1070-4272/05/7811-1880+2005 Pleiades Publishing, Inc.
Russian Journal of Applied Chemistry, Vol. 78, No. 11, 2005, pp. 1880!1883. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 11,
2005, pp. 1912!1916.
Original Russian Text Copyright + 2005 by Belaya, Ovcharova, Filippenko, Nikolaevskii, Palagushkina.
AND INDUSTRIAL ORGANIC CHEMISTRY
Aminophenols as Inhibitors of Oxidation of Nujol
N. I. Belaya, O. Yu. Ovcharova, T. A. Filippenko,
A. N. Nikolaevskii, and L. A. Palagushkina
Donetsk National University, Donetsk, Ukraine
Received May 4, 2005
Abstract-Antioxidant properties of aminophenols in initiated oxidation of Nujol were studied by
a chemiluminescence procedure.
Polyfunctional antioxidants (AO) with several reac-
tive groups can be used to stabilize fats and oils.
Among these compounds are aminophenols (APs).
To assess practical applicability of APs for inhibition
of radical chain oxidation of organic compounds, their
antioxidant power (AOP) with respect to model sys-
tems should be determined and features of the
behavior of APs in complex substrates (liquid fuels,
mineral oils, etc.) should be taken into account.
In this study we examined the antioxidant power of
aminophenol with respect to Nujol by chemilumines-
cence (CL) observed during the oxidation.
We used Nujol (Merck) as received. Azobisisobu-
tyronitrile (AIBN) (pure grade) double-recrystallized
from absolute ethanol was used as the free radical
source . CL activator, 9,10-dibromoanthracene
(DBA), was prepared and purified by the procedure
described in . Aminophenols were prepared by the
procedures described in [4, 5]. These compounds were
identified and characterized by thin-layer chroma-
tography, IR spectroscopy, and elemental analysis.
The CL kinetics in the course of initiated oxidation
of Nujol in the presence and in the absence of AO was
monitored with a chemiliminesecnce unit described
The reactivity of aminophenols (InH) in reaction
with peroxy radicals of Nujol (ROO) (2) was charac-
terized by the ratio k
and stoichiometric coef-
ficient of inhibition (f).
76 Products, (1)
+ PhOH 76 ROOH + PhO
Since the composition of the substrate being oxi-
dized is complex and variable, the rate constant (k
of recombination of peroxy radicals (1) is unknown
and hence the quantity k
Oxidation of Nujol initiated by AIBN was per-
formed at 333 K in chlorobenzene at a volume ratio of
1 : 1. The initiation rate (v) of Nujol oxidation was
calculated from Eq. (3). For this purpose, the induc-
tion period of Nujol oxidation in the presence of a
reference inhibitor (Ionol) was determined. The inhibi-
tion coefficient (f) of Ionol is 2 .
= f [InH]
is the initial Ionol concentration, M.
To determine this parameter, the chemilumines-
cence kinetic curves were linearized in the coordinates
of Eq. (4):
and I are the chemiluminescence intensities
in the absence and in the presence of AO, respec-
The apparent rate constant k
was calculated from
the slope of the linearized kinetic curves of CL (j)
(Fig. 1b) by the equation
The number of radicals decaying on a single AO
molecule was calculated from the experimental induc-
tion period of oil oxidation (t) in the presence of AP
by Eq. (3).
After addition of the examined AOs into the sys-
tem, the CL intensity (I) decreases as compared to that