Reductive amination of aldehydes and ketones with sodium borohydride supported onto HZSM-5 zeolite under microwave irradiation in a solvent free system

Article abstract of DOI:10.1080/104265090902831

Sodium borohydride supported onto a HZSM-5 zeolite is presented as a general reducing agent for the reductive amination of aldehydes and ketones under microwave irradiation in solventless system. Copyright Taylor & Francis Inc.

Full text of DOI:10.1080/104265090902831

This article was downloaded by: [The University of Manchester Library]
On: 12 October 2014, At: 05:45
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
Phosphorus, Sulfur, and Silicon
and the Related Elements
Publication details, including instructions for
authors and subscription information:
http://www.tandfonline.com/loi/gpss20
Reductive Amination of
Aldehydes and Ketones with
Sodium Borohydride Supported
Onto HZSM-5 Zeolite Under
Microwave Irradiation in a
Solvent Free System
Hossein A. Oskooie a , Somaih Solemani Amiri a
Majid M. Heravi a & Mitra Ghassemzadeh b
,
a Department of Chemistry , School of Sciences,
Azzahra University , Vanak, Tehran, Iran
b Chemistry & Chemical Engineering Research Center
of Iran , Tehran, Iran
Published online: 19 Aug 2006.
To cite this article: Hossein A. Oskooie , Somaih Solemani Amiri , Majid M. Heravi
& Mitra Ghassemzadeh (2005) Reductive Amination of Aldehydes and Ketones with
Sodium Borohydride Supported Onto HZSM-5 Zeolite Under Microwave Irradiation in a
Solvent Free System, Phosphorus, Sulfur, and Silicon and the Related Elements, 180:9,
2047-2050, DOI: 10.1080/104265090902831
To link to this article: http://dx.doi.org/10.1080/104265090902831
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

Phosphorus, Sulfur, and Silicon, 180:2047–2050, 2005
Copyright © Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/104265090902831
Reductive Amination of Aldehydes and Ketones with
Sodium Borohydride Supported Onto HZSM-5 Zeolite
Under Microwave Irradiation in a Solvent Free System
Hossein A. Oskooie
Somaih Solemani Amiri
Majid M. Heravi
Department of Chemistry, School of Sciences, Azzahra University,
Vanak, Tehran, Iran
Mitra Ghassemzadeh
Chemistry & Chemical Engineering Research Center of Iran, Tehran,
Iran
Sodium borohydride supported onto a HZSM-5 zeolite is presented as a general re-
ducing agent for the reductive amination of aldehydes and ketones under microwave
irradiation in solventless system.
Keywords Reductive amination; sodium borohydride; solventless system; zeolite
The reaction of aldehydes or ketones with ammonia, primary amines
or secondary amines in the presence of reducing agents to give pri-
mary, secondary, or tertiary amines, respectively, known as reductive
aminations (of the carbonyl compounds) or reductive alkylations (of the
amines) are among the most useful and important tools in the synthesis
of different kinds of amines.1
There are two commonly used direct reductive amination methods.
The first method is catalytic hydrogenation with platinum, palladium
or nickel catalyst.2 Hydrogenation has limited use with compounds
containing carbon-carbon multiple bonds and in the presence of re-
ducible functional groups such as the nitro3 and cyano groups.4 The cat-
alyst may be inhibited by compounds containing divalent sulfur.5 The
second method utilizes hydride reducing agents, particularly sodium
cyanoborohydride (NaBH3CN)6 and sodium borohydride (NaBH4)7 for
Received September 24, 2004; accepted September 28, 2004.
Address correspondence to Hossein A. Oskooie, Azzahra University, Department of
Chemistry, School of Sciences, Vanak, Tehran, Iran. E-mail: mmh1331@yahoo.com
2047

2048
H. A. Oskooie et al.
reduction. The latter has been conducted in sulfuric acid medium. Con-
sequently, we thought it is worthwhile to develop a manipulatively easy
and eco-friendly method for the reduction of in-situ-generated Schiff’s
bases. In this article we wish to report that sodium borohydride sup-
ported onto HZSM-5 zeolite can be used effeciently for the reductive
amination of carbonyl compounds under microwave irradiation in a sol-
ventless system. The combination of supported reagents and microwave
irradiation has been used to carry out a wide range of reactions in short
times and with high conversions and selectivity without the need for
solvents among other advantages.8
The choice of solid support and linkage are important factors for suc-
cess in solid phase synthesis.9 Unlike solution phase synthesis where
an optimization study will result in reproducible reactions, time con-
suming validation steps, usually required in solid phase synthesis, may
only be specific for a particular solid support.10 In continuation of our
ongoing program using zeolites to develop environmentally benign sol-
ventless system,11 we present a comparative study of reaction rates,
yields, and purity in the reductive amination of aldehydes and ke-
tones with sodium borohydride to assess the effectiveness of a HZSM-5
zeolite.
A number of solid supports such as silica gel, clays (such as montmo-
rillonite K-10), HZ- and NaY zeolite and HZSM-5 zeolite were used for
the simplification of this reduction. We found that the choice of the solid
support is very critical to the success of reaction, since sodium borohy-
dride should reduce imines (or iminium ions) selectively over aldehydes
and ketones under the reaction conditions. We discovered among the
mentioned supports HZSM-5 zeolite afforded the best results.
The direct reductive amination reactions were carried out by a simple
mixing of the carbonyl compounds amine and HZSM-5 zeolite, irradiat-
ing this mixture in an unmodified household microwave. The progress
of the reaction is followed by TLC. After completion of the reaction,
10% NaBH4 in wet HZSM-5 was added and mixed thoroughly. This
mixture was placed in a microwave oven. The progress of reaction was
monitored by TLC. After the completion of reaction, CH2Cl2 was added.
The mixture was filtered and the filtrate was evaporated to dryness to
afford the products. The results from various reductive amination re-
actions of aldehydes and ketones are listed in Table I. The results in
Table I showed that the reductive amination of a wide variety of alde-
hydes and ketones with primary and secondary amines was successful
under this condition and gave the desired products in good to excellent
yields. In conclusion, results presented in this communication indicate
that sodium borohydride supported onto HZSM-5 zeolite is a syntheti-
cally useful reagent for reductive amination of aldehydes and ketones.

Reductive Amination of Aldehydes
2049
TABLE I Reduction of Carbonyl Compounds With Sodium
Borohydride Supported Onto HZSM-5 Zeolite Under Microwave
Irradiation in Solventless System
Entry Carbonyl compound
Amine
Timea (min) Yieldb (%)
1
2
3
4
5
6
7
8
9
Benzaldehyde
Benzaldehyde
Benzaldehyde
Salicylaldehyde
Salicylaldehyde
Acetophenone
Acetophenone
Cyclohexanone
4-Methylcyclohexanone
Aniline
9
10
10
5
7
5
5
5
5
87
81
85
95
93
95
71
87
85
Ethylamine
Propylamine
Aniline
4-methylaniline
Aniline
Benzylamine
Aniline
Aniline
aTime for reduction on in situ generated Schiff bases in MW over.
bYields reported are those of pure isolated products.
Sodium borohydride is a mild, commercially available reagent. When
it is mixed with wet HZSM-5 zeolite, it can be used under microwave
irradiation for the fast reaction and solventless system for the sake of
an environmentally friendly condition.
EXPERIMENTAL
All compounds are known and were identified by comparison with au-
thentic samples (physical and spectroscopic data). Yields refer to iso-
lated products purified by column chromatography. For safety reasons,
all the experiments with microwave ovens should be performed in an
efficient hood to avoid contact with vapors.
REDUCTIVE AMINATION OF SALICYLALDEHYDE WITH
4-METHYLANILINE
A Typical Procedure
A mixture of 4-methylaniline (0.107 g, 1 mmol) and HZSM-5 zeolite
(0.02 g) was thoroughly grinded using a pestle and mortar. To this mix-
ture salicylaldehyde was added in a beaker. The beaker was placed in a
microwave oven and irradiated for 2 min. The in-situ-generated Schiff’s

2050
H. A. Oskooie et al.
base was mixed thoroughly with freshly prepared NaBH4-HZSM-5
zeolite (0.038 g, 1 mmol NaBH4 on 0.334 g zeolite) and water (1 mL).
The reaction mixture was again irradiated for 5 min. The progress of
reaction was monitored by TLC. Upon completion of the reaction, the
product was extracted by CH2Cl2. The removal of solvent and crystal-
lization from EtOH afforded the product in a 93% yield.
REFERENCES
[1] A. F. Abdel-Majid, K. G. Carson, B. D. Harris, C. A. Maryanoff, and R. D. Shoh,
J. Org. Chem., 61, 3849 (1996).
[2] (a) W. S. Emerson, Org. React. 4, 174 (1948) and references cited therein; (b) W. S.
Emerson and C. A. Uraneck, J. Am. Chem. Soc., 63, 749 (1941); (c) H. E. Jahnson
and D. G. Crosly, J. Org. Chem., 27, 2205 (1962); (d) M. V. Klyver and M. L. Khidekel,
Russ. Chem. Rev., 49, 14 (1980).
[3] N. Rylander, In Catalytic Hydrogenation over Platinum Metals, New York: Academic
Press, p. 128 (1967).
[4] Ibid, 128.
[5] Ibid, 21.
[6] (a) C. F. Lane, Synthesis, 135 (1975); (b) B. N. Trost and I. Fleming, In Comprehensive
Organic Synthesis, 1 ed., New York: Pergamon Press, vol. 8 (1991).
[7] V. Giancarlo, A. G. Giumanini, P. Strazzolini, and M. Poiana, Synthesis, 121 (1993).
[8] R. S. Varma, Green Chemistry, 43 (1999) and references cited therein.
[9] W. Li and B. Yan, J. Org. Chem., 63, 4092 (1998).
[10] K. Bergers and D. Lim, Chem. Commun., 785 (1997).
[11] M. M. Heravi and M. Ghassemzadeh, Phosphorus, Sulfur, and Silicon, 178, 119
(2003) and references cited therein.