Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.
G.S. Nunes et al. / Journal of Catalysis 260 (2008) 188–192
191
IV,IV,III
+
+
.
Scheme 2. Cyclohexane oxidation catalyzed by the oxo species [Ru3O(H3CCO2)6(py)2O] , or [Ru3
=O]
Table 4
hol, or by the reaction of the intermediate radical 2-cyclohexen-1-
yl with the oxygen donor species.
Effect of the oxygen donor agent in the oxidation of the cyclohexane catalyzed by
[Ru3O(H3CCO2)6(py)2(CH3OH)]PF6.a
The methanol and dmso complexes also catalyse the oxidation
of cyclohexane by TBHP and PhIO by means of the cleavage of the
C–H bond followed by oxygen atom transfer, rather than by the
alternative oxygen radical mechanism characteristic of this type of
complexes.
Oxygen
donor
Cyclohexanol
Cyclohexanone
%
Ratio
ol:ona
b
%
TON
TON
TBHPc
PhIOd
3.2 ( 0.2)
7.7 ( 0.4)
2.7 ( 0.1)
6.9 ( 0.4)
2.4 ( 0.1)
16.7 ( 0.8)
1.9 ( 0.1)
15.1 (0.7)
1.4 ( 0.1)
0.46 (0.03)
a
−6
2.68 × 10
mol of cluster, t = 2 h.
b
c
Acknowledgments
Based on the starting oxygen donor amount.
Catalyst:oxygen donor:cyclohexane mol ratio = 1:83:746.
Catalyst:oxygen donor:cyclohexane mol ratio = 1:74:746.
d
The support from Fundação de Amparo a Pesquisa do Estado
de São Paulo, Conselho Nacional de Desenvolvimento Científico e
Tecnológico, and Instituto do Milenio de Materiais Complexos, is
gratefully acknowledged.
a similar way observed for porphyrins (Scheme 2) [25–33]. Forma-
tion of cyclohexanone can be explained by the oxidation of the
cyclohexanol product or by the reaction of the cyclohexyl radi-
cal formed near the catalytic site, with the oxygen donor. In the
presence of the radical scavenger CCl4, cyclohexyl can also react to
form chlorocyclohexane [34–36]. As a matter of fact, this pathway
has been detected, as shown in Table 3.
References
[1] B. Meunier, S.P. de Visser, S. Shaik, Chem. Ver. 104 (2004) 3947.
[2] M.H.V. Huynh, T.J. Meyer, Chem. Rev. 107 (2007) 5004.
[3] M.M. Abu-Omar, A. Loaiza, N. Hontzeas, Chem. Rev. 105 (2005) 2227.
[4] J.T. Groves, J. Inorg. Biochem. 100 (2006) 434.
[5] D. Chatterjee, A. Mitra, R.E. Shepherd, Inorg. Chim. Acta 357 (2004) 980.
[6] T. Okumura, Y. Morishima, H. Shiozaki, T. Yagyu, Y. Funahashi, T. Ozawa, K. Jit-
sukawa, H. Masuda, Bull. Chem. Soc. Jpn. 80 (2007) 507.
[7] Y. Miyazaki, A. Satake, Y. Kobuke, J. Mol. Catal. A Chem. 283 (2008) 129.
[8] D. Chatterjee, A. Mitra, J. Mol. Catal. A 282 (2008) 124.
[9] Z.W. Yang, Q.X. Kang, F. Quan, Z.Q. Lei, J. Mol. Catal. A Chem. 261 (2007) 190.
[10] B. Meunier, Chem. Rev. 92 (1992) 1411.
The kinetics of the cluster catalyzed oxidation of cyclohexane by
tert-butyl hydroperoxide have been investigated. A typical result,
expressed by the plot of product concentration (ol + one) versus
time, is illustrated in Fig. 3. From the linear plot of ln[P∞ − P]
(where P∞ is the final total concentration of products) versus
−6 −1
time, a first order kinetic constant of 7.7 0.5 × 10
s
(R =
0.998) has been obtained in this case.
In Table 4 one can compare the yields of cyclohexane oxidation
for the two oxygen donors. The results show that iodosylbenzene is
more efficient than tert-butyl hydroperoxide, being able to activate
the catalyst in a higher number of cycles, but yielding predomi-
nantly cyclohexanone.
[11] T.J. Meyer, M.H.V. Huynh, Inorg. Chem. 42 (2003) 8140.
[12] V.R. de Souza, G.S. Nunes, R.C. Rocha, H.E. Toma, Inorg. Chim. Acta 348 (2003)
50.
[13] H.E. Toma, K. Araki, A.D.P. Alexiou, S. Nikolaou, S. Dovidauskas, Coord. Chem.
Rev. 219–221 (2001) 225.
[14] S. Davis, R.S. Drago, J. Chem. Soc. Chem. Commun. (1990) 250.
[15] C. Bilgrien, S. Davis, R.S. Drago, J. Am. Chem. Soc. 109 (1987) 3786.
[16] G.L. Tembe, P.A. Ganeshpure, React. Kinet. Catal. Lett. 67 (1999) 83.
[17] G.S. Nunes, A.D.P. Alexiou, K. Araki, A.L.B. Formiga, R.C. Rocha, H.E. Toma, Eur.
J. Inorg. Chem. (2006) 1487.
4. Conclusions
The [Ru3O(H3CCO2)6(py)2(L)]PF6 clusters where L = methanol,
dimethyl sulfoxide, can be activated by peroxide or oxygen donor
species, such as tert-butyl hydroperoxide or iodosylbenzene, re-
spectively, generating reactive intermediates of the type
[18] A.D.P. Alexiou, H.E. Toma, J. Chem. Res. (S) (1993) 464.
[19] H.E. Toma, C.J. Cunha, C. Cipriano, Inorg. Chim. Acta 154 (1988) 63.
[20] H.J. Lucas, E.R. Kennedy, M.W. Formo, Org. Synth. Coll. 3 (1955) 483.
[21] J.G. Sharefkin, H. Saltzmann, Org. Synth. 43 (1963) 62.
[22] K. Jitsukawa, Y. Oka, S. Yamaguchi, H. Masuda, Inorg. Chem. 43 (2004) 8119.
[23] A. Morvillo, M. Bressan, J. Mol. Catal. A Chem. 125 (1997) 119.
[24] L.K. Stultz, M.H.V. Huynh, R.A. Binstead, M. Curry, T.J. Meyer, J. Am. Chem.
Soc. 122 (2000) 5984.
[25] T. Naota, H. Takaya, S.-I. Murahashi, Chem. Ver. 98 (1998) 2599.
[26] W.P. Griffith, Chem. Soc. Rev. 21 (1992) 179.
[27] G.A. Barf, R.A. Sheldon, J. Mol. Catal. A Chem. 102 (1995) 23.
[28] J. Bernadou, B. Meunier, Chem. Commun. (1998) 2167.
[29] C.-C. Guo, H.-P Li, J.-B. Xu, J. Catal. 185 (1999) 345.
[RuI3V,IV,III=O] . This species preferentially reacts with the C=C
+
bond in cyclohexene, producing the epoxide in high yields, and
also is able to abstract a hydrogen atom from the C–H bond, form-
ing the radical 2-cyclohexen-1-yl, in an intermediate step, before it
is converted into the corresponding alcohol. The formation of the
2-cyclohexen-1-one in significant amount can be explained by a
ruthenium-catalyzed oxidative dehydrogenation of the allylic alco-