An efficient selective oxidation of alcohols with potassium permanganate adsorbed on aluminum silicate under solvent-free conditions and shaking

Article abstract of DOI:10.1007/s00706-006-0506-0

A new procedure for the selective oxidation of alcohols to the corresponding aldehydes and ketones with potassium permanganate supported on aluminum silicate at room temperature under solvent-free conditions and shaking is reported. Springer-Verlag 2006.

Full text of DOI:10.1007/s00706-006-0506-0

Monatshefte f €u r Chemie 137, 1071–1074 (2006)
DOI 10.1007/s00706-006-0506-0
An Efficient Selective Oxidation of Alcohols
with Potassium Permanganate Adsorbed
on Aluminum Silicate under Solvent-free
Conditions and Shaking
Ji-Dong Lou1 , Chun-Ling Gao , Li Li , and Zhi-Gang Fang
;ꢀ
2
3
1
1
College of Life Sciences, China Jiliang University, Hangzhou, Zhejiang, China
Center for Prostate Disease Research, Uniformed Service University
of Health Science, Bethesda, USA
2
3
Instituto Superior Tecnico, Lisboa, Portugal
Received November 17, 2005; accepted (revised) December 13, 2005
Published online August 3, 2006 # Springer-Verlag 2006
Summary. A new procedure for the selective oxidation of alcohols to the corresponding aldehydes
and ketones with potassium permanganate supported on aluminum silicate at room temperature under
solvent-free conditions and shaking is reported.
Keywords. Alcohols; Oxidation; Potassium permanganate; Solvent-free; Shaking.
Introduction
One of the most important reactions of alcohols, which have long been the objec-
tive of many research papers, is their oxidation to the corresponding carbonyl
compounds. Potassium permanganate-based reagents have been extensively used
in organic synthesis [1, 2]. The utility of permanganate reagents in the above oxi-
dative transformation is compromised due to their possible toxicity, cumbersome
preparation, and potential danger in terms of product isolation and waste disposal.
Furthermore, in the oxidation of alcohols only few permanganate-based reagents
have been applied in the selective oxidation of primary alcohols into the corre-
sponding aldehydes.
Introduction of reagents on solid support [3, 4] has circumvented some of these
problems and provided an attractive alternative in organic synthesis in view of the
selectivity and associated ease of manipulation. Therefore, a number of perman-
ganate-based oxidants impregnated on solid support have been explored, however,
ꢀ Corresponding author. E-mail: lou@cjlu.edu.cn

1
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J.-D. Lou et al.
almost all of the described procedures are performed under heterogeneous condi-
tions, or are assisted by microwave irradiation.
Recently, considerable attention has been paid to solvent-free reactions [5]. They
are not only of interest from ecological point of view, but in many cases also offer
considerable synthetic advantages in terms of yield, selectivity, and simplicity of
the procedure. These factors are especially important in industry. Therefore, some
of the traditional organic synthesis methods, which have long been carried out in
solvents, may be modified to more modern, elegant, and safe versions.
Results and Discussion
We have described a new reagent, potassium permanganate supported on alumi-
num silicate, for the heterogeneous selective oxidation of alcohols [6]. In connec-
tion with this recent work [6] we now report here a novel and selective oxidation of
primary and secondary alcohols to the corresponding aldehydes and ketones using
this supported reagent under solvent-free conditions and shaking at room tempera-
ture without microwave irradiation (Scheme 1). A shaking machine is employed
for this reaction. We find that shaking is much more effective than using a stirrer
for this kind of solvent-free reactions. Some previous methods needed heat, but in
the present work heating is unnecessary and the reaction times are quite reduced.
The present method has manipulative advantages over previous heterogeneous
oxidations [6], e.g., the yields of the products are higher, the reaction conditions are
milder, and the work-up is easier. In addition, for selective oxidation testing, some
more sensitive functionalised substrates were investigated without causing any
problems (see Table 1). Furthermore, the important benefit of the present method
is that it needs no microwave irradiation, an extra energy. On the other hand, owing
to the reaction under solvent-free conditions, combustion, toxicity, and environ-
mental pollution of the solvents are reduced.
In the present procedure, the oxidant is first carefully added to the substrate and
then the mixture is shaken mechanically at room temperature. The progress of the
reaction is monitored by TLC. In general, the oxidations are completed within
60 min. The residue is then washed with dichloromethane or diethyl ether. Purifi-
cation of the residue gives a product that is of acceptable purity for most pur-
poses. As can be seen in Table 1, this method is generally applicable to a range
of alcohols, and gives the corresponding aldehydes and ketones in good yields.
Therefore, it compares favourably with some traditional KMnO -based oxidation
4
methods [2].
In conclusion, solvent free oxidation of primary and secondary alcohols using
KMnO supported on aluminum silicate at room temperature by shaking is a new
4
and efficient method for the preparation of the corresponding aldehydes and
ketones.
Scheme 1

An Efficient Selective Oxidation of Alcohols
1073
Table 1. Potassium permanganate supported on aluminum silicate oxidations by shaking
a
b
c
Substrate
Reaction time
min
Product
Yield
%
n–CH (CH ) CH OH
2
60
40
40
30
30
30
40
40
40
40
50
40
50
50
n–CH (CH ) CHO
3 2 4
81
93
97
97
95
3
2 4
CH CCl¼CHCH OH
CH CCl¼CHCHO
3
2
3
PhCH OH
2
PhCHO
PhCH¼CHCH OH
PhCH¼CHCHO
p–H CO–C H –CHO
2
p–H CO–C H –CH OH
3
6
4
2
3
6 4
d
CH ¼CHCH(OH)CH
CH ¼CHC(O)CH
90
2
3
2
3
CH CH CH(OH)CH
2
CH CH C(O)CH
3
93
97
98
93
89
93
89
90
3
3
3
2
Cyclohexanol
PhCH(OH)Ph
Cyclohexanone
PhC(O)Ph
PhCH(OH)COOC H
2
PhCOCOOC H
2 5
5
C H CH(OH)CH COOC H
1
C H COCH COOC H
15 31 2 2 5
5
31
2
2
5
PhCH(OH)CH OH
2
PhCOCH OH
2
Cycloproylmethanol
Dicycloproylmethanol
Cyclopropylformaldehyde
Dicycloproylketone
b
ꢂ
ꢂ
Product
bp= C=mmHg
mp= C of 2,4-DNP
Found
Reported [7]
Found
Reported [7]
n–CH (CH ) CHO
3 2 4
130–132=760
34–36=10
56–58=10
131
104–106
130–132
236–239
256–257
251–254
139–141
112–115
162
104
8
8
CH CCl¼CHCHO
145
178–179
248
129–130
3
PhCHO
237
255
PhCH¼CHCHO
120–122=10
121–123=10
p–H CO–C H –CHO
3 6 4
248
254
CH ¼CHC(O)CH
139.5–140.5
115
2
3
CH CH C(O)CH
3
77–80=760
152–155=760
115–118=0.9
125–129=10
80
155
3
2
Cyclohexanone
PhC(O)Ph
161–162
e
48–49
e
305
48–49
PhCOCOOC H
2
130=10
5
f
f
C H COCH COOC H
2 5
36–39
37–38
1
5
31
2
PhCOCH OH
2
111–113=10
107–109=760
60–63=10
118–120=11
97–100=740
162.5–163
232–234
184–186
191–194
233–236
182–185
193–194
Cyclopropylformaldehyde
Dicycloproylketone
a
b
All the substrates are commercially available; all the aldehydes and ketones have been described
previously and were identified by their IR spectra or by the IR spectra and melting points of their 2,4-
c
dinitrophenylhydrazones; yield of isolated product; isolated as the 2,4-dinitrophenylhydrazone;
d
e
f
mp of benzophenone; mp of ethyl 3-oxooctadecylate
Experimental
Oxidation of Benzyl Alcohol to Benzaldehyde; Typical Procedure
A mixture of 108 mg benzyl alcohol (1 mmol) and 2.3 g KMnO -aluminum silicate reagent [6] is
4
shaken mechanically (Horizontal oscillator, Model: HY-2, Zhengji Instrument Co. Ltd.) at room
temperature for 40 min. The progress of the reaction is monitored by TLC (plates: aluminum-
backed silica gel Merck 60 GF254) using n-hexane:ethyl acetate (8:2) as eluent. The reaction
3
mixture is then washed with 3 ꢁ 5 cm CH Cl . The combined filtrates are evaporated to give
2
2

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J.-D. Lou et al.: An Efficient Selective Oxidation of Alcohols
the crude product, which is purified by preparative TLC (n-hexane:ethyl acetate (8:2)) to afford
02 mg benzaldehyde (97%).
1
References
[
[
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[3] Laszlo P (1987) Preparative Chemistry Using Supported Reagents, Academic Press, San
Diego, CA
[
[
4] Mckillop A, Young DW (1979) Synthesis: 401; 481
5] For a more recent review of solvent-free oxidation of alcohols. In: Sineriz F, Thomassigny C,
Lou JD (eds) (2004) Curr Org Synth 1: 137
[6] Lou JD, Zhu LY, Wang LZ (2004) Monatsh Chem 135: 31
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