Russian Journal of Applied Chemistry, Vol. 78, No. 3, 2005, pp. 511 513. Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3,
005, pp. 517 519.
Original Russian Text Copyright
2
2005 by Yurchenko, Ivashchenko, Pilipenko, Pogrebova.
BRIEF
COMMUNICATIONS
Pyridinium Halides and Their Mixtures as Inhibitors of Steel
Corrosion in Sulfuric Acid Solutions
R. I. Yurchenko, S. V. Ivashchenko, T. N. Pilipenko, and I. S. Pogrebova
Kiev Polytechnic Institute, National Technical University of Ukraine, Kiev, Ukraine
Received October 15, 2004
Abstract Mixtures of 1-acylmethylpyridinium halides with equimolar amounts of pyridinium halides were
prepared by the Ortoleva King reaction. The inhibiting effect of various pyridinium halides and their mixtures
on corrosion of steel in sulfuric acid solutions was studied.
Previously we found [1, 2] that some of 1-phen-
acylmethylpyridinium bromides are relatively effec-
tive inhibitors of the acid corrosion of steel, especially
at elevated temperatures. These compounds were
prepared by alkylation of appropriate pyridine deriva-
tives with -bromoacetophenones.
strongly simplifies synthesis of 1-acylmethylpyridini-
um halides: it can be performed in one step without
using halomethyl ketones (lacrimators) and allows
preparation of pyridinium salts that cannot be ob-
tained by common methods. Moreover, this reaction
yields acylmethylpyridinium halides in mixtures with
pyridinium halides, which can enhance their corro-
sion-protective effect [4].
Corrosion inhibitors of this type can be prepared by
the Ortoleva King reaction [3], i.e., the reaction of
pyridine derivatives, iodine, and compounds contain-
ing labile hydrogen atoms. Since pyridine and its
derivatives act as both reagents and acceptors of the
forming hydrogen halide, this reaction gives, along
with the desired pyridinium salts, also the correspond-
ing pyridinium halides. For example, the reaction
of pyridine, acetophenone, and bromine yields an
equimolar mixture of 1-phenacylmethylpyridinium
bromide and pyridinium bromide:
EXPERIMENTAL
The synthesis was performed according to the
procedure described in [3]. The corrosion-protective
effect of the compounds prepared was evaluated using
the coefficients of corrosion deceleration and degree
of corrosion protection Z, calculated from the weight
loss of 08KP steel samples in 3 M sulfuric acid at 20
and 60 C and inhibitor concentration of 1 10 2
(see table).
M
Hal
2
+
H3C
R1
+
N
R
R
N
O
The coefficient of corrosion inhibition of 1-phen-
acylmethylpyridinium bromide (I-1) at 20 C is 11.3
Hal CH2
R1
O
[1]. This compound is formed by the Ortoleva King
+
.
+
N
reaction from pyridine, acetophenone, and bromine
in a mixture with pyridinium bromide and the coef-
ficient of corrosion inhibition of this mixture (in-
hibitor I-1a) is as high as 18.0. In the case of iodine,
the reaction yields 1-phenacylmethylpyridinium
iodide (I-2) and pyridinium iodide; the first com-
pound, when isolated pure, exhibits the coefficient of
inhibition of 17.7 at 20 C. The coefficient of corro-
sion inhibition of the resulting mixture (I-2a) is 24.3.
In the case of 1-phenacylmethyl-2-methylpyridinium
bromide (I-3), the coefficients of corrosion inhibition
are 15.5 and 209.1 [1], and for its mixture with
R
H
Hal
When the solubility of the resulting salts is strong-
ly different, they can be separated to prepare individ-
ual 1-acylmethylpyridinium halides. For example,
treatment with alcohol of the salt mixture formed in
the reaction of pyridine or 2-methylpyridine with
acetophenone in the presence of bromine or iodine
allows preparation of the corresponding 1-phenacyl-
methylpyridinium bromides and iodides with high
yields. In many cases, the Ortoleva King reaction
1
070-4272/05/7803-0511 2005 Pleiades Publishing, Inc.