Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 7, pp. 1178−1187.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
B.M. Ginzburga, Sh. Tuichiev, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 7, pp. 1082−1091.
OF SYSTEMS AND PROCESSES
Inﬂ uence of the Molecular Structure on the Phase Transition
Temperatures of Mononuclear Aromatic Compounds
B. M. Ginzburg
and Sh. Tuichiev
Institute of Mechanical Engineering Problems, Russian Academy of Sciences, St. Petersburg, Russia
Tadjik State National University, Dushanbe, Tadjikistan
Received February 24, 2009
Abstract—Boiling and melting points in relation to the molecular structure were examined for 60 mononuclear
aromatic compounds. Phase transition temperatures were analyzed as inﬂ uenced by the structural isomerism and
symmetry of the molecules.
Aromatic compounds (benzene, toluene, xylenes)
play an important role in science and technology. They
ﬁ nd extensive and diverse application as solvents, in
particular, in preparation of medicines, explosives (e.g.,
trotyl), plastics, photodevelopers, dyes, and many other
compounds [1, 2]. Of much signiﬁ cance in choosing
solvents for speciﬁ c applications are their phase transition
temperatures, boiling and melting points.
and melting T
points in relation to the
molecular structure were analyzed for the ﬁ rst time for
fairly simple compounds, hydrides of various elements,
by Pauling in the 1940s and discussed in a number of
monographs [3, 4]. Kitaigorodskii [5, 6], Bokii , and
Kotel’nikova and Filatov  carried out crystal-chemical
analysis of the structure and properties of various
This research line underwent vigorous development in
the years that followed, as suggested by tens of relevant
theoretical, semiempirical, calculational, and experimental
studies, which can be conditionally subdivided into two
The first group integrates studies that attempted
establishing relationships for a set of molecular
characteristics of a substance (“descriptors”) and
predicting their boiling (or melting) point in the most
general form. Examples can be found in studies by
Meissner , Todos et al. [10–12], Lydersen ,
Joback et al. , Somayajuluу , and other. Of much
signiﬁ cance for those studies was the so-called “group
contributions” method [16, 17].
Virtually all the generalizing studies employed the
parachor concept . For example, Meissner established
a semiempirical relationship 
= (637 R
+ B)/P, (1a)
is the molecular refraction for the D line of Na;
B, constant for a speciﬁ c class of compounds; and Р =
). In the latter expression, P is parachor; M,
molecular weight of the substance; σ, surface tension,
; and ρ
, densities of the liquid and
vapor, respectively, g cm
, at temperatures distant from
the critical point. In this case ρ
P ≈ V
is the molar volume of the liquid.
Parachor is temperature-independent and exhibits
the additivity property: The molar parachor (parachor
per mole of substance) is the sum of the parachors of the
atoms or molecular groups constituting the molecule.
Using relationship (1b), Steraski and Machwart
 plotted a nomogram for determining Т