Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 2, pp. 338−340.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © A.V. Logvinov, S.F. Melnikova, A.A. Astrat’ev, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 2, pp. 342−344.
Cyclohexanol Nitration by a Mixture of Ammonium Nitrate
and Sulfuric Acid in a Two-Phase System
A. V. Logvinov, S. F. Melnikova, and A. A. Astrat’ev
St. Petersburg State Technological Institute, St. Petersburg, Russia
Federal State Unitary Enterprise “Technologist” Special Engineering and Technological Bureau,
St. Petersburg, Russia
Received June 21, 2010
Abstract—Cyclohexanol nitration by a mixture of ammonium nitrate and sulfuric acid in the presence of an organic
solvent was studied.
Cyclohexyl nitrate (CHN) is an effective addition
agent raising a cetane number of diesel fuel . One of
promising methods of CHN synthesis is the cyclohexanol
nitration by a mixture of sulfuric and nitric acids, however
it requires lower temperatures (–20…–30°С) owing to
the tendency of cyclohexanol and CHN to be oxidized
by nitric acid [2, 3].
It is known that the application of nitrating mixtures
with increased water contents or of mixtures based on
nitric acid salts allows the temperature of cyclohexanol
nitration to be increased up to 5–10°С [4, 5]. However,
as a result of side processes a hazard of an uncontrollable
decomposition of the waste acid mixture accompanied by
heat and gas release increases. The use of an inert organic
solvent in the cyclohexanol nitration by a sulfuric-nitric
mixture makes it possible to increase the CHN yield and
the admissible temperature of the process up to 10–15°С,
but in this case the probability of the decomposition of
the acid layer remains, which demands its fast separation
and neutralization [6, 7]. The uncontrollable heat effect
gives rise to a hazard of exceeding the process critical
temperature and thus can result in contingency situations
connected with equipment decompression, ejection of
a reaction mass, and complete product loss.
It was found that the application of an ammonium
nitrate and sulfuric acid mixture in combination with
addition of an inert solvent makes it possible to increase
the yield of a reaction product and to raise considerably
stability of the waste acid mixture. Conditions and results
of the experiments are given in the table; the nitrating
mixture composition is speciﬁ ed without taking into ac-
count formed ammonium bisulfate.
For comparison we used solutions of ammonium ni-
trate (experiments nos. 1–6) and nitric acid (experiments
nos. 7, 8) in sulfuric acid, taking methylene chloride as
an inert solvent. The highest yield was reached for the
nitrating mixture containing 3.5% of water at the nitration
temperature of 10–11°С (experiment no. 4). Decrease
in sulfuric acid concentration (experiment no. 5) or in
ammonium nitrate excess (experiment no. 6), and also
the absence of the organic solvent cause uncontrollable
heat release while an alcohol dosing, which hinders the
reaction completion. The composition of the nitrating
mixture obtained when nitric acid was used (experiments
nos. 7, 8) was selected as optimal on the basis of a series
of previous experiments.
Stability of the waste acid mixture after separation of
layers was estimated by varying its temperature during
holding in equal conditionals without effective cooling.
The results obtained are shown in the ﬁ gure.
As follows from the ﬁ gure, when ammonium nitrate
is used instead of nitric acid, exhausted nitro mixture