ISSN 0965-5441, Petroleum Chemistry, 2006, Vol. 46, No. 6, pp. 428–433. © Pleiades Publishing, Inc., 2006.
Original Russian Text © A.G. Nazmutdinov, V.S. Sarkisova, N.N. Vodenkova, I.A. Nesterov, T.N. Nesterova, 2006, published in Neftekhimiya, 2006, Vol. 46, No. 6, pp. 458–463.
Study of the Liquid–Vapor Critical Temperatures
for Methyladamantanes and Their Mixtures with Cyclohexane
A. G. Nazmutdinov, V. S. Sarkisova, N. N. Vodenkova, I. A. Nesterov, and T. N. Nesterova
Samara State Technical University, Samara, Russia
e-mail: kinterm@samgtu.ru
Received April 30, 2006
Abstract—The liquid–vapor critical temperatures of individual 1,3-dimethyl- and 1,3,5-trimethyladamantanes
and their binary mixtures with cyclohexane were determined over the entire range of composition by means of
the ampule method. It was found that an excess of the critical temperatures over calculated values reached 20 K
for both mixtures studied. The predictive capabilities of several calculation methods are discussed.
DOI: 10.1134/S0965544106060089
Development of optimal technologies for separation sponding manner. This refinement is impossible unless
of complex hydrocarbon mixtures of different classes reliable experimental data are available.
suggests detailed testing of models and combination
rules used for the prediction of basic properties of indi-
vidual components and their solutions. The effective-
ness of a selected model is determined to a considerable
extent by the correctness of the prediction of one of the
critical properties, namely, the critical temperature
(íÒ), which forms the basis for the calculation of a large
number of parameters in terms of the law of corre-
sponding states [1, 2]
In this work, we determined the critical (liquid–vapor)
temperatures for 1,3-dimethyladamantane (1,3-DMA),
1,3,5-trimethyladamantane (1,3,5-TMA), cyclohexane
(CH), and CH–1,3-DMA and CH–1,3,5-TMA mixtures.
EXPERIMENTAL
Commercial cyclohexane (reagent grade for chro-
matography, 99.96%(GLC)) and the in-house synthe-
sized chemicals 1,3-dimethyladamantane and 1,3,5-tri-
methyladamantane were used.
1,3-DMA (or 1,3,5-TMA) was synthesized in two
successive steps, the exhaustive hydrogenation of
acenaphthene (or fluorene) to afford a mixture of per-
hydroacenaphthene (or perhydrofluorene) stereoiso-
mers and the liquid-phase isomerization of the stereoi-
somers on aluminum chloride [8, 11, 12].
To obtain the mixture of isomeric perhydroacenaph-
thenes (perhydrofluorenes), commercial acenaphthene
(fluorene) with a content of the title compound of at
least 98% was used. Before hydrogenation, acenaph-
thene (or fluorene) (100 g) was dissolved in hexane
(500 ml), the solution was placed in an autoclave, and
Raney nickel (10 g) prepared as described in [13] was
added. The autoclave was sealed and purged three
times with hydrogen. The hydrogenation was carried
out at a temperature of 423 K and a hydrogen pressure
of 1.5 MPa with stirring for 6 (or 10 h). The conversion
of acenaphthene or fluorene exceeded 99.5 (or 99%)
according to GLC data. After completion of hydroge-
nation, the catalyst was filtered off, cyclohexane was
removed by distillation, and a mixture of perhy-
droacenaphthene (or perhydrofluorene) stereoisomers
was obtained with a practically quantitative yield.
An analysis of experimental data on íÒ for individ-
ual cycloalkanes and their mixtures [1–7] showed that
the array of experimental data has to be substantially
complemented by information about entities of funda-
mental importance from practical and theoretical stand-
points. Of these entities, cage compounds occupy a spe-
cial place. The specifics of their molecular structure are
obvious and have been well documented in the litera-
ture [8–10]. The question is what is the significance of
such specifics in the formation of properties of materi-
als with the cage structure of their molecules.
In this work, we consider methyladamantanes (MA)
with bridgehead substituents, which have become rela-
tively available to date. These compounds are used as
intermediates for the synthesis of a variety of medicines
and other industrially important chemicals with unique
properties, as well as in the search for new biologically
active substances [8].
The theoretical interest stirred by these compounds
is due to the fact that the substituent-bearing bridge-
head carbon atom in adamantane is unique and seems
to match neither a quaternary carbon atom in substi-
tuted cyclohexane nor a quaternary carbon atom of ali-
phatic compounds. If this is indeed the case, the exist-
ing methods for the prediction of the critical properties
The mixture of perhydroacenaphthene (or perhy-
of organic compounds should be corrected in a corre- drofluorene) stereoisomers was isomerized at 343 K in
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