ISSN 1070-4272, Russian Journal of Applied Chemistry, 2014, Vol. 87, No. 10, pp. 1529−1535. © Pleiades Publishing, Ltd., 2014.
Original Russian Text © A.V. Lebedev, V.D. Sheludyakov, P.A. Storozhenko, V.S. Gurskii, Yu.V. Tsapko, I.M. Yasnev, A.G. Egorov, L.V. Osetrova, 2014, published
in Zhurnal Prikladnoi Khimii, 2014, Vol. 87, No. 10, pp. 1480−1486.
Possibilities of Using Trimethylpentaphenyltrisiloxane
as Coolant for Removing Low-Potential Heat
A. V. Lebedev
, V. D. Sheludyakov
, P. A. Storozhenko
, V. S. Gurskii
, Yu. V. Tsapko
I. M. Yasnev
, A. G. Egorov
, and L. V. Osetrova
State Research Institute of Chemistry and Technology of Organoelement Compounds,
sh. Entuziastov 38, 105118 Moscow, Russia
Aleksandrov Research Institute of Technology, a/ya 22, Sosnovyi Bor, Leningrad oblast, 188540 Russia
Lebedev Research Institute of Synthetic Rubber, ul. Gapsalskaya 1, St. Petersburg, 198035 Russia
e-mail: email@example.com, firstname.lastname@example.org
Received September 29, 2014
Abstract—The resistance of commercial trimethylpentaphenyltrisiloxane to heat and to thermal oxidation was
studied. The limits of its use as coolant in systems for removing low-potential heat were determined. Instrumen-
tal methods were developed and tested for monitoring the condition of siloxane in the course of its prolonged
operation as coolant.
In 1962, Crawley et al.  reported the development
of an ultra-high-vacuum working liquid for oil diffusion
pumps under DC-705 trade name. It was produced by
Dow Corning (the United States) and ensured the limiting
vacuum of up to 10
mmHg or even better when using
water-cooling traps. The base component of the product
was symmetrical trimethylpentaphenyltrisiloxane
(I). Later this product
found very wide use in vacuum engineering owing to the
most favorable set of its characteristics. In particular, it
ensured extremely low residual pressure in the evacuated
system and exhibited high heat and radiation resistance.
In the former Soviet Union and then in the Russian
Federation, analogous substance is produced under
FM-1 liquid trade name. Recently China also started to
produce this substance under oil 275 trade name. High
heat and radiation resistance are priority characteristics
that should be exhibited by working liquids of modern
systems for removing low-potential heat in compact high-
power nuclear energy installation, which are now under
development, including working bodies of open space
cooling systems based on principles of carcass-free liquid
droplet radiators .
Therefore, it seemed topical to study the stability of
commercial compound I under critical conditions of its use
and to evaluate the efﬁ ciency of methods for monitoring
its stability. As critical conditions we chose temperatures
higher than 300°С and the presence of real industrial and
operation impurities in the suggested coolant.
Si NMR spectroscopy and chromatography were
chosen as basic monitoring methods.
The chloride ions, which are capable to react at high
temperatures both with molecules of the tested siloxane
and with structural materials of the cooling system, were
detected in samples of FM-1 liquid by ion chromatography
on the level of 10–15 mg L
. Such content may be due
to the use of water with impurities of chlorides and
hydrochloric acid proper in industrial synthesis of I.
We have found that chloride ions, which exert negative
corrosive effect, can be completely removed by twofold
extraction of a toluene solution of commercial siloxane I
with double-distilled water, followed by solvent removal
in a vacuum. Direct extraction is unfeasible because of
close densities of water and siloxane.
The content of dissolved gases in commercial
compound I was determined by gas chromatography. The