A convenient one-pot method of converting alcohols into oximes

Article abstract of DOI:10.1080/10426500490466535

The one-pot conversion of primary and secondary alcohols into oximes is reported using chromium trioxide supported on alumina and hydroxylamine hydrochloride under solvent free condition. This oxidation-oxime formation reaction has been applied to a range of aliphatic and benzylic alcohols.

Full text of DOI:10.1080/10426500490466535

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Phosphorus, Sulfur, and Silicon and the Related
Elements
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A CONVENIENT ONE-POT METHOD OF CONVERTING
ALCOHOLS INTO OXIMES
Ali Reza Kiasat a , Foad Kazemi a & Kazem Nourbakhsh a
a Chemistry Department, College of Science, Shahid Chamran University , Ahvaz, Iran
Published online: 16 Aug 2010.
To cite this article: Ali Reza Kiasat , Foad Kazemi & Kazem Nourbakhsh (2004) A CONVENIENT ONE-POT METHOD OF
CONVERTING ALCOHOLS INTO OXIMES, Phosphorus, Sulfur, and Silicon and the Related Elements, 179:9, 1809-1812, DOI:
10.1080/10426500490466535
To link to this article: http://dx.doi.org/10.1080/10426500490466535
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Phosphorus, Sulfur, and Silicon, 179:1809–1812, 2004
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Copyright Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426500490466535
A CONVENIENT ONE-POT METHOD OF
CONVERTING ALCOHOLS INTO OXIMES
Ali Reza Kiasat, Foad Kazemi, and Kazem Nourbakhsh
Chemistry Department, College of Science,
Shahid Chamran University, Ahvaz, Iran
(Received January 22, 2004)
The one-pot conversion of primary and secondary alcohols into oximes
is reported using chromium trioxide supported on alumina and hydrox-
ylamine hydrochloride under solvent free condition. This oxidation-
oxime formation reaction has been applied to a range of aliphatic and
benzylic alcohols.
Keywords: Alcohols; chromium trioxide; oximes; hydroxylamine
hydrochloride; solvent free
In organic syntheses and reactions, increasing attention is be-
ing focused on solvent-free procedures,1 which often lead to clean,
eco-friendly, and highly efficient procedures involving simplified
workup.2
The “ideal synthesis” of functionalized compounds requires the de-
velopment of one-pot successive reactions from commercially available
and cheap starting materials and/or catalysts.3 Recently in a series of
relevant papers Taylor and coworkers developed a number of syntheti-
cally useful tandem oxidation processes, such as conversion of primary
alcohols to alkenes,4 imines,5 amines,5 oxime ethers,6 esters,7 amides7
and nitriles.8 One of the main benefits of this methodology is the in situ
formation and consumption of the intermediate aldehydes.
The remarkable ability of the alumina to promote the various re-
actions under solvent-free conditions9 together with the importance
of combinatorial chemistry as a preparative technique in organic
synthesis10 gave us impetus for testing the oxidation of primary and
We acknowledge the partial support of this work by Shahid Chamran Ahvaz Univer-
sity Research Council.
Address correspondence to Ali Reza Kiasat, Chemistry Department, College of Sci-
ence, Shahid Chamran University, Ahvaz 6137-4-3169, Iran.
1809

1810
A. R. Kiasat et al.
FIGURE 1
secondary alcohols followed by in situ protection of the resulting
carbonyl compounds as oximes in an one-pot process using chromium
trioxide supported on alumina and hydroxylamine hydrochloride under
solvent-free conditions.
Chromium trioxide supported on alumina was prepared by simply
cogrinding alumina with CrO3 in the ratio 10:1 (w/w) in an agate mor-
tar. In this simple and efficient method, when the starting alcohol and
two molar equivalent of CrO3/Al2O3 and a few drops of t-BuOH were
mixed with grinding by a pestle, alcohol was consumed (TLC) within
10 min to furnish a carbonyl compound as the only product of the oxida-
tion step. This reaction was followed by in situ trapping of the resulting
carbonyl compound by an additional elimination reaction. For this pro-
pose, the reaction mixture was ground with ten molar equivalent of
hydroxylamine hydrochloride (7 min).
As reported in Table I, satisfactory results have been obtained in
the oxidation-oxime formation reaction of a variety of primary and
secondary alcohols with CrO3/Al2O3 and NH2OHHCl under solvent-
free conditions. The tolerance of various functional groups under the
present reaction conditions have been examined by reacting the sub-
strates bearing phenolic hydroxy, ether, nitro, and olefinic double-bond
groups. The structure of all the products was established from their
analytical and spectral infrared (IR), 1H NMR, data and by direct com-
parison with authentic samples.
This one-pot methodology avoids the need to isolate the intermedi-
ate carbonyl compounds, a particularly useful feature in the case of
carbonyl compounds, which are volatile, toxic, or highly reactive. It can
be emphasized that the reaction is clean, the workup is straightfor-
ward, and from economical and environmental points of view use of
solvent-free conditions is favorable.
In conclusion, we have demonstrated a rapid and solvent-free method
for one-pot conversion of alcohols to oximes. We believe that the
present procedure provides easy, mild, efficient, versatile, and general
methodology for the oxidation-oxime formation of different classes of
alcohols.

Oximes
1811
TABLE I One-Pot Preparation of Oximes by Treatment of Alcohols with
CrO3/Al2O3 and NH2OHHCl
Entry
1
Substrate
Product
Yielda,b (%)
80
2
3
4
89
80
87
5
6
68
75
7
8
9
81
79
71
10
90
11
12
83
91
aYields refer to pure isolated products.
bProducts were characterized by comparsion of their physical data, and IR and NMR
spectra, with known samples.
General Experimental Procedure for the Conversion
of Alcohols to Oximes
A mortar was charged with Al2O3 (2 g) and CrO3 (0.2 g, 2 mmol); the
mixture was ground with a pestle for 1 min. Then alcohols (1 mmol)
and several drops of t-butanol were added to the mixture. The reaction
mixture was ground for about 10 min. NH2OHHCl (0.69 g, 10 mmol) was
added to the mixture and ground for 7 min. The progress of reaction was

1812
A. R. Kiasat et al.
monitored by TLC using ether-CCl4. After the disappearance of starting
material, the reaction mixture was mixed with ether. The mixture was
filtered to remove alumina and then mixed with water and extracted.
The organic layer was dried over Na2SO4. The solvent was removed in
vaccuo to give the product.
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[4] L. Blackburn, C. Pei, and R. J. K. Taylor, Synlett, 215 (2002).
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