Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 2, pp. 172−176.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © M.V. Savos’kin, A.P. Yaroshenko, R.D. Mysyk, V.I. Shologon, S.V. Khripunov, S.A. Grebenyuk, I.E. Nosyrev, L.A. Prokof’eva, 2012,
published in Zhurnal Prikladnoi Khimii, 2012, Vol. 85, No. 2, pp. 182−187.
AND INDUSTRIAL INORGANIC CHEMISTRY
The Synthesis of Thermally Expandable Residual Graphite
Nitrate in the System HNO
M. V. Savos’kin, A. P. Yaroshenko, R. D. Mysyk, V. I. Shologon,
S. V. Khripunov, S. A. Grebenyuk, I. E. Nosyrev, and L. A. Prokof’eva
Litvinenko Institute of Physical-Organic Chemistry and Coal Chemistry,
National Academy of Sciences of Ukraine, Donetsk, Ukraine
Received March 31, 2010
Abstract—Effect exerted by the synthesis conditions of residual graphite nitrate in the system concentrated nitric
acid-glacial acetic acid-water on the properties of the ﬁ nal product was studied in wide consumption range of the
reagents. The optimal ratio of the reagents was determined. The dependence of expansion coefﬁ cient on the loss
of mass by the expanded product was determined.
Graphite intercalation compounds (GICs) and their
products are widely used in industry for producing
expansion ﬁ re protective coatings, paints, packers, ﬁ re
extinguishing compositions, ﬁ re proof polymeric com-
positions, and insulating compounds and mixtures .
The most signiﬁ cant drawback for the industrial use of
acceptor-type GICs is their low stability in atmospheric
conditions, including even ordinary temperatures. There-
fore, in practice there are used so-called “residual” com-
pounds  obtained by water treatment of starting GIC
and their subsequent drying. Some residual compounds
are thermally stable, but their structure is largely unclear.
Residual GICs obtained by water treatment of graphite
bisulfate are traditional industrial compounds . GICs
based on graphite nitrate have lower corrosion activity
 and expansion temperature than residual graphite bi-
sulfate, which causes a considerable interest in their use.
Graphite nitrate may be obtained by contact of graph-
ite with nitric acid by the Forsman scheme :
+ m HNO
where n is the number of the GIC stage and m, the number
of neutral acid molecules intercalated as ligand.
As seen from the given scheme, the presence of
water shifts the nitric acid self-ionization equilibrium
to the left impeding formation of nitronium cations. As
known, nitric acid containing about 5–8% water does
not virtually contain NO
particles. Consequently, this
scheme of obtaining graphite nitrate requires the use of
only concentrated nitric acid (~98%).
The water treatment of graphite nitrate, contrary to
graphite bisulfate, yields a residual compound , which
is thermally unstable, as will be shown below. In this
regard, other approaches have been suggested to increase
the thermal stability of GIC based on graphite nitrate .
One of them is the additional modiﬁ cation of graphite
nitrate immediately after the synthesis in order to sub-
stitute a part of HNO
molecules for molecules of other
substances, modiﬁ ers. This substitution may increase the
solvation of the NO
anion, which signiﬁ cantly affects
GIC stability . Previously, a wide variety of the modi-
ﬁ ers (carboxylic acids, nitriles, ethers and esters) has been
found, which increase stability of GIC based on graphite
nitrate . For industrial application, the most attractive
modiﬁ er is acetic acid, because of its unique stabilizing
properties and accessibility.
In the study, the thermally stable GICs with the largest
degree of the thermal expansion were synthesized in the