Efficient Oxidation of Alcohols with Potassium Permanganate Adsorbed on Aluminum Silicate Reagent

Article abstract of DOI:10.1007/s00706-003-0098-x

A new reagent, potassium permanganate adsorbed on aluminum silicate, suitable for the oxidation of primary and secondary alcohols to the corresponding carbonyl compounds is described.

Full text of DOI:10.1007/s00706-003-0098-x

Monatshefte f€ur Chemie 135, 31–34 (2004)
DOI 10.1007/s00706-003-0098-x
Efficient Oxidation of Alcohols
with Potassium Permanganate Adsorbed
on Aluminum Silicate Reagent
Ã
Ji-Dong Lou , Li-Yun Zhu, and Lan-Zhou Wang
College of Life Sciences, China Institute of Metrology, Hangzhou, Zhejiang 310034, China
Received July 29, 2003; accepted August 6, 2003
Published online November 10, 2003 # Springer-Verlag 2003
Summary. A new reagent, potassium permanganate adsorbed on aluminum silicate, suitable for the
oxidation of primary and secondary alcohols to the corresponding carbonyl compounds is described.
Keywords. Oxidation; Alcohols; Potassium permanganate; Aluminum silicate.
Introduction
The oxidation of alcohols to carbonyl compounds is an important reaction in
synthetic organic chemistry. Potassium permanganate (KMnO4), an oxidizing
agent used in organic chemistry for over a century, is one of the most versatile
and vigorous ones of the commonly used oxidants for the above transformation. It
is generally accepted that, in acidic, basic, or neutral media, permanganate ion
oxidizes primary alcohols to aldehydes or acids, and secondary alcohols to ketones
[1, 2].
The concept of utilizing reagents adsorbed on, or intercalated in, insoluble
inorganic supports for organic synthesis has been employed. Some important meth-
ods have been reviewed [3, 4]. The classical methods for the oxidation of alcohols
with KMnO4 have now also been supplemented by using solid supports, such as
molecular sieve [5], copper sulfate pentahydrate [6], bentonite [7], kieselguhr [8],
zeolite [9], and zirconyl chloride octahydrate [10]. These supported reagents have
achieved milder reaction conditions, simpler processing, and often higher selectiv-
ity. However, little of the above supported KMnO4 reagents, for instance, KMnO4-
molecular sieve, KMnO4-kieselguhr, and KMnO4-zirconyl chloride octahydrate
reagents, have been applied in the selective oxidation of primary alcohols to the
corresponding aldehydes, and the rest are used only for the oxidation of secondary
alcohols to ketones.
Ã
Corresponding author. E-mail: lou@cim.edu.cn

32
J.-D. Lou et al.
Results and Discussion
We now report that KMnO4 adsorbed on aluminum silicate is a new reagent suitable
for the selective oxidation of primary alcohols to the corresponding aldehydes, and it
also can successfully oxidize secondary alcohols to ketones (Scheme 1). Therefore it
compares favourably with those reagents reported only for oxidizing secondary alco-
hols. In addition, comparing with supported KMnO4 reagents oxidizing primary
alcohols, the present reagent has some extra advantages, such as shorter reaction
times than those using KMnO4-molecular sieve, KMnO4-kieselguhr, and KMnO4-
Scheme 1
Table 1. Oxidation of alcohols with KMnO4-aluminum silicate reagent
Substrate
Producta
Yieldb, c=%
90
97
94
97
95
85
96
96
a
All the aldehydes and ketones have been described previously in literature and were identified by
b
their IR spectra or by the IR spectra and melting points of their 2,4-dinitrophenylhydrazones; all
products were distilled with a short Vigreux column under reduced pressure; c in case the boiling point
of the products were higher than that of toluene, the work-up was according to procedure A; in case the
boiling point of the products were lower than that of toluene, the work-up was according to procedure
B (see Experimental)

Potassium Permanganate Adsorbed on Aluminum Silicate
33
zirconyl chloride octahydrate reagents, and higher yields than by using the KMnO4-
kieselguhr reagent. On the other hand, the present solid support is much cheaper than
molecular sieve and zirconyl chloride octahydrate. Thus the present work not only is a
new extension of reported supported KMnO4 reagents, but also offers special promise
for the oxidation of alcohols to the corresponding aldehydes or ketones with sup-
ported KMnO4 reagents.
The KMnO4-aluminum silicate reagent is prepared by addition of a weighed
amount of aluminum silicate to a solution of KMnO4 in water and evaporating to
dryness. After contacting of the alcohols with KMnO4-aluminum silicate reagent in
toluene and filtration of the reaction mixture, the corresponding aldehydes or ketones
are obtained by evaporation or distillation of the solvent. Further purification is
accomplished by distillation. The results, which are given in Table 1, show that the
reagent is generally applicable to a range of alcohols, and gives the corresponding
products in good yields. Meantime, we have observed that aliphatic alcohols such as
1-hexanol or 1-octyl alcohol are not efficiently oxidised under these conditions.
Experimental
Preparation of KMnO4-Aluminum Silicate Reagent
A 500 cm3 round-bottomed flask is charged with 150 cm3 of 0.1 M aqueous KMnO4 and 10g of
aluminum silicate is added to it in one portion. The flask is then transferred to a rotary evaporator
and water is removed under reduced pressure. The coated residues are separated physically and dried
under vacuum to afford about 12g of the KMnO4-aluminum silicate reagent.
Oxidation of Benzyl Alcohol to Benzaldehyde, Procedure A
The above reagent (700 mg) is placed in a flask together with 15cm3 of toluene and the mixture is
magnetically stirred. A solution of 32.4mg of benzyl alcohol (0.3mmol) in 3 cm3 of toluene is added
and after 30min at 70–80ꢀC the solid is filtered and washed with 3Â5 cm3 of toluene. The combined
filtrates are evaporated to give crude product, which is purified by distillation with a short Vigreux
column under reduced pressure to afford 31mg (97%) of benzaldehyde.
Oxidation of 2-Butanol to 2-Butanone, Procedure B
The above reagent (700 mg) is placed in a flask together with 15cm3 of toluene and the mixture is
magnetically stirred. A solution of 22 mg of 2-butanol (0.3mmol) in 2 cm3 of toluene is added and after
30min at 70–80ꢀC the solid is filtered off and washed with 3Â5 cm3 of toluene. The crude product is
distilled carefully from the combined filtrates, which is then purified by re-distillation with a short
Vigreux column under reduced pressure to give 18mg (85%) of 2-butanone.
Acknowledgements
Financial support from the China Institute of Metrology to J.-D. Lou is gratefully acknowledged.
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J.-D. Lou et al.: Potassium Permanganate Adsorbed on Aluminum Silicate
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