An Efficien t Nitr a tion of Ligh t Alk a n es a n d th e Alk yl Sid e-Ch a in
of Ar om a tic Com p ou n d s w ith Nitr ogen Dioxid e a n d Nitr ic Acid
Ca ta lyzed by N-Hyd r oxyp h th a lim id e
Yoshiki Nishiwaki, Satoshi Sakaguchi, and Yasutaka Ishii*
Department of Applied Chemistry, Faculty of Engineering, Kansai University, Suita,
Osaka 564-8680, J apan
ishii@ipcku.kansai-u.ac.jp
Received February 20, 2002
Nitration of light alkanes and the alkyl side-chain of aromatic compounds with NO2 and HNO3
was successfully achieved by the use of N-hydroxyphthalimide (NHPI) as a catalyst under relatively
mild conditions. For example, the nitration of propane with NO2 catalyzed by NHPI at 100 °C for
14 h gave 2-nitropropane in good yield without formation of 1-nitropropane and cleaved products
such as nitroethane and nitromethane. Various aliphatic nitroalkanes, which are difficult to prepare
by conventional methods, could be selectively obtained by means of the present methodology by
using NHPI as the key catalyst. In addition, the side-chain nitration of alkylbenzenes such as toluene
was selectively carried out to lead to R-nitrotoluene without the ring nitration. The present reaction
provides an efficient selective method for the nitration of light alkanes and alkylbenzenes, which
has been very difficult to carry out so far.
In tr od u ction
such as oxygen, ozone, or halogen have been made, these
additives promote not only the generation of alkyl
radicals but also the production of oxygenated or halo-
genated compounds.2 For the nitration of adamantanes,
several methods have been developed so far. Olah et al.
have shown the nitration with nitronium salts in ni-
tromethane.4 Photoinduced nitration with N2O5 is re-
ported to produce an approximately 1:1 mixture of
nitroadamantane and adamantane nitrite.5 Recently,
Suzuki et al. have presented a novel nitration using NO2
assisted by ozone,6 although this strategy is limited to
the nitration of adamantane and its derivatives. Hence,
a new general strategy for the nitration of alkanes with
NO2 has been desired for a long time, in particular, in
the chemical industry.
Nitration of saturated hydrocarbons is a fundamental
and important reaction in synthetic and industrial
organic chemistry.1 Despite their practical importance,
however, useful methods for the nitration of aliphatic
hydrocarbons have been rarely developed in contrast to
the nitration of aromatic hydrocarbons. Currently, nitra-
tion of light alkanes by nitrogen dioxide or nitric acid as
a nitrating reagent is operated at higher reaction tem-
perature (200-350 °C) to generate thermally alkyl
radicals by the C-H bond scission of alkanes.2 The
reaction under such forced conditions, however, would
cause undesired C-C bond scissions, since the bond
dissociation energy of the C-C bonds of alkanes is rather
lower than that of the C-H bonds. Therefore, the large-
scale nitration of alkanes has been limited to several
lower alkanes such as methane, ethane, and propane. For
example, it has been reported that the nitration of
propane with NO2 at 300 °C produces 1- and 2-nitropro-
panes along with cleaved nitro compounds such as
nitroethane and nitromethane in 26% total yield based
on NO2 used.3 Although attempts to improve the conver-
sion and selectivity to nitroalkanes by adding an additive
In the course of our studies on the development of
aerobic oxidation of alkanes catalyzed by N-hydroxy-
phthalimide (NHPI),7 we have recently disclosed in
communications8 a practical and versatile catalytic method
for the nitration of cyclohexane and adamantane with
NO2 or HNO3 in the presence of NHPI . In this paper,
we wish to report our recent results for the selective
nitration of light alkanes and the alkyl side-chain of
aromatic compounds by NO2 or HNO3 with NHPI as a
key catalyst.
(1) Ono, N. The Nitro Group in Organic Synthesis; Wiley-VCH: New
York, 2001.
(2) (a) Albright, F. L. Chem. Eng. 1966, 73, 149. (b) Albright, L. F.
In Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed.;
Kroschwite, J . I., Howe-Grant, M., Eds.; J ohn Wiley and Sons: New
York, 1995; Vol. 17, p 68. (c) Markofsky, S. B. In Ullmann’s Encyclo-
pedia Industrial Organic Chemicals; Wiley-VCH: Weinheim, Germany,
1999; Vol. 6, p 3487.
(3) (a) Bachman, G. G.; Hass, B. H.; Addison, M. L. J . Org. Chem.
1952, 17, 914. (b) Bachman, G. G.; Hass, B. H.; Addison, M. L. J . Org.
Chem. 1952, 17, 928. (c) Bachman, G. G.; Hewett, V. J .; Millikan, A.
J . Org. Chem. 1952, 17, 935. (d) Bachman, G. G.; Kohn, L. J . Org.
Chem. 1952, 17, 942.
(4) (a) Olah, G. A.; Lin, C. H. J . Am. Chem. Soc. 1971, 93, 1259. (b)
Olah, G. A.; Ramaish, P.; Rao, C. B.; Sandfold, G.; Golam, R.; Trivedi,
N. J .; Olah, J . A. J . Am. Chem. Soc. 1993, 115, 7246.
(5) Tabushi, I.; Kojo, S.; Yoshida, Z. Chem. Lett. 1971, 1431.
(6) Suzuki, H.; Nonomiya, N. Chem. Commun. 1996, 1783.
(7) Ishii, Y.; Sakaguchi, S.; Iwahama, T. Adv. Synth. Catal. 2001,
343, 393.
(8) (a) Sakaguchi, S.; Nishiwaki, Y.; Kitamura, T.; Ishii, Y. Angew.
Chem. Int. Ed. 2001, 40, 222. (b) Isozaki, S.; Nishiwaki, Y.; Sakaguchi,
S.; Ishii, Y. Chem. Commun. 2001, 1352.
10.1021/jo025632d CCC: $22.00 © 2002 American Chemical Society
Published on Web 06/26/2002
J . Org. Chem. 2002, 67, 5663-5668
5663