Russian Journal of Applied Chemistry, 2012, Vol. 85, No. 6, pp. 945−948.
Pleiades Publishing, Ltd., 2012.
Original Russian Text © V.P. Zakharov, V.Z. Mingaleev, Yu.V. Morozov, I.Sh. Nasyrov, E.M. Zakharova, 2012, published in Zhurnal Prikladnoi Khimii, 2012,
Vol. 85, No. 6, pp. 965−968.
AND POLYMERIC MATERIALS
Enhancement of the Activity of a Neodymium Catalyst
for the Synthesis of Stereoregular Polyisoprene
V. P. Zakharov
, V. Z. Mingaleev
, Yu. V. Morozov
I. Sh. Nasyrov
, and E. M. Zakharova
Bashkir State University, Federal State Budget Educational Institution of Higher Professional Education,
Ufa, Bashkortostan, Russia;
Institute of Organic Chemistry, Ufa Scientiﬁ c Center, Russian Academy of Sciences, Ufa, Bashkortostan, Russia
Sintez-Kauchuk Public Joint-Stock Company, Sterlitamak, Bashkortostan, Russia
Received February 20, 2012
Abstract—A new ligand based on two pyrazole cycles linked with each other was synthesized. Its interaction with
Cu(II), Ni(II), Co(II), Mn(II), Cr(III), Zn(II), and Cd(II) cations in ethanol was studied by the spectrophotometric
Intensiﬁ cation of the complexation of neodymium
chloride with isopropyl alcohol by preliminary mixing of
the reaction mixture in a tubular turbulent diffuser–con-
fuser apparatus was studied. The procedure ensures ac-
celeration of the process, incorporation of a larger amount
of isopropyl alcohol in the complex, and high activity of
the neodymium catalyst in the polyisoprene synthesis.
Catalytic systems based on lanthanide compounds are
effective catalysts of polymerization of dienes (mainly
of isoprene and butadiene). A distinctive feature of these
systems is high cis stereospeciﬁ city. In particular, the
synthesized polybutadiene and polyisoprene contain ap-
proximately 98% 1,4-cis units .
Catalytic systems formed by the reaction of lanthanide
chloride (catalyst) with an organoaluminum compound
(cocatalyst) exhibit low activity in diene polymerization
[1, 2]. The catalyst activity is considerably enhanced on
introducing electron-donor compounds . An electron-
donor ligand increases the extent of the covalence of the
lanthanide–halogen bond and thus favors alkylation with
an organoaluminum compound with the formation of
lanthanide–carbon bonds active in polymerization [1, 2].
Thus, lanthanide catalytic systems highly active in diene
polymerization are formed in the reaction of an organoalu-
minum compound with neodymium chloride in the form
of a complex compound with an electron-donor ligand.
As shown in , the complex of neodymium chlo-
ride with tributyl phosphate (TBP) is formed slowly.
The process is accompanied by essential changes in the
structure of the crystal lattice of both the initial NdCl
and the complex NdCl
·nTBP. The complexation with the
organic ligand results in loosening of the crystal structure
of neodymium chloride and in formation of an amorphous
precipitate of NdCl
Today isoprene rubber is commercially produced in
Russia using alcohol complexes of neodymium chloride
. In this connection, we examined in this study the pos-
sibility of intensifying the complexation of neodymium
chloride with isopropyl alcohol by preliminarily mixing
the initial reaction mixture in a turbulent diffuser–con-
fuser apparatus to obtain a highly active catalyst of
stereospeciﬁ c polymerization of isoprene. The results
obtained are prerequisites for improvement of the process
for preparing gel-free neodymium isoprene rubber.
The neodymium component of the catalytic complex
was prepared from the hydrate NdCl
) with isopropyl alcohol (IPA) in liquid paraf-
ﬁ n at 25°С. The reactant molar ratio was NdCl
: IPA =