Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 5, pp. 875−879.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
D.P. Shalyminova, E.N. Cherezova, A.G. Liakumovich, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 5, pp. 821−825.
ORGANIC SYNTHESIS AND INDUSTRIAL
Styrylation of Phenol in the Presence of Cation-Exchange
Resins. Inﬂ uence of the Product Composition
on Its Stabilizing Performance in Rubber
D. P. Shalyminova, E. N. Cherezova, and A. G. Liakumovich
Kazan State University of Technology, Kazan, Tatarstan, Russia
Received June 30, 2008
Abstract—Methylbenzylated phenols were prepared by catalytic reaction of phenol with styrenes. The effect of
a series of cation-exchange resins on the product composition was examined, and the stabilizing performance of
the products in rubber was evaluated.
Alkyl(aryl)phenols, including methylbenzylated
phenols (MBPs), are widely used in polymer chemistry
as antioxidant additives. The commercial procedure for
preparing these compounds is the reaction of phenol
with styrene or α-methylstyrene, catalyzed by mineral
or organic acids under homogeneous conditions .
The reaction product is a mixture of mono-, di-, and
trisubstituted MBPs of various structures .
However, performing the reaction in the presence
of a homogeneous catalyst makes it necessary to wash
the product to remove the catalyst, which results in
formation of a large amount of wastewater. This fact
strongly impedes introduction of MBPs into the practice
of polymer stabilization .
Among recent studies on synthesis of arylaklyl-sub-
stituted phenols, we should particularly mention studies
performed with heterogeneous catalysts [4, 5]. In this
case, the catalyst can be readily separated from the
reaction mixture; furthermore, it can be reused.
In this study we examined the inﬂ uence of structural
characteristics of cation-exchange resins on the composi-
tion of the product formed in the reaction of phenol with
styrene. We also examined how the composition of the
resulting MBP correlates with its stabilizing performance.
The starting substances were phenol [GOST
(State Standard) 23519–93; mp 40.9, bp 182°C; d
1.0576 g cm
] and styrene (GOST 1003–93; bp 145.2°C,
0.9060 g cm
). The thermal polymerization inhibitor
was 2,6-di-tert-butyl-4-methylphenol (GOST 28584–90,
mp 70°C). The catalysts were KU-23 (GOST 20298–74),
Lewatit K-2629 and K-2431 (Bayer), and Purolite CT-
151 (Purolite). The stabilizing effect was examined with
SKI-3 isoprene rubber (GOST 14925–79).
The progress of the reaction of phenol with styrene
was monitored by gas–liquid chromatography (GLC)
with a Waters 440 device equipped with a μBondapak
column 4 mm i.d. The eluent was acetonitrile, ﬂ ow
rate 1 ml min
. Methylbenzylated phenols were detected
by UV absorption at 265 nm, sensitivity 1.28 absorption
units for the whole scale.
The induction period of rubber oxidation was
determined by the standard procedure .
The kinetics of accumulation of carbonyl groups in
the course of thermal oxidation of SKI-3 rubber was
studied by IR spectroscopy with a UR-75 device. As
analytical band we used the absorption band at
corresponding to stretching vibrations of the
Variation of the molecular weight of the polymer
in the course of thermal oxidation was monitored by
viscometry . To characterize the rubber stability in
the course of thermal oxidation, we used the degradation
coefﬁ cient K