, J-Y. Kim, R. Rosas-Salas and J. M. Dom ´ı nguez, J. Phys.
Chem. B, 2004, 108, 20005–20010; (c) N. M. D. Brown and J. B.
McMonagle, J. Chem. Soc., Faraday Trans. 1, 1984, 80, 589–597.
1
4
11
>99 >99
Extended X-ray absorption fine structure (EXAFS) studies showed
that Mn/HT-Ox had no peak at 1.9 A˚ from a Mn–O shell which
1
1
5
6
24
24
18
11
17
10
appeared in Mn/HT, and the magnitudes of two prominent peaks
attributed to Mn–O and Mn–Mn shells around 1–3 A˚ in Mn/HT-Ox
were greater than those in Mn/HT (Fig. 1S†). The inverse FT of these
two peaks around 1–3 A˚ was well fitted using a Mn–O bond (1.9 A˚ )
and a Mn–Mn bond (2.9 A˚ ) with coordination numbers (CN) of 6.0
and 3.6, respectively. The above results suggest that highly dispersed
planar manganese oxide clusters consisting of approximately seven
Mn atoms are formed on the surface of Mn/HT-Ox (Table 1S†).
(a) N. Singh and D. G. Lee, Org. Process Res. Dev., 2001, 5, 599–603;
a
Reaction conditions: Substrate (1 mmol), catalyst (Mn: 6 mol%),
◦
b
toluene (8 mL), O atmosphere, 100 C. Determined by GC using
an internal standard technique. Cycle 1. Cycle 2. Cycle 3. HT was
used as catalyst.
2
c d e f
9
(
b) A. J. Fatiadi, Synthesis, 1987, 85–127.
1
1
1
0 The addition of radical scavengers of galvinoxyl, 4-tert-
butylcatechol, and N-tert-butyl-a-phenylnitrone in the identified
reaction conditions inhibited the oxidation, suggesting that this
Mn/HT-Ox-catalyzed oxidation involves the radical path and may
proceed via a pathway similar to that proposed by Goldman: (a) I. M.
Goldman, J. Org. Chem., 1969, 34, 3289–3295. See ESI for details†.
1 To confirm whether the oxidation of alcohol occurred at the Mn
species on the hydrotalcite solid, the Mn/HT-Ox, in the case of the
aerobic oxidation of benzyl alcohol, was removed by filtration after
ca. 50% conversion of benzyl alcohol at the reaction temperature.
Further treatment of the filtrate under similar reaction conditions
did not afford any product.
Acknowledgements
This work was supported by a Grant-in-Aid for Scientific Re-
search and Scientific Research on Priority Areas (No. 18065016,
“
Chemistry of Concerto Catalysis”) from the Ministry of
Education, Culture, Sports, Science, and Technology of Japan.
We thank Dr Uruga, Dr Tanida, Dr Honma, Dr Taniguchi and
Dr Hirayama (SPring-8) for XAFS measurements and express
special thanks to the Global Center of Excellence Program
2 H. Firouzabadi and Z. Mostafavipoor, Bull. Chem. Soc. Jpn., 1983,
5
6, 914–917.
13 A. J. Fatiadi, Synthesis, 1976, 65–105.
2
144 | Green Chem., 2010, 12, 2142–2144
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