Studies in Beckmann rearrangement of substituted benzophenone and acetophenone oximes

Article abstract of DOI:10.1081/SCC-120004081

The Beckmann rearrangement of substituted benzophenone and acetophenone oximes was effected using 'silferc' as catalyst, prepared by impregnating anhydrous FeCl₃ on silica gel by co-grinding technique.

Full text of DOI:10.1081/SCC-120004081

This article was downloaded by: [Heriot-Watt University]
On: 07 March 2015, At: 14:52
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,
37-41 Mortimer Street, London W1T 3JH, UK
Synthetic Communications: An International Journal
for Rapid Communication of Synthetic Organic
Chemistry
Publication details, including instructions for authors and subscription information:
http://www.tandfonline.com/loi/lsyc20
STUDIES IN BECKMANN REARRANGEMENT OF
SUBSTITUTED BENZOPHENONE AND ACETOPHENONE
OXIMES
Bhushan M. Khadilkar a & Dharita J. Upadhyaya b
a Applied Organic Chemistry Laboratory , University Department of Chemical Technology ,
University of Mumbai , Matunga, Mumbai, 400 019, India
b Applied Organic Chemistry Laboratory , University Department of Chemical Technology ,
University of Mumbai , Matunga, Mumbai, 400 019, India
Published online: 17 Oct 2011.
To cite this article: Bhushan M. Khadilkar & Dharita J. Upadhyaya (2002) STUDIES IN BECKMANN REARRANGEMENT OF
SUBSTITUTED BENZOPHENONE AND ACETOPHENONE OXIMES, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 32:12, 1867-1873, DOI: 10.1081/SCC-120004081
To link to this article: http://dx.doi.org/10.1081/SCC-120004081
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the information (the “Content”) contained
in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no
representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the
Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and
should be independently verified with primary sources of information. Taylor and Francis shall not be liable for
any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever
or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of
the Content.
This article may be used for research, teaching, and private study purposes. Any substantial or systematic
reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any
form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at http://
www.tandfonline.com/page/terms-and-conditions

MARCEL DEKKER, INC. • 270 MADISON AVENUE • NEW YORK, NY 10016
©2002 Marcel Dekker, Inc. All rights reserved. This material may not be used or reproduced in any form without the express written permission of Marcel Dekker, Inc.
SYNTHETIC COMMUNICATIONS, 32(12), 1867–1873 (2002)
STUDIES IN BECKMANN
REARRANGEMENT OF
SUBSTITUTED BENZOPHENONE
AND ACETOPHENONE OXIMES
*
Bhushan M. Khadilkar and Dharita J. Upadhyaya
Applied Organic Chemistry Laboratory, University
Department of Chemical Technology, University of
Mumbai, Matunga, Mumbai 400 019, India
ABSTRACT
The Beckmann rearrangement of substituted benzophenone
and acetophenone oximes was effected using ‘silferc’ as cata-
lyst, prepared by impregnating anhydrous FeCl3 on silica gel
by co-grinding technique.
The acid-mediated isomerization of oximes to amides or what is known
as ‘Beckmann reaction’ has been extensively explored in the recent years.[1]
Besides its high commercial utility for the production of caprolactam, the
reaction is also of academic interest due to the case with which it effects
nitrogen insertion into the carbon framework. Various reagents used to med-
iate the rearrangement includes concentrated H2SO4,[2] PCl5,[3] HF,[4] P2O5-
methanesulphonic acid,[5] AlCl3 and polyphosphoric acid.[7] The results
[6]
obtained by these reagents are usually good, but the toxic by-products
*Corresponding author. E-mail: dharita_bmk@aplchem.udct.ernet.in
1867
Copyright & 2002 by Marcel Dekker, Inc.
www.dekker.com

MARCEL DEKKER, INC. • 270 MADISON AVENUE • NEW YORK, NY 10016
©2002 Marcel Dekker, Inc. All rights reserved. This material may not be used or reproduced in any form without the express written permission of Marcel Dekker, Inc.
1868
KHADILKAR AND UPADHYAYA
generated from these reagents have prompted increasing interest in the devel-
opment of alternative, more environmentally benign catalysts.
Recently, this reaction has been studied by various solid acid catalysts
such as metal oxides, clay[8] and zeolites[9]. However, most of these reactions
are under vapor-phase conditions and in liquid phase they proceed in rather
sluggish manner. The preparation procedures for these catalysts often involve
various tedious steps such as precipitation, ion exchange, acid–alkali treat-
ment, hydrothermal treatment and prolonged activation time at higher tem-
peratures. Also, with catalysts such as zeolites, reproducibility is still a
problem. Due to our interest in the field of heterogeneous catalysts, we
have developed novel catalytic materials by co-grinding technique.[10] By
this method, an active species can be uniformly dispersed on the metal
oxide support by co-grinding the two together. Various moisture-sensitive
reagents such as AlCl3, FeCl3,[10] ZnCl2,[10] CrO3
[11]
have been effectively
stabilized without losing their activity by supporting them on metal oxide
support. The method ensures uniform dispersion and the catalysts prepared
by this technique have been characterized by SEM-EDAX, XRD, DRIFT
and other techniques. The SEM-EDAX results offer evidence of uniform
dispersion of active reagent on the surface. The method also avoids the use
of excessive volatile fire vulnerable solvents that are otherwise used for the
impregnation thereby offering a ‘Greener alternative’. Exploring the utility of
this material, we describe in this paper, the studies carried out in Beckmann
rearrangement of substituted benzophenone and acetophenone oximes con-
taining various activating as well as deactivating groups using ‘silferc’ (anhy-
drous FeCl3 supported on silica-gel by co-grinding method) in liquid phase.
In case of substituted benzophenone oximes, the rearrangement pre-
dominates over Beckmann fragmentation, thus giving the corresponding
benzanilides in very high yields (Table 1). The reaction conditions are
Scheme 1.

MARCEL DEKKER, INC. • 270 MADISON AVENUE • NEW YORK, NY 10016
©2002 Marcel Dekker, Inc. All rights reserved. This material may not be used or reproduced in any form without the express written permission of Marcel Dekker, Inc.
STUDIES IN BECKMANN REARRANGEMENT
1869

MARCEL DEKKER, INC. • 270 MADISON AVENUE • NEW YORK, NY 10016
©2002 Marcel Dekker, Inc. All rights reserved. This material may not be used or reproduced in any form without the express written permission of Marcel Dekker, Inc.
1870
KHADILKAR AND UPADHYAYA
Scheme 2.
Table 2. Optimized Results of Beckmann Rearrangement of Substituted
Acetophenone Oximes
Isolated Yields (%)
M.P. (ꢀC) (6)
Reaction
Time (h)
Entry
5 (R)
6
7
Observed Reported
1
2
3
4
5
H
CH3
OCH3
3,4-Dimethyl
Cl
5
5
5
5
5
21
39
58
604098
–
79
61
42
114
144–6
132
115
146
130–2
99
10
0
–
–
very mild and the amount of catalyst used is also catalytic. The solvent
played a very important role in directing the course of the reaction. It was
observed that when the reactions are carried out in boiling EDC, rearrange-
ment predominates whereas in boiling toluene, fragmentation leading to the
corresponding ketone took place.
In case of substituted acetophenone oximes, it was seen that rearran-
gement and deoximation both occurred simultaneously (Table 2). A detailed
study revealed a marked dependence of the course of reaction on the nature
of substituent. Electron releasing groups like CH3, OCH3 and 3,4-dimethyl
(Entries 2,3,4) increased the nucleophilicity of substrate and hence the extent
of rearrangement. Whereas, groups like Cl decreases the nucelophilicity of
the ring and thus favored deoximation. The method permits preparation of
‘Methacetin’ (Entry 3) that is an antineuralgic and antipyretic agent in good
yield (58%) under relatively milder conditions as compared to convention-
ally used hazardous reagents. In case of substituted acetophenone oximes,
carrying out the reaction in boiling toluene brings about deoximation.
In conclusion, we have reported Beckmann rearrangement of substi-
tuted benzophenone and acetophenone oximes using ‘silferc’ under milder
conditions. The catalyst could effectively bring about the rearrangement of

MARCEL DEKKER, INC. • 270 MADISON AVENUE • NEW YORK, NY 10016
©2002 Marcel Dekker, Inc. All rights reserved. This material may not be used or reproduced in any form without the express written permission of Marcel Dekker, Inc.
STUDIES IN BECKMANN REARRANGEMENT
1871
substituted benzophenone oximes in catalytic amount and it also gave
reusability for atleast one run. Although the yields of corresponding rear-
rangement product in case of substituted acetophenone oximes are low, the
method eliminates the use of various hazardous reagents which are other-
wise used to bring about the reaction, thereby reducing the amount of toxic
by-products generated at the end of the process.
EXPERIMENTAL
Catalyst Preparation
The catalyst (silferc) was prepared by co-grinding FeCl3 and silica gel
(SRL 230–400 mesh) in appropriate amounts in an agate mortar and acti-
vating it at 90ꢀC for 3 h to obtain yellow free flowing powder. The
catalyst was stored in an airtight bottle and was activated at 90ꢀC for 3 h
prior to use.
Beckmann Rearrangement(General Procedure)
A mixture of the ketoximes (5 mM) and Silferc[18] (2.5 gm, FeCl3 con-
tent, 0.4 gm, 3 mM) was stirred in 1,2-dichloroethane at its reflux tempera-
ture. The reaction was monitored by TLC. The mixture was filtered hot and
the catalyst was washed three times with 20ml portion of boiling EDC. The
excessive solvent was distilled off to give anilide, which was purified by
column chromatography (4 Pet ether : 1 Ethylacetate).
ACKNOWLEDGMENT
The authors are thankful to G. D. Gokhale trust for awarding fellow-
ship to one of the authors.
REFERENCES
1. Gawley, R.E. Org. React. 1988, 35, 1.
2. Gregory, Barrie J.; Moodie, Roy B.; Schofield, Kenneth. Kinetics and
Mechanism of the Beckmann Rearrangement of Acetophenone Oximes
in Sulfuric Acid. J. Chem. Soc. B 1970, 2, 338–46.

MARCEL DEKKER, INC. • 270 MADISON AVENUE • NEW YORK, NY 10016
©2002 Marcel Dekker, Inc. All rights reserved. This material may not be used or reproduced in any form without the express written permission of Marcel Dekker, Inc.
1872
KHADILKAR AND UPADHYAYA
3. Babiyan, N.A.; Smolina, G.A.; Mndzhoyan, O.L. Beckmann Rearran-
gement of p-Alkoxybenzophenone Oximes. Arm. Khim. Zh. 1971,
24(4), 345–9.
4. Kopple, K.D.; Katz, J.J. Beckmann Rearrangement in Hydrogen
Fluoride. J. Org. Chem. 1959, 24, 1975–77.
5. Eaton, P.E.; Carlson, G.R.; Lee, J.T. Phosphorus Pentoxide-Methane-
sulfonic Acid. A Convenient Alternative to Polyphosphoric Acid.
J. Org. Chem. 1973, 38, 4071.
6. Ghiaci, M.; Immazadeh, Hassan G. A Facile Beckmann Rearrange-
ment of Oximes with AlCl3 in the Solid State. Synth. Commun. 1998,
28(12), 2275.
7. Guy, Alain; Guette, Jean paul; Lang, Gerard. Utilization of Polypho-
sphoric Acid in the Presence of a Cosolvent. Synthesis 1980, 3, 222–3.
8. (a) Meshram, H.M. Clay Catalyzed Facile Beckmann Rearrangement
of Ketoxides. Synth. Commun. 1990, 20, 3253; (b) Pai, S.G.; Bajpai,
A.R.; Deshpande, A.B.; Samant, S.D. Beckmann Rearrangement of
Substituted Diaryl Ketoximes Using FeCl3 Impregnated Montmorillo-
nite K10. Synth. Commun. 1997, 27(3), 379–84.
9. (a) Kath, Holger; Glaser, Roger; Weitkamp, Jens. Beckmann Rearran-
gement of Cyclohexanone Oxime on MFI-type Zeolites. Chem. Eng.
Technol. 2001, 24, 2; (b) Camblor, M.A.; Corma, A.; Garquimica,
U. P.V. C.S. I.C. Active Sites for the Liquid-Phase Beckmann Rear-
rangement of Cyclohexanone, Acetophenone and Cyclododecanone
Oximes Catalyzed by Beta Zeolites. J. Catal. 1998, 177(2), 267–72.
10. Khadilkar, B.M.; Borkar, S.D. Environmentally Clean Synthesis
of Diphenylmethanes Using Silica Gel Supported ZnCl2 and FeCl3.
J. Chem. Technol. Biotechnol. 1998, 71(3), 209.
11. Bendale, P.M.; Khadilkar, B.M. Microwave Promoted Regeneration
of Carbonyl Compounds from Oximes Using Silica Supported
Chromium Trioxide. Tetrahedron Letters 1998, 39, 5867–68.
12. Dictionary of Organic Compounds, 6th Ed.; Chapman & Hall: London,
1996; Vol. 5, p. 4248 & 4221.
13. Dictionary of Organic Compounds, 6th Ed.; Chapman & Hall: London,
1996; Vol. 5, p. 4192.
14. Fahmy, A.F.M.; Hosni, G.; Fadeel, A.H. Synthesis and Reactions of
O-Aryl Carbamoyl Diaryl Ketones. Indian J. of Chemistry 1976, 14B,
871–73.
15. Dictionary of Organic Compounds, 6th Ed.; Chapman & Hall: London,
1996; Vol. 2, p. 1280.
16. Alberghina, G.; Fisichella, S. Kinetics of the Reactions of Some 3- &
5-Substituted 2-Thenoyl and ortho- and para-Benzoyl Chloride with
Aniline in Benzene. J. Chem. Soc., Perkin Trans. 2 1978, 81–4.

MARCEL DEKKER, INC. • 270 MADISON AVENUE • NEW YORK, NY 10016
©2002 Marcel Dekker, Inc. All rights reserved. This material may not be used or reproduced in any form without the express written permission of Marcel Dekker, Inc.
STUDIES IN BECKMANN REARRANGEMENT
1873
17. Dictionary of Organic Compounds, 6th Ed.; Chapman & Hall: London,
1996; Vol. 2, p. 929.
18. In case of substituted acetophenone oximes, FeCl3 content in the given
catalysts was equimolar to that of corresponding oxime.
Justification: The Beckmann rearrangement of substituted benzo-
phenone and acetophenone oximes was effectively studied by using a
novel catalyst prepared by co-grinding technique. The catalyst preparation
eliminates the use of volatile organic solvents, which are used for impreg-
nation thereby offering a ‘Greener alternative’. The reactions were carried
out under milder conditions, the amount of catalyst required was catalytic
and also showed reusability.
Received in the Netherlands June 20, 2001