1-Phenacylmethyl-2-(acylaminothiocarbonylamino)pyridinium bromides as protectors of steel acid corrosion

Article abstract of DOI:10.1134/S1070427207040325

Inhibiting effect of 1-phenacylmethylpyridinium bromides containing acylthiourea substituents in the pyridine ring on corrosion of mild steel in sulfuric acid (3 M) was studied.

Full text of DOI:10.1134/S1070427207040325

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 4, pp. 675 677.
Pleiades Publishing, Ltd., 2007.
Original Russian Text
pp. 691 692.
R.I. Yurchenko, I.S. Pogrebova, T.N. Pilipenko, 2007, published in Zhurnal Prikladnoi Khimii, 2007, Vol. 80, No. 4,
BRIEF
COMMUNICATIONS
1-Phenacylmethyl-2-(acylaminothiocarbonylamino)pyridinium
Bromides as Protectors of Steel Acid Corrosion
R. I. Yurchenko, I. S. Pogrebova, and T. N. Pilipenko
Kiev Polytechnic Institute, National Technical University of Ukraine, Kiev, Ukraine
Received May 11, 2006; in final form, August 2006
Abstract Inhibiting effect of 1-phenacylmethylpyridinium bromides containing acylthiourea substituents
in the pyridine ring on corrosion of mild steel in sulfuric acid (3 M) was studied.
DOI: 10.1134/S1070427207040325
The inhibiting properties of 1-phenacylmethylpyr-
S
idinium bromides containing, in the 2-position of
1. NH4NCS
RC(O)Cl
RC(O)N
H
N
N
H
the pyridine ring, the NH2 [1], NH(C)OR [2],
NHC(O)NHR, and NHC(S)NHR [3] groups have
been studied previously. The thiourea derivatives were
found to be the most active. In this study, we ex-
amined ureides I VIII as a logical continuation of
the above studies: 1-(2-oxo-2-phenylethyl)-2-(3-phen-
ylureido)pyridinium bromide I, 1-(2-oxo-2-phenyleth-
yl)-2-[3-(4-methylphenyl)ureido]pyridinium bromide
II, 1-(2-oxo-2-phenylethyl)-2-[3-(4-methoxyphenyl)-
ureido]pyridinium bromide III, 1-(2-oxo-2-phenyl-
ethyl)-2-[3-(4-bromomethylphenyl)ureido]pyridinium
bromide IV, 1-(2-oxo-2-phenylethyl)-2-[3-(4-chloro-
methylphenyl)ureido]pyridinium bromide V, 1-(2-oxo-
2-phenylethyl)-2-[3-(2-furyl)ureido]pyridinium bro-
mide VI, 1-(2-oxo-2-phenylethyl)-2-[3-(adamant-1-
yl)ureido]pyridinium bromide VII, and 1-(2-oxo-2-
phenylethyl)-2-[3-(undec-1-yl)ureido]pyridinium bro-
mide VIII.
2.
H2N
N
S
BrCH2COPh
+
RC(O)N
N
N
H
H
Br
O
where R is Ph (I), 4-CH3C6H4 (II), 4-CH3OC6H4
(III), 4-BrC6H4 (IV), 4-ClC6H4 (V), 2-furyl (VI),
1-adamantyl (VII), and 1-undecyl (VIII).
The composition of the compounds obtained was
1
confirmed by IR and H NMR spectra.
EXPERIMENTAL
These compounds are acyl derivatives of thiourea
and contain RC(O)NHC(S)NH groups in the 2-posi-
tion of the pyridine ring. It is known that -dicar-
bonyl compounds are often used in organic chem-
istry as complexing agents. Therefore, we can expect
that the structure of substituents taken will be favor-
able for the protective properties of the compounds
studied.
A mixture of an appropriate acid chloride prepared
by reaction of the acid with thionyl chloride (2
2
2
10 mol), ammonium thiocyanate (2.5 10 mol),
and anhydrous acetone (15 ml) was stirred for 30 min,
2
after which 2-aminopyridine (2 10 mol) was ad-
ded, and stirring was continued for an additional 1 h.
The reaction mixture was treated with a small portion
of water, and, the next day, the precipitate was
3
Compounds I VIII were synthesized by the reac-
tion of acyl chlorides, ammonium thiocyanate, and
2-aminopyridine, followed by treatment of the com-
pounds obtained with -bromoacetophenone:
separated. Equimolar amounts (1.5 10 mol) of
the compound prepared and -bromoacetophenone
were refluxed in 15 ml of ethyl acetate for 3 h, and
the precipitate was separated. The yields (%) and
675

676
YURCHENKO et al.
Corrosion inhibition coefficient and degree of protection, Z, for 08KP steel in 3 M H2SO4 in the presence of 1-phen-
acylmethylpyridinium bromides I VIII
40 C
60 C
80 C
Com-
pound
R
Z, %
Z, %
Z, %
I
II
III
IV
V
VI
VII
VIII
C6H5
23.90
29.87
36.70
22.76
22.76
41.56
39.80
38.24
95.82
96.66
97.27
95.60
95.60
97.59
97.48
97.38
129.40
373.10
396.42
103.40
121.20
218.70
380.56
328.10
99.22
99.73
99.75
99.03
99.17
99.54
99.73
99.69
41.70
190.10
125.10
56.55
103.60
119.00
192.75
102.90
97.60
99.47
99.22
98.23
99.03
99.16
99.48
99.02
4-CH3C6H4
4-CH3OC6H4
4-BrC6H4
4-ClC6H4
2-Furyl
1-Adamantyl
1-Undecyl
melting points ( C) of I VIII are as follows: I, 40,
229 232; II, 50, 198 200; III, 75, 195 205; IV, 70,
210 212; V, 71, 196 203; VI, 69, 218 220; VII, 35,
227 229; and VIII, 70, 212 215.
concentration as for the previously studied 1-phen-
acylmethylpyridinium bromides.
Nevertheless, the tests performed showed that com-
pounds I VIII are fairly efficient inhibitors of steel
acid corrosion (see table). The corrosion inhibition
coefficients found for saturated solutions in 3 M
H2SO4 vary within the ranges 15.79 26.47 at 20 C,
22.76 41.56 at 40 C, 103.40 396.42 at 60 C,
and 41.70 192.80 at 80 C. Voltammetric measure-
ments on steel with VI and VII at 20 C showed that
these compounds behave as mixed-type inhibitors af-
fecting the rate of both anodic and cathodic processes
(see figure). Calculations based on the formal theory
of inhibition [4] indicate that corrosion is inhibited
by these compounds at 40 C by the energy-blocking
mechanism.
The corrosion-protective properties I VIII were
evaluated gravimetrically at 20, 40, 60, and 80 C by
the inhibition coefficient and degree of protection,
Z, of a 08KP steel in 3 M sulfuric acid [1]. Unfor-
tunately, the poor solubility of the compounds ob-
tained in 3 M H2SO4 prevented attaining the same
Introduction of MeO group into the p-position of
the benzene ring in I or replacement of the phenyl
substituent with a furyl group enhances the protective
properties, which is in accordance with the chemical
nature of the substituents introduced, but the extent
of enhancement is substantially lower than that in
the series of the previously studied compounds [2, 3].
At 60 C, the corrosion inhibition coefficient for ureide
III is only three times higher, and for VI, two times
higher than that for I.
CONCLUSIONS
(1) It was found that the steel corrosion inhibition
coefficients for saturated solutions of 1-phenacylmeth-
yl-2-(acylaminothiocarbonlylamino)pyridinium bro-
mides in 3 M sulfuric acid vary within the ranges
15.79 26.47 at 20 C, 22.76 41.56 at 40 C, 103.40
(1 3) Cathodic and (1 3 ) anodic polarization curves re-
corded at 20 C on 08 KP steel in 3 M H SO and in so-
2
4
lutions saturated with VI and VII. (i) Current density
and (E) potential. Solution: (1, 1 ) supporting electrolyte,
(2, 2 ) with VI, and (3, 3 ) with VII.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 4 2007

1-PHENACYLMETHYL-2-(ACYLAMINOTHIOCARBONYLAMINO)PYRIDINIUM BROMIDES
677
396.42 at 60 C, and 41.70 192.80 at 80 C; the degree
of metal surface protection is 95.6 99.7%.
Kras’ko, E.M., Zh. Prikl. Khim., 2003, vol. 76, no. 11,
pp. 1814 1818.
2. Yurchenko, R.I., Pogrebova, I.S., Pilipenko, T.N., and
Shubina, T.E., Zh. Prikl. Khim., 2004, vol. 77, no. 7,
pp. 1132 1135.
(2) Voltammetric measurements showed that
the compounds studied behave as mixed-type inhib-
itors affecting the rates of both anodic and cathodic
processes. Corrosion is inhibited by these compounds
by the energy-blocking mechanism.
3. Yurchenko, R.I., Pogrebova, I.S., Pilipenko, T.N., and
Shubina, T.E., Zh. Prikl. Khim., 2006, vol. 79, no. 12,
pp. 1993 1997.
REFERENCES
4. Antropov, L.I., Zashch. Met., 1977, vol. 13, no. 4,
1. Yurchenko, R.I., Pogrebova, I.S., Pilipenko, T.N., and
pp. 387 399.
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 80 No. 4 2007