Catalysis Communications
Short Communication
One pot catalytic NO2 reduction, ring hydrogenation, and N-alkylation
from nitroarenes to generate alicyclic amines using Ru/C-NaNO2
Seung Geun Oh a,b,1, Vivek Mishra b,1, Jin Ku Cho b, Baek-Jin Kim b, Hoon Sik Kim c, Young-Woong Suh d,
Hyunjoo Lee e, Ho Seok Park a, Yong Jin Kim b,
⁎
a
Department of Chemical Engineering, College of Engineering, Kyung Hee University, Gyeonggi-do 446-701, Republic of Korea
Green Process Material Research Group, Korea Institute of Industrial Technology, Chungcheongnam-do 331-822, Republic of Korea
Department of Chemistry and Research Institute of Basic Sciences, Kyung Hee University, Seoul 130-701, Republic of Korea
Department of Chemical Engineering, Hanyang University, Seoul 133-791, Republic of Korea
b
c
d
e
Clean Energy Center, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 20 July 2013
Received in revised form 11 September 2013
Accepted 12 September 2013
Available online 20 September 2013
A report to produce alicyclic amines and subsequent N-alkylation with alcohols using Ru/C-NaNO2 catalyzed fac-
ile transformation of nitrobenzene was investigated. Effects of solvent, temperature, pressure, reaction time, and
molar-ratio of substrate/catalyst on product composition were also studied. These mechanistic studies explain
that nitrobenzene undergoes hydrogenation reaction in the following order; –NO2 reduction to –NH2, aromatic
ring-hydrogenation to alicyclic, and from the reaction of alcohol to give N-alkylated amines. This investigation
shed lights on possible application to polyurethane chemistry since these amines are used as important precur-
sors for diisocyanates.
Keywords:
Hydrogenation
Nitrobenzene
© 2013 Elsevier B.V. All rights reserved.
Cyclohexylamine
Ruthenium catalyst
1. Introduction
of aromatic amines due to its high activity, selectivity, and reproducibil-
ity [10–13]. The N-alkylation of amines using non-halide reagent is also
The efficient synthetic pathway for producing amines has been
extensively investigated due to the fact that they are widely used as
significant intermediate as well as final product in various chemical
industries [1,2]. Especially, the cyclohexylamine (CHA) finds various
applications in pharmacology or as agrochemicals in terms of its being
raw material for carbamates and isocyanates. Among these, alicyclic
diamines also more substantially used feedstock for the synthesis of
non-yellowing polyurethanes.
Conventionally, the CHA has been produced from the following
two step; i) reduction of nitrobenzene (NB) to aniline [3–9], ii) ring hy-
drogenation of aniline to CHA [1,2,10–13], which makes the process
complicated. Therefore, development of a facile one step synthetic path-
way to alicyclic amines from nitroarenes is of great importance with
respect to process efficacy.
an important process because conventional halogenated substances
may generate harmful by-products such as HCl [15–17]. To overcome dis-
advantages, alcohols can be employed as direct alkylating agent for the N-
alkylation of amines [18–21]. Since there has been no report on one-pot
synthesis of CHA or N-alkylated amines from the reaction of NB with H2
and alcohols, this approach might provide much greener pathway from
the view point of process efficiency as well as cost saving.
In this context, a direct synthesis of alicyclic amines and their subse-
quent production of N-alkylated amines from the reaction of nitroarenes
with H2 and alcohols in the presence of a catalyst system comprising
carbon supported Ru and NaNO2 are presented.
2. Experimental
As to the industrial processes to manufacture aniline through NB hy-
drogenation, the process generally employs above 240 °C with copper-
catalysts in two-stage bed reactor [14]. Recently, Langer et al. reported
a low-pressure process for the hydrogenation of aniline to produce
CHA with high selectivity using rhodium catalysts [11]. The literature in-
dicates that ruthenium is the most used catalyst for ring-hydrogenation
All the chemicals and catalyst were purchased from Aldrich (South
Korea) and used without further purification.
2.1. Hydrogenation reaction
All the hydrogenation reactions were carried out in a 100 ml pres-
surized reactor with a magnetic stirrer and an electrical heater (Fig. 1).
Detailed procedure of hydrogenation reactions is given in supporting
information.
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Corresponding author. Tel.:+82 415898469; fax: +82 415898580.
These authors contributed equally to this work.
1
1566-7367/$ – see front matter © 2013 Elsevier B.V. All rights reserved.