'Zeofen', a user-friendly oxidizing reagent

Article abstract of DOI:10.1039/a900087i

A variety of alcohols are oxidized to the corresponding carbonyl compounds in excellent yields by zeofen under classical heating and microwave irradiation in solventless system.

Full text of DOI:10.1039/a900087i

‘Zeofen’, a user-friendly oxidizing reagent
Majid M. Heravi,* Dariush Ajami, Kuoumars Aghapoor and Mitra Ghassemzadeh
Chemistry and Chemical Engineering Research Center of Iran, PO Box 14335-186, Tehran, Iran.
E-mail: ccerci@neda.net
Received (in Cambridge, UK) 4th January 1999, Accepted 26th March 1999
A variety of alcohols are oxidized to the corresponding
carbonyl compounds in excellent yields by zeofen under
classical heating and microwave irradiation in solventless
system.
the completion of the reactions (monitored by TLC) the reagent
was filtered off and washed with CH Cl . Evaporation of
2
2
solvent gave the corresponding carbonyl compounds. It should
be pointed out that in the absence of zeolite, the reaction was
sluggish and even at reflux temperature a considerable amount
of starting material was recovered unchanged. Different types
of alcohols were converted to their corresponding carbonyl
compounds by this procedure in high yields. The results are
presented in Table 1.
Oxidation of alcohols to carbonyl compounds is a fundamental
transformation in organic synthesis and, because of its sig-
nificant role, the development of newer methods is attracting
much current interest1 in spite of the availability of numerous
–4
5,6
methods reported in the literature. The use of heavy metals
and peracids is very common.7 However, a drawback of such
oxidants and their use in multistage organic synthesis in spite of
their power is their lack of selectivity. For instance, over-
Although there has been growing interest in applying
,8
23
microwave dielecteric heating to accelerate organic reactions,
oxidation reactions are less often considered as candidates for
microwave irradiation due to their unsafe and uncontrollable
9
24
oxidation of aldehydes to carboxylic acids and degradation of
experimental conditions. It has been shown that polar
unsaturated substrates are often unavoidable side reactions.10 In
addition to their lack of selectivity, oxidants based on
reactants adsorbed on the surface of solid supports absorb
microwaves.25 In connection with our interest in using micro-
11
12
19
chromium and manganese are corrosive, irritants and
waves to increase the rates of reactions, we have investigated
toxic.13
the above oxidation under microwave irradiation. The oxidation
reactions were carried out simply by mixing 1–1.2 equiv. of
zeofen with 1 equiv. of an alcohol in a beaker under microwave
irradiation (900 W) for 2 min. For example, benzyl alcohol was
oxidized to benzaldehyde in almost quantitative yields after
10 s. It is noteworthy to mention that in the absence of zeolite,
the reaction was slow and, more seriously, molten ferric nitrate
and/or its degradation product(s) adhered to the walls of the
reaction vessel, forming an intractable solid mass which made
the isolation of carbonyl compounds difficult and led to erratic
results. Indeed when iron(iii) nitrate was used without zeolite
the conversion of benzyl alcohol to benzaldehyde was only 50%
under conditions otherwise similar to those described above.
Clearly zeolite aided the reproducibility and high activity of
iron(iii) nitrate. To assess the generality of this oxidation a
variety of alcohols were reacted under these conditions, which
yielded the corresponding carbonyl compounds in excellent
yields. Table 2 summarizes the data for oxidation of alcohols
under microwave irradiation in a solventless system.
In view of economic, practical and recent environmental
demands,14 we saw significant advantage in using a non-toxic
and inexpensive metal salts such as iron(iii) nitrate. Some early
success in the use of clayfen for oxidation of alcohols15
supported this idea.
Reagents impregnated on mineral supports have gained
popularity in organic synthesis because of their selectivity and
1
6,17
ease of manipulation.
Recently we reported the use of
18
zeolite catalyzed and microwave enhanced chemical reac-
tions19 on organic solid supports. We report here a facile
oxidation of alcohols to carbonyl compounds using zeofen
20
[
2 2
short for zeolite HZSM-5 supported iron(iii) nitrate] in CH Cl
at room temperature and under microwave irradiation in a
solventless system.
3 3 2
To prepare zeofen, Fe(NO ) .9H O (0.80 g, 2 mmol) and a
21
weight equivalent of HZSM-5 zeolite were crushed together
so as to form an intimate mixture (zeofen). This new reagent can
be stored in a dark brown bottle and is stable without suffering
from the problem of slow decomposition that clayfen does.22 In
a typical reaction 1–1.2 equiv. of zeofen was added to a stirring
In conclusion, zeofen can be easily prepared from inex-
pensive and non-toxic materials and serves as an excellent
oxidizing agent for various types of alcohols at room tem-
2 2
solution of an alcohol in dry CH Cl at room temperature. After
a
2 2
Table 1 Oxidation of alcohols to carbonyl compounds by zeofen in CH Cl
R1
R1
zeofen
CH2Cl2 or microwave
R2
OR
O
R2
H
b
Alcohol
t/min
Product
Yield (%)
1
2
3
4
5
6
7
8
9
0
PhCH
4-MeC
2-NO -5-MeC
(dl)-PhCH(Me)OH
Ph CHOH
PhCHNCHCH
PhCH CH(Ph)OH
Cyclohexanol
2
OH
20
20
20
30
40
40
40
60
60
60
PhCHO
4-MeC
2-NO -5-MeC
PhCO(Me)
Ph CO
PhCHNCHCHO
PhCH COPh
cyclohexanone
99 (90)
93 (88)
92 (85)
89 (80)
90 (82)
77 (67)
91 (88)
82 (78)
85 (76)
c
H
6 4
CH
2
OH
CH
6 4
H
CHO
c
2
6
H
3
2
OH
2
6
H
3
CHO
2
2
2
OH
2
2
c
c
2-Methylcyclohexanol
(2)-Menthol
2-methylcyclohexanone
menthone
1
85 (78)
a
. The physical data of the isolated products are in agreement with those of authentic samples. b Yields
Reaction using 1–1.2 equiv. of zeofen in CH
2
Cl
2
c
are based on GLC analysis. Figures in parenthesis are yields of isolated products. Yields based on isolation of the 2,4-DNPH derivative.
Chem. Commun., 1999, 833–834
833

Table 2 Oxidation of alcohols using zeofen under microwave irradiation in
a solventless system
6 A. J. Fatiadi, in Organic Synthesis by Oxidation with Metal Compounds,
ed. W. J. Mijs and C. R. H. I. de Jonge, Plenum, New York, 1986, pp.
a
1
19–260.
Yieldb
(%)
7 J. Einhorn, C. Einhorn, F. Ralajczak and J. L. Piere, J. Org. Chem.,
1996, 61, 7452.
Alcohol
t/s
10
20
OH 20
30
Product
PhCHO
8
J. Mazart, A. N. Ait Aijou and S. Ait-Mohand, Tetrahedron Lett., 1994,
39, 1989.
1
2
3
4
5
6
7
8
9
PhCH
4-MeC
2-NO -5-MeC
(dl)-PhCH(Me)OH
Ph CHOH
PhCHNCHCH
PhCH CH(Ph)OH
Cyclohexanol
2-Methylcyclohexanol
2
OH
99 (92)
97 (88)
CHO 95 (82)
90 (82)
c
c
6
H
4
CH
2
OH
CH
4-MeC
2-NO -5-MeC
PhCO(Me)
Ph CO
PhCHNCHCHO
PhCH COPh
cyclohexanone
6
H
4
CHO
9 M. M. Heravi, D. Ajami and K. Tabar-Hydar, Monatsh. Chem., 1998,
129, 1305.
2
6
H
3
2
2
6
H
3
10 M. M. Heravi, D. Ajami, K. Tabar-Hydar and M. M. Mojtahedi,
J. Chem. Res. (S), 1998, 620.
2
20
60
60
120
120
120
2
92 (80)
81 (87)
91 (88)
85 (81)
2
OH
11 B. J. Page and G. W. Loar, in Kirk-Othmer Encyclopedia of Chemical
Technology, 4th edn., Wiley, New York, 1998, vol. 6, pp. 263–311.
12 A. H. Reidies, in Kirk-Othmer Encyclopedia of Chemical Technology,
3rd edn., Wiley, New York, 1981, vol. 14, pp. 844–895.
13 Chromium in the Natural and Human Environments, ed. J. O. Nriagn
and E. Nieboer, Wiley, New York, 1988.
2
2
c
c
2-methylcyclohexanone 84 (78)
menthone 88 (80)
1
a
0 (2)-Menthol
Reaction using 1–1.2 equiv. of zeofen under microwave irradiation in a
solventless system. The physical data of the isolated products were in
agreement with those of authentic samples. Yields are based on GLC
analysis. Figures in parentheses are yields of isolated products. Yields
1
4 Chemistry of Waste Minimization, ed. J. H. Clark, Chapman and Hall,
b
London, 1995.
c
15 R. S. Varma and R. Dehija, Tetrahedron Lett., 1997, 38, 2043.
1
1
6 A. McKillop and D. W. Young, Synthesis, 1979, 401 and 481.
7 M. Balogh and P. Lazlo, Organic Chemistry using Clays, Springer
Verlag, Berlin, 1993.
based on isolation of the 2,4-DNPH derivative.
1
8 M. M. Heravi, M. Tajbakhsh, S. Y. Beheshtiha and H. A. Oskooie,
Indian J. Heterocyclic Chem., 1996, 6, 143; M. M. Heravi, H. A.
Oskooie and M. Mafi, Synth. Commun., 1997, 27, 1725; M. M. Heravi,
M. Tajbakhsh and B. Mohajerani, Synth. Commun., 1999, 29, 135.
9 M. M. Heravi, K. Aghapoor, M. A. Nooshabadi and M. M. Mojtahedi,
Monatsh. Chem., 1997, 128, 1143; K. Aghapoor, M. M. Heravi and
M. A. Nooshabadi, 1998, 37B, 84.
0 M. M. Heravi, R. Kiakoojori and K. Tabar-Hydar, J. Chem. Res., 1998,
656; M. M. Heravi, D. Ajami and K. Tabar-Hydar, Synth. Commun.,
1999, 29, 163; M. M. Heravi, D. Ajami, M. M. Mojtahedi and M.
Ghassemzadeh, Tetrahedron Lett., 1999, 40, 561.
perature in solvent and under solvent-free conditions using a
house-hold microwave oven. Solvent-free microwave irradia-
tion has an advantage over conventional heating, offering a
practical and environmentally benign protocol, decreasing
reaction time and in some cases giving cleaner reactions and
easier work up.
1
2
Research supported by the National Research Council of Iran
NRCI) as a National Research project under grant number
(
3708.
2
4
1 HZSM-5 zeolite was prepared by calcination of NH ZSM5 zeolite at
5
00 °C for 8 h. Si:Al = 40:1 and pore diameters are 5.1 3 55 Å. We
are grateful to Dr A. R. Garakani for a gift of zeolite.
2
2
2 A. Cornilis and P. Lazlo, Synthesis, 1985, 909.
Notes and references
3 R. A. Abramovitch, Org. Prep. Proced. Int., 1991, 23, 683; S. Cadadick,
Tetrahedron, 1995, 51, 10 403; C. R. Strauss and R. W. Trainer, Aust. J.
Chem., 1995, 48, 1665.
1
2
I. Delaude and P. Lazlo, J. Org. Chem., 1996, 61, 6360.
R. S. Varma, R. K. Saini and R. Dahuja, Tetrahedron Lett., 1997, 38,
7
823.
G. Sh. Zhang, Cr. Z. Shi, M. F. Chen and K. Cai, Synth. Commun., 1997,
7, 3691.
24 R. Gedye, F. Smith, K. Weslaway, A. Humera, L. Baldisera and L. R.
Laberge, Tetrahedron Lett., 1986, 26, 279.
25 R. S. Varma, R. Dahija and R. K. Saini, Tetrahedron Lett., 1997, 38,
7029 and references from this group cited therein.
3
2
4
5
R. S. Varma and R. K. Saini, Tetrahedron Lett., 1998, 39, 1481.
Comprehensive Organic Synthesis (Oxidation), ed. B. M. Trost,
Pergamon, New York, 1991, vol. 7.
Communication 9/00087I
834
Chem. Commun., 1999, 833–834