Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 4, pp. 685−687.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
I.B. Sladkov, E.I. Arishina, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 4, pp. 688−690.
Critical Parameters of Chlorinated Tetramethyl-
I. B. Sladkov and E. I. Arishina
St. Petersburg State Polytechnical University, St. Petersburg, Russia
Received February 25, 2009
Abstract—The critical parameters of chlorinated tetramethyl- and tetraethylgermane were determined by
calculational methods. The reliability of calculated data was confirmed by several independent methods.
Organoelemental compounds find ever widening
application, in particular, in such important chemical
technologies as organic synthesis and preparation of metal
coatings, plastics, semiconductor materials, etc. [1, 2].
The critical parameters of chlorinated tetraethylsilane 
and tetraethyl tin  were determined earlier.
Here, we determined the critical parameters of
chlorinated tetramethyl- and tetraethylgermane.
The critical parameters were calculated by equations
whose reliability was conﬁ rmed [3, 4] for similar organo-
metallic compounds of Group IV elements. The critical
, K, and critical volume V
were calculated by the formulas
= 80Π −
where θ is the reduced temperature at the boiling point
), which was calculated as
θ = 0.092 ln Π + 0.515,
where Π is the parachor, J
, whose values
were taken from [5, 6].
The critical pressure P
, MPa, was calculated by the
where b is the Van der Waals constant, cm
was calculated using the molar volume of a liquid at the
boiling point by the equation 
b = 1.27V
Table 1 lists the initial data (boiling point parameters)
[7–10] and the calculated critical parameters of chlorinated
tetramethyl- and tetraethylgermane.
The reliability of the calculated data was assessed by
the following methods. At the present time, the properties
of molecular liquids (density, saturated vapor pressure)
can be predicted with a high reliability by thermodynamic
similarity theory methods  utilizing critical parameters
of a substance as the initial data. Chlorinated tetramethyl-
and tetraethylgermane belong to little studied compounds,
but some of them were characterized by experimental
density in the liquid state and saturated vapor pressure
Here, we calculated these characteristics by the
thermodynamic similarity theory equations with the
use of the T
, and V
values obtained. By comparing
the calculated values of these characteristics with the
corresponding experimental data it is possible to assess
the reliability of the critical parameters determined.
To this end, we calculated the density of the liquid ρ,
, by the Mathias equation 
ρ = (M/V
)[2(2 − T/T