Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 7, pp. 1292−1296.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © L.V. Smirnova, I.I. Khamitov, E.N. Kropacheva, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 7, pp. 1221−1225.
Polymerization of 1,3-Butadiene under the Action
of Cobalt Catalyst in an Aliphatic Solvent
with Formation of Polymers Suitable
for Commercial Use
L. V. Smirnova, I. I. Khamitov, and E. N. Kropacheva
Sintel Public Joint-Stock Company, St. Petersburg, Russia
Received November 11, 2010
Abstract—Polymerization of 1,3-butadiene in an n-hexane solution in the presence of the catalyltic complex
cobalt 2-ethylhexanoate–diisobutylaluminum chloride–water–isoprene was studied. The conditions were found for
preparing cis-polybutadiene with the molecular-weight distributions ensuring the physicomechanical parameters
required for commercial applications.
Today cis-polybutadiene (PB) is produced in the world
using cobalt and neodymium complexes [1, 2]. In Russia,
cobalt catalytic systems have not been introduced into in-
dustrial production. These systems have been extensively
studied as applied to the polymerization of 1,3-butadiene,
especially in aromatic solvents [3–10]. The possibility of
using aliphatic and alicyclic solvents in these processes
was also demonstrated.
The goal of this study was to perform an active
process of 1,3-butadiene polymerization in an aliphatic
solvent under the action of a Ziegler-type cobalt system
to obtain cis-polybutadiene having the required molecular
weight and high level of physicomechanical and elastic
Synthesis of the catalytic complex cobalt 2-ethyl-
hexanoate–diisobutylaluminum chloride (DIBAC)–
О–isoprene and polymerization of 1,3-butadiene were
performed in an inert gas atmosphere under the conditions
commonly used in organometallic syntheses. Toluene
containing 0.030–0.035 wt % water and a 10% solution
of isoprene in dry toluene were mixed at a temperature
from –10 to –20°C. The resulting mixture was kept at
this temperature for 1 h. After that, toluene solutions of
cobalt 2-ethylhexanoate and DIBAC were added in suc-
cession. The resulting solution of the catalytic complex
was warmed to 20–25°С and kept at this temperature for
1 h. The catalytic complex thus prepared can be stored at
temperatures lower than –20°С for several days without
changes in the activity.
For the 1,3-butadiene polymerization, an ampule (or
a batch apparatus) was charged with dry n-hexane, dry
monomer, and “wet” toluene. The mixture was thermo-
stated at –10 to –20°С, after which the calculated amount
of the catalytic complex was added. The concentration of
the cobalt salt in the mixture being polymerized was с ≥
3 × 10
M. The total amount of toluene in the mixture was
10–15 vol % relative to n-hexane. It should be noted that,
without toluene, the catalytic system was heterogeneous.
Then the mixture was warmed to 20°С for the polymer-
ization. Owing to the use of the catalytic complex, the
initiation step in polymerization of 1,3-butadiene was
absent. The PB was isolated, washed, stabilized, and dried
by standard procedures.
The average molecular weights М
, and М