298 CHEMISTRY AND TECHNOLOGY OF EXPLOSIVESBelayev and Yuzefovich [65] found the boiling point of TNT at 2 mm Hg pressure
to be 190°C and at 50 mm Hg 245-250°C; these values are consistent with those
quoted above.
The authors have determined the boiling point of trinitrotoluene at normal
pressure by extrapolation and found it to be 300±10°C. The direct determination
of the boiling point, is of course impossible, since it is near to the initiation tem-
perature of the substance.
A. J. B. Robertson [66] reported 345°C as the condensation temperature of
trinitrotoluene vapours at 760 mm Hg, and 232°C at 30 mm Hg. Considering that
the experimental conditions were difficult, it should be accepted that the results
of all three workers are consistent. The value of 530°C, earlier determined by
Menzies [67] by extrapolation of the results of vapour pressures measurements and
heats of evaporation, is less probable.
Vapour pressures of trinitrotoluene have been determined by several authors.
The first measurements were carried out by Verola [68] between 1911 and 1912.
He found a value of 25 mm Hg at 183°C and soon after attaining this temperature
decomposition began. The evolution of gases causes the pressure to rise rapidly.
The rate was as high as 20 mm Hg/min.
Menzies [67], A. J. B. Robertson [66] and G. Edwards [69] have also carried
out investigations on the vapour pressures of α− trinitrotoluene.
Edwards reported the following vapour pressures:Temperature, °C Pressure, cm Hg
60.1 5.43 x 10-5
78.5 6.44 x 10-4
80.2 7.16 x 10-4
82.4 7.96 x 10-4
99.5 4.07 x 10-3
110.6 8.26 x 10-3
131.1 3.48 x 10-2
141.4 6.21 x 10-2Absorptivity. α− Trinitrotoluene is relatively strongly adsorbed on chromato-
graphic columns and can be separated in this way from nitro derivatives of toluene
with a lower number of nitro groups. Various columns have been suggested filled
with basic adsorbents, but these were liable to produce a deep change in the trinitro
compounds (Halfter [70], Ovenston [71]). A considerable improvement was reported
by Kemula and his co-workers [72], using his chromate-polarographic method.
Here the chromatographic column was filled with pulverized rubber swollen with
n-heptane (immobile phase), the mobile phase being 0.2 M KI in a 50/50 methanol-
water solution of the nitro compounds.
When the column was fed with a mixture of mono-, di- and tri-nitrotoluenes,
p- nitrotoluene was eluted first, dinltrotoluene followed, and the last substance
eluted was α− trinitrotoluene.
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