1070-4272/01/7411-1877$25.00C2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 11, 2001, pp. 1877!1879. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 11,
2001, pp. 1819!1821.
Original Russian Text Copyright + 2001 by F. Sharikov, Yu. Sharikov, Belokhvostov, Veretennikov, Lebedev, Tselinskii.
PROCESSES AND EQUIPMENT
OF CHEMICAL INDUSTRY
A Calorimetric Study of the Kinetics of Chlorobenzene
Mononitration with Nitric Acid
F. Yu. Sharikov, Yu. V. Sharikov, V. M. Belokhvostov, E. A. Veretennikov,
B. A. Lebedev, and I. V. Tselinskii
Prikladnaya Khimiya Russian Scientific Center, St. Petersburg, Russia
St. Petersburg State Technological Institute, St. Petersburg, Russia
Received January 26, 2001
Abstract-The calorimetric method was applied to study the kinetics of chlorobenzene mononitration with
74.9 and 95.8% nitric acid and a kinetic model of the process was developed. A comparison of the thermo-
dynamic parameters of nitration led to a conclusion concerning the limiting stage of the reaction.
The basic method for obtaining nitrochlorobenzene
is nitration of chlorobenzene with a mixture of sul-
furic and nitric acids. A specific feature of this tech-
nique is that it produces large amounts of dilute
sulfuric acid whose regeneration cannot prevent at
present its detrimental environmental effects.
To eliminate this shortcoming, it has been pro-
posed to use for obtaining aromatic nitro compounds
solely nitric acid as nitrating agent . In , nitra-
tion of chlorobenzene with 68397% nitric acid was
studied and two versions of a procedure for producing
nitrochlorobenzene with 75 and 95% nitric acid used
for nitration were developed. These methods gave
nitrochlorobenzene in nearly quantitative yield. The
process was carried out in a cascade of two 60 cm
continuous reactors. To solve the problem of whether
these results could be reproduced on industrial scale,
it is necessary to develop a mathematical model of the
process and study the possible choice of optimal and
safe conditions under which the process can be per-
formed in industrial nitration reactors.
The kinetics of the process was studied using the
calorimetric method with a heat-flow calorimeter
which makes it possible to obtain, together with data
on the process kinetics, necessary information about
the heat effect and thermal properties of the reaction
mixture. As starting conditions were chosen those
under which chlorobenzene is nitrated with 75 and
95% nitric acid .
Chlorobenzene containing 99.0% main substance
and 98% nitric acid were used in kinetic experiments.
Prior to being used, nitric acid was distilled in a vacu-
um from a mixture with sulfuric acid and diluted at
0oC with distilled water to a prescribed concentration.
The acid concentration was determined by alkalimet-
ric titration. Deionized water was used to evaluate the
thermal effects and relative rates of hydration.
The reaction kinetics were studied on a C-80 Se-
taram automated heat-flow calorimeter in special two-
chamber chromium3nickel ampules. Nitric acid was
placed in the bottom chamber and, after weighing,
the necessary amount of chlorobenzene in the upper
chamber was calculated. Prior to the reaction, the
reactants were separated with a high-strength fluoro-
plastic film, which is stable against the action of
corrosive media. A hermetically sealed ampule was
placed in the sensitive zone of the calorimeter. At
the beginning of an experiment the membrane was
ruptured with a special-purpose rod stirrer and the
components were subjected to primary agitation.
Further agitation in the course of the experiment was
provided by 180o rotation of the calorimetric unit
together with the ampule fixed in it. After the experi-
ment was complete, the reaction mass was diluted
with water to nitric acid concentration of 35340% and
extracted with chloroform; the extract was washed
with water and analyzed by gas3liquid chromatogra-
phy. The yield and isomeric composition of the nitra-
tion product were in agreement with the data reported
in . The analytically obtained chlorobenzene con-
versions corresponded to the values found from the
heat-release curve in each experimental series.
The C-80 calorimeter is automated with the use of
an IBM-compatible computer and an appropriate inter-
face. The experiments were carried out, experimental