Fungicidal Activity of S-Esters of Thiocarboxylic Acids as Antimicrobial Additives to Petroleum Products

Article abstract of DOI:10.1134/S096554411901002X

Abstract: A variety of aliphatic and aromatic S-esters of thiocarboxylic acids have been tested for antimicrobial activity. The relationship between the chemical structure of the compounds R¹SC(O)R² and their toxicity for microorganisms has been revealed, and the effect of various functional groups on the antimicrobial properties has been shown. The cooling lubricant IKhP-45E with S-aryl thioacetate additives has been tested. It has been shown that the additives used (0.25–0.5 wt %) inhibit the growth of all the studied microorganisms; however, their activity with respect to fungi is higher. The introduction of S-aryl thioacetates provides the resistance of these oils to microbiological deterioration to retain the physicochemical properties for a long period of time.

Full text of DOI:10.1134/S096554411901002X

ISSN 0965-5441, Petroleum Chemistry, 2019, Vol. 59, No. 1, pp. 99–105. © Pleiades Publishing, Ltd., 2019.
Russian Text © I.A. Aliev, L.A. Belovezhets, L.A. Oparina, 2019, published in Neftekhimiya, 2019, Vol. 59, No. 1, pp. 91–97.
Fungicidal Activity of S-Esters of Thiocarboxylic Acids
as Antimicrobial Additives to Petroleum Products
I. A. Alieva, L. A. Belovezhetsb, *, and L. A. Oparinab
aBaku State University, Baku, AZ 1148 Republic of Azerbaijan
bFavorsky Institute of Chemistry, Irkutsk, Siberian Branch, Russian Academy of Sciences, Irkutsk, 664033 Russia
*e-mail: lyu-sya@yandex.ru
Received January 11, 2018; Revised March 15, 2018; Accepted July 26, 2018
Abstract—A variety of aliphatic and aromatic S-esters of thiocarboxylic acids have been tested for antimicro-
bial activity. The relationship between the chemical structure of the compounds R1SC(O)R2 and their toxic-
ity for microorganisms has been revealed, and the effect of various functional groups on the antimicrobial
properties has been shown. The cooling lubricant IKhP-45E with S-aryl thioacetate additives has been tested.
It has been shown that the additives used (0.25–0.5 wt %) inhibit the growth of all the studied microorgan-
isms; however, their activity with respect to fungi is higher. The introduction of S-aryl thioacetates provides
the resistance of these oils to microbiological deterioration to retain the physicochemical properties for a long
period of time.
Keywords: S-alkyl and S-aryl thiocarboxylates, petroleum products, biocide additives, antimicrobial activity
DOI: 10.1134/S096554411901002X
Like other types of petroleum-derived fuels, avia- would attract constant attention and would require
massive expenditures [6]. The main method of protec-
tion from the microbiological deterioration of petro-
leum products is the use of special antimicrobial addi-
tives, biocides. The search for organic compounds, the
introduction of which to petroleum products can pro-
tect them from the harmful effects of microorganisms,
as well as the studies on the investigation of the mech-
anism of action of antimicrobial substances are cur-
rently relevant.
tion fuel is readily deteriorated by microorganisms
during storage, transportation, and operation. As a
result of biodeterioration, its physicochemical and
operational properties substantially worsen, which can
be a reason for the faulty operation of aircraft equip-
ment [1]. The synthesis of aggressive metabolites, first
of all, organic acids, leads to the intensification of the
metal corrosion and depressurization of fuel tanks.
The accumulation of fungi biomass leads to the failure
of instruments and equipment because pipelines, noz-
zles, clack valves, pipe bends for fuel level sensing, as
well as fuel system filters of airplanes become clogged
in this case. In addition, all the microbiological pro-
cesses which occur with aviation fuel intensify multi-
fold in warm and humid climate (subtropical and trop-
ical zones) [2, 3]. In such cases, crash situations can
occur, which happened to TU-204 airplanes which
operated under tropical conditions [4]. The main
S-esters of thiocarboxylic acids R1SC(O)R2 play an
important role in bioorganic synthesis [7]. Thiocar-
boxylate groups are present in the structure of com-
pounds possessing a wide range of biological activity
[8, 9]. It is recognized that the bactericidal action of
garlic and ramson is due to the derivatives of structur-
ally similar allyl sulfides and sulfoxides [10]. However,
before the beginning of our works, there was no infor-
mation about the bactericidal and fungicidal activity of
microorganisms which cause the biodeterioration of the compounds of this class. In order to expand the
range of biocide additives and find the relationship
between their structure and antimicrobial properties,
the influence of S-esters of thiocarboxylic acids with
various structures on the sources of microbiological
deterioration of petroleum products was studied.
fuels are bacteria of Pseudomonas, Micrococcus, and
Mycobacterium genera as well as fungi C1adosporium,
Aspergillus, Рenicillium, A1ternaria, etc. Here, Pseudo-
monas aeruginosa bacteria and Cladosporium resinae
fungi (“kerosene fungus”) are detected in petroleum
products more often than other microorganisms [5].
Full extermination of microorganisms developing in
aviation fuels by any physical or physicochemical
methods is impossible, because of which the problem
of protecting aviation fuels from biodeterioration
EXPERIMENTAL
1H and 13C NMR spectra were obtained on a Jeol
FX-90Q spectrometer in a CDCl3 solution using
99

100
ALIEV et al.
Me4Si as the internal standard. IR spectra were
recorded on a JFS-25 spectrometer (thin film, KBr).
The S-esters of thiocarboxylic acids were synthesized
according to a known procedure [11, 12]. Phenylace-
tone, 4-fluorophenyl acetate, and 8-hydroxyquinoline
were commercial products.
S-(3-methylphenyl) thioacetate (6): yield 14.9 g
(90%), bp 96°C (3 mmHg), 20 1.5572, 20 1.0886. IR
nD
d4
spectrum (thin film, ν, cm–1): 1715 (C=O). 1H NMR
spectrum (CDCl3, δ, ppm): 2.35 (s, 3H, Me), 2.42 (s,
3H, Me), 7.11 (m, 1H, H5), 7.26 (m, 2H, H4,6), 7.35
(m, 1H, H2).
S-(4-methylphenyl) thioacetate (7): yield 15.0 g
Synthesis of S-Esters of Thiocarboxylic Acids
20
20
(90%), bp 76°C (0.5 mmHg),
1.5635,
1.0871.
d4
nD
IR spectrum (thin film, ν, cm–1): 1712 (C=O).
A mixture of an aliphatic or aromatic thiol
(0.1 mol) and a carboxylic acid chloride (0.2 mol) was 1H NMR spectrum (CDCl3, δ, ppm): 2.37 (s, 3H,
heated for 4 h at 60°C; after cooling, it was diluted with
60 mL of benzene, washed with a saturated solution of
NaHCO3 (4 × 30 mL), and dried over MgSO4. The
desired products were isolated by the fractionation of
the residue under atmospheric pressure (compounds 1
and 2) or in a vacuum (compounds 3–19).
Me), 2.41 (s, 3H, Me), 7.25 (m, 4H, Ar).
S-(3-methoxyphenyl) thioacetate (8): yield 12.0 g
(66%), bp 105°C (1 mmHg), 20 1.5606, 20 1.1596. IR
nD
d4
spectrum (thin film, ν, cm–1): 1718 (C=O). 1H NMR
spectrum (CDCl3, δ, ppm): 2.40 (s, 3H, Me), 3.63 (s,
3H, MeO), 6.71 (m, 1H, H2), 7.11 (m, 1H, H4,6), 7.28
S-n-propyl thioacetate (1): yield 9.7 g (82%), bp
136°C, 20 1.4556, 20 0.9793. IR spectrum (thin film,
(d, 3J 8.4 Hz, 1H, H5).
nD
d4
S-(4-methoxyphenyl) thioacetate (9): yield 14.1 g
(77%), bp 98°C (0.5 mmHg), 20 1.5721, 20 1.1586. IR
ν, cm–1): 1695 (C=O). 1H NMR spectrum (CDCl3, δ,
ppm): 0.92 (t, 3J 6.9 Hz, 3H, Me), 1.52 (m, 2H, CH2),
2.30 (s, 3H, Me), 2.87 (t, 3J 6.9 Hz, CH2S). 13C NMR
spectrum (CDCl3, δ, ppm): 13.3 (Me), 22.7 (CH2),
30.5 (Me), 30.6 (CH2S), 194.0 (C=O).
nD
d4
spectrum (thin film, ν, cm–1): 1713 (C=O). 1H NMR
spectrum (CDCl3, δ, ppm): 2.38 (s, 3H, Me), 3.81 (s,
3
3H, MeO), 6.93 (d, J 8.8 Hz, 2H, H3,5), 7.31 (d,
3J 8.8 Hz, 2H, H2,6).
S-isopropyl thioacetate (2): yield 9.5 g (81%), bp
127°C, 20 1.4548, 20 0.9755. IR spectrum (thin film,
S-(4-fluorophenyl) thioacetate (10): yield 15.3 g
(90%), bp 84–85°C (4 mmHg), 20 1.5452, 20 1.2100.
nD
d4
nD
d4
ν, cm–1): 1696 (C=O). 1H NMR spectrum (CDCl3, δ,
1
IR spectrum (thin film, ν, cm–1): 1721 (C=O). H
ppm): 1.09 (d, 3J 7.0 Hz, 6H, Me), 2.33 (s, 3H, Me),
2.93 (q, 3J 7.0 Hz, CHS). 13C NMR spectrum (CDCl3,
δ, ppm): 22.7 (Me), 30.6 (Me), 34.4 (CHS), 195.0
(C=O).
NMR spectrum (CDCl3, δ, ppm): 2.28 (s, 3H, Me),
6.67 (m, 2H, H3,5), 7.20 (m, 2H, H2,6). 13C NMR
spectrum (CDCl3, δ, ppm): 29.8 (Me), 116.7 (d, 3JCF
8.6 Hz, C3,5), 124.5 (d, 4JCF 3.5 Hz, C1), 137.1 (d, 2JCF
22.2 Hz, C2,6), 163.2 (d, JCF 249.2 Hz, C4), 193.2
1
S-benzyl thioacetate (3): yield 15.4 g (93%), bp
20
20
(C=O).
84°C (2 mmHg),
1.5409,
1.1843. IR spectrum
d4
nD
(thin film, ν, cm–1): 1696 (C=O). 13C NMR spectrum
(CDCl3, δ, ppm): 30.2 (Me), 33.3 (CH2), 127.8 (C4),
129.2 (C2,6), 129.5 (C3,5), 138.9 (C1), 198.1 (C=O).
S-(4-chlorophenyl) thioacetate (11): yield 16.8 g
(90%), bp 108°C (3 mmHg), mp 36°C. IR spectrum
1
(KBr, ν, cm–1): 1721 (C=O). H NMR spectrum
(CDCl3, δ, ppm): 2.42 (s, 3H, Me), 7.28–7.33 (m,
S-phenyl thioacetate (4): yield 12.0 g (79%), bp
85°C (3.5 mmHg), 20 1.5706, 20 1.1218. IR spectrum
4H, Ar).
nD
d4
S-(4-bromophenyl) thioacetate (12): yield 20.3 g
(88%), bp 96°C (1 mmHg), mp 53°C. IR spectrum
(thin film, ν, cm–1): 1717 (C=O). 1H NMR spectrum
(CDCl3, δ, ppm): 2.30 (s, 3H, Me), 7.40 (s, 5H, Ph).
1
(KBr, ν, cm–1): 1722 (C=O). H NMR spectrum
13C NMR spectrum (CDCl3, δ, ppm): 29.7 (Me),
(CDCl3, δ, ppm): 2.42 (s, 3H, Me), 7.27 (d, 3J 8.5 Hz,
128.2 (C4), 129.0 (C1), 128.9 (C3,5), 134.2 (C2,6), 192.0
(C=O).
2H, H2,6), 7.54 (d, 3J 8.5 Hz, 2H, H3,5).
S-(4-iodophenyl) thioacetate (13): yield 23.3 g
(78%), mp 56°C. IR spectrum (KBr, ν, cm–1): 1722
(C=O). 1H NMR spectrum (CDCl3, δ, ppm): 2.42 (s,
S-(2-methylphenyl) thioacetate (5): yield 14.0 g
d420
20
(84%), bp 90–92°C (3 mmHg), nD 1.5610,
1.0518. IR spectrum (thin film, ν, cm–1): 1716 (C=O).
1H NMR spectrum (CDCl3, δ, ppm): 2.34 (s, 3H,
Me), 2.43 (s, 3H, Me), 7.21 (m, 1H, Ar), 7.30 (m, 2H,
3
3H, Me), 7.13 (d, J 6.7 Hz, 2H, H3,5), 7.74 (d,
3J 8.5 Hz, 2H, H2,6).
S-phenyl thiotrichloroacetate (14): yield 24.0 g
3
Ar), 7.39 (d, J 7.4 Hz, 1H, Ar). 13C NMR spectrum
(94%), bp 118°C (2 mmHg), mp 55°C. IR spectrum
1
(CDCl3, δ, ppm): 20.6 (Me), 30.1 (Me), 126.5, 127.4, (KBr, ν, cm–1): 1717 (C=O). H NMR spectrum
(CDCl3, δ, ppm): 7.40 (s, 5H, Ph). 13C NMR spec-
130.0, 130.7, 135.8 (C1,3–6), 141.9 (C2), 193.6 (C=O).
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FUNGICIDAL ACTIVITY OF S-ESTERS OF THIOCARBOXYLIC ACIDS
101
trum (CDCl3, δ, ppm): 94.7 (C), 125.5 (C4), 129.0
(C3,5), 129.8 (C1), 134.0 (C2,6), 185.9 (C=O).
BKM F-1119, Hormoconis resinae BKM F-1701, Pen-
icillium chrysegenum Thom BKM F-245, Chaciomium
globosum BKM D-109, and Trichoderma viride BKM
F-1127. In addition, yeasts Candida tropicalis Y-2771
were used as well. Meat peptone agar (MPA) was used
as the culture medium for the cultivation of bacterial
cultures, while wort agar (WA) was used for fungi and
yeasts.
S-(4-fluorophenyl) thiochloroacetate (15): yield
nD20
d420
1.5660,
18.8 g (92%), bp 108°C (2 mmHg),
1.3626. IR spectrum (thin film, ν, cm–1): 1721 (C=O).
1H NMR spectrum (CDCl3, δ, ppm): 4.17 (s, 2H,
CH2Cl), 7.02 (m, 2H, H3,5), 7.30 (m, 2H, H2,6). 13C
NMR spectrum (CDCl3, δ, ppm): 48.5 (CH2Cl),
117.2 (d, 3JCF 8.0 Hz, C3,5), 123.0 (d, 4JCF 2.2 Hz, C1),
137.7 (d, 2JCF 22.0 Hz, C2,6), 164.3 (d, 1JCF 248.2 Hz,
C4), 192.3 (C=O).
Investigation of Antimicrobial Properties
The antimicrobial properties of the synthesized
compounds were investigated by the agar well diffu-
sion method using suspensions of various cultures of
microorganisms according to GOST 9.052-88 “Uni-
fied System of Corrosion and Ageing Protection: Oils
and Greases: Laboratory Test Methods for Mould
Resistance”, GOST 9.082-77 “Unified System of
Corrosion and Ageing Protection: Oils and Lubri-
cants: Methods of Laboratory Tests for Resistance to
Bacteria Action”, GOST 9.023-74 “Unified System of
Corrosion and Ageing Protection: Oil Fuels: Method
of Laboratory Testing Biostability of Fuels Protected
by Antimicrobial Additives”, and GOST 9.085-78
“Unified System of Corrosion and Ageing Protection:
Cooling Lubricants: Bioresistance Test Methods.”
The prepared inoculating suspensions of two indi-
vidual bacterial cultures were mixed together in equal
volumes and used for infecting the samples. The shelf
life of the bacterial suspensions for inoculation should
be no more than four to six hours from the moment of
their preparation. A mixture of fungi was prepared in a
similar manner. When conducting the study, a culture
medium was poured into a Petri dish in the amount of
20–30 mL and allowed to solidify. To identify the zone
of growth inhibition of microorganisms and for the
arrangement of the samples of oils without a biocide
and with organic compounds, four to six wells were
prepared, which were “opened” on the surface of the
solidified culture medium by a sterile drill with a
diameter of 10 mm to the depth of 4–6 mm.
S-phenyl thiobutyrate (16): yield 14.6 g (81%), bp
120–121°C (9 mmHg). IR spectrum (thin film, ν,
1
cm–1): 1709 (C=O). H NMR spectrum (CDCl3, δ,
ppm): 0.99 (t, 3J 7.2 Hz, 3H, Me), 1.76 (m, 2H, CH2),
2.64 (t, 3J 7.2 Hz, 2H, CH2S), 7.41 (s, 5H, Ph).
S-phenyl thioisobutyrate (17): yield 15.7 g (88%),
20
20
bp 92°C (2 mmHg),
1.5300,
1.1246. IR spec-
d4
nD
trum (thin film, ν, cm–1): 1721 (C=O). H NMR
1
3
spectrum (CDCl3, δ, ppm): 1.26 (d, J 6.9 Hz, 6H,
Me), 2.83 (t, 3J 6.9 Hz, H, CH), 7.40 (s, 5H, Ph).
S-(4-fluorophenyl) thiopivalate (18): yield 15.4 g
20
(68%), bp 89°C (1 mmHg), 20 1.5176,
1.0851. IR
nD
d4
spectrum (thin film, ν, cm–1): 1154 (C–F), 1709
(C=O). 1H NMR spectrum (CDCl3, δ, ppm): 1.25 (s,
9H, Me), 6.60 (m, 2H, H3,5), 7.13 (m, 2H, H2,6). C
13
NMR spectrum (CDCl3, δ, ppm): 27.5 (Me), 47.3
(C), 116.7 (d, 3JCF 8.6 Hz, C3,5), 124.5 (d, 4JCF 2.5 Hz,
C1), 137.7 (d, 2JCF 21.2 Hz, C2,6), 163.9 (d, 1JCF 244.2
Hz, C4), 203.4 (C=O).
S-(4-fluorophenyl) thiobenzoate (19): yield 19.7 g
(85%), bp 162°C (3 mmHg), mp 50–51°C. IR spec-
1
trum (KBr, ν, cm–1): 1153 (C–F), 1721 (C=O). H
NMR spectrum (CDCl3, δ, ppm): 7.02 (m, 2H, H3,5,
Ar), 7.35 (s, 5H, Ph), 7.37 (m, 2H, H2,6). 13C NMR
spectrum (CDCl3, δ, ppm): 116.3 (d, 3JCF 8.6 Hz, C3,5,
The samples which were unaffected by microor-
ganisms are considered as almost not susceptible to
microbiological deterioration. The growth of the test
cultures and suppression zones were assessed in milli-
meters. The efficiency of the antimicrobial action of
the additives being used was assessed by the value of
the diameter of the zone of growth suppression of bac-
teria and fungi around the well with an additive.
4
Ar), 123.2 (d, JCF 3.5 Hz, C1, Ar), 127.5 (C3,5, Ph),
128.6 (C2,6, Ph), 133.5 (C4, Ph), 136.8 (C1, Ph), 137.2
(d, 2JCF 22.0 Hz, C2,6, Ar), 163.2 (d, 1JCF 249.0 Hz, C4,
Ar), 189.9 (C=O).
The synthesized organic compounds were intro-
duced into the samples of fuel blends at a concentra-
tion of 0.01–1.0 wt %.
The tests were performed on jet fuels of the T-1 and
TS-1 brands, a cooling lubricant (CL) of the IKhP-
45E brand, and a diesel oil of the D-11 brand (in a pure
Strains of Microorganisms and Cultivation Conditions
A mixture of Pseudomonas aeruginosa BKM B-588 state and in a blend with additives 10% IKhP-101 +
and Mycobacterium lacticolium BKM B-355 pure bac- 2% SB-3 + 0.5% AzNII depressant + 0.003% PMS-
terial cultures was used for the tests because they are 200A) under the conditions mimicking tropical condi-
the most powerful destroyers of petroleum products. tions (at 28–32°C and a relative air humidity of 90–
Pure cultures of the following fungal species were used 100%) with an exposure of 30 days per experimental
in the test for fungicidal activity: Aspergillus niger run; the growth of the test cultures was recorded every
PETROLEUM CHEMISTRY Vol. 59 No. 1 2019

102
ALIEV et al.
ten days. The experiments were conducted in tripli- the antimicrobial activity of these compounds against
cates. The biocidal properties of the thioesters in avia- Cladosporium resinae is higher than that of 8-hydroxy-
tion gasoline were compared with those of the known quinoline. Electron-donating substituents have the
antimicrobial additive 8-hydroxyquinoline, which is opposite effect. In passing from thioacetic to thiopiv-
generally used in fuel and lubricating oil formulations. alic acid (R = t-Bu), the degree of bactericidal and
Hexachlorophene was used as the reference material fungicidal action sharply decreases (compare com-
in the IKhP-45E cooling lubricant.
pounds 10 and 18). It follows from the comparison of
the antimicrobial activity of the thioesters of butyric
and isobutyric acids (compounds 16 and 17) that
compounds containing unbranched radicals exhibit
stronger fungicidal activity than their structural iso-
mers.
The bactericidal and fungicidal activities of S-aryl
thiobenzoates are very weak, being approximately the
same as those of phenylacetone (compare 19 and 20).
RESULTS AND DISCUSSION
To perform the tests, S-esters of thiocarboxylic
acids 1–19 with substituents of different natures in the
thiol and carboxylate moieties have been synthesized.
The reactions were carried out in the absence of cata-
lysts and condensing agents according to a procedure
described in [11, 12].
It has been found during the study that the general
toxicity and selectivity of the action of aryl thioesters
ArSC(O)Me depends on the character and position of
the substituent in the arylthio group. Thus, the F, Cl,
Me, and MeO substituents on the benzene ring
increase the fungicidal activity of S-aryl thioacetates.
Isomeric S-fluorophenyl and S-methylphenyl thioac-
etates are arranged in the following order of antimicro-
bial activity: para- > meta- > ortho-. para-Methyl-,
methoxy-, and chloro-substituted aryl thioesters are
comparable with the reference 8-hydroxyquinoline
(antimicrobial agent Oxine), in fungicidal activity
(Table 1).
Table 2 presents the results of testing the most
active S-aryl thioacetates for antimicrobial activity in
the IKhP-45E cooling lubricant. It was preliminarily
found that introducing S-esters of thiocarboxylic acids
into IKhP-45E does not alter its physicochemical
properties and performance characteristics. It has
been shown that all the studied compounds inhibit
both bacterial and fungal cultures. Compound 9
turned out to be the most active; its microbial growth
inhibition zone is substantially larger than that of the
reference material.
Also, experiments (in a preliminary version) on the
investigation of the antimicrobial activity of four esters
of thioacetic 3, 6, and 7 and thiotrichloroacetic 14
acids in a D-11 diesel oil were conducted (Table 3).
Compounds 3, 6, 7, and 14 at a concentration of
1 wt % exhibit high fungicidal activity.
A similar result was obtained when introducing
additives to the diesel oil formulation with antioxi-
dant, sulfonate, and silicon additives with the
following composition: D-11 oil + 10% IKhP-101 +
2% SB-3 + 0.5% AzNII depressant + 0.003% PMS-
200A.
Introducing thioesters to the formulation render it
resistant to microbiological deterioration with pre-
serving their physicochemical properties for a long
period of time (Table 3).
O
60°C, 4 h
−HCl
R1SC(O)R2
65 93%
R1SH + R2
C
Cl
−
The structure of synthesized compounds 1–19 has
been confirmed by spectral data which are in agree-
ment with the published data [11, 12]. There are
intense bands at 1580, 1480, and 3040–3100 cm–1 in
the IR spectra of S-organyl thiocarboxylates which are
due to stretching vibrations of the C=C and =C–H
bonds in the benzene ring. The band at 820 cm–1 char-
acterize out-of-plane vibrations of CH in the 1,4-sub-
stituted benzene ring. The stable wavenumber band at
1153 cm–1 in the spectra of 4-fluorophenyl thiocar-
boxylates is due to C–F stretching. The stretching
vibrations of the C=O bond manifest themselves as an
asymmetric band with a maximum at 1696 cm–1 (in the
case of alkyl thioacetates 1–3) and 1709–1722 cm–1 (in
the case of aryl thiocarboxylates 4–19).
The performed tests give evidence for the fact that
all the studied S-esters of thiocarboxylic acids inhibit
the growth of fungi and bacteria in the T-1 and TS-1
fuels (Table 1).
In antimicrobial activity, S-alkyl thioacetates (1–3)
are noticeably inferior to S-aryl thioacetates (4–13).
The latter exhibit pronounced bactericidal and fungi-
cidal properties. Here, it has been found that the anti-
microbial activity of the studied compounds is due to
the presence of the ArSC(O) group because their car-
bon-containing PhCH2C(O)Me (20) and oxygen-
containing 4-FC6H4OC(O)Me (21) analogues have
low activity against the microorganisms under study. A
significant decrease in antimicrobial activity has also
been noted in the case of the replacement of the aryl
radical MeC6H4 (in compounds 6 and 7) by the aryl-
alkyl radical C6H5CH2 (in compound 3), with of the
total number of carbon atoms being the same. The
antimicrobial properties of thioesters ArSC(O)R sub-
stantially depend on the nature of the thiocarboxylic
acid. Introducing electron-withdrawing substituents
There are no published data on the mechanism of
into the carbonyl group (compounds 14 and 15) leads antimicrobial action of aryl esters of thioacetic acid or
to a 1.5–2.0-fold increase in the fungicidal activity; compounds that are structurally similar to them.
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FUNGICIDAL ACTIVITY OF S-ESTERS OF THIOCARBOXYLIC ACIDS
Table 1. Antimicrobial activity of S-aryl esters of thiocarboxylic acids1
103
Diameter of growth inhibition zone for test cultures, mm
Compound no.
Structural formula
bacterial mixture (MPA)
fungal mixture (WA)
1
2
3
n-PrSC(O)Me
i-PrSC(O)Me
PhCH2SC(O)Me
PhSC(O)Me
12
11
13
16
16
19
21
18
20
20
26
11
15
26
19
11
8
13
11
15
25
24
28
35
25
32
27
31
17
19
35
40
20
6
4
5
2-MeC6H4SC(O)Me
3-MeC6H4SC(O)Me
4-MeC6H4SC(O)Me
3-MeOC6H4SC(O)Me
4-MeOC6H4SC(O)Me
4-FC6H4SC(O)Me
4-ClC6H4SC(O)Me
4-BrC6H4SC(O)Me
4-IC6H4SC(O)Me
PhSC(O)CCl3
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
4-FC6H4SC(O)CH2Cl
PhSC(O)Pr-n
PhSC(O)Pr-i
4-FC6H4SC(O)Bu-t
4-FC6H4SC(O)Ph
PhCH2C(O)Me
7
4
6
5
8
6
4-FC6H4OC(O)Me
14
29
13
24
+
8-Hydroxyquinoline (reference)
TS-1 fuel (without additives)
2
+
1
2
The additive concentration in T-1 is 0.25 wt %. + means the absence of inhibition zone.
Table 2. Antimicrobial activity of S-aryl thioacetates in the IKhP-45E cooling lubricant1
Diameter of growth inhibition zone
Biocide
for microorganisms, mm
compound no.
structure
PhSC(O)Me
bacteria
fungi
4
32
40
46
24
40
30
26
24
50
48
28
7
4-MeC6H4SC(O)Me
4-MeOC6H4SC(O)Me
4-FC6H4SC(O)Me
4-ClC6H4SC(O)Me
9
10
11
2
Hexachlorophene (reference)
+
IKhP-45E
+
+
1
2
The additive concentration is 0.25 wt %. + means the absence of inhibition zone.
PETROLEUM CHEMISTRY Vol. 59 No. 1 2019

104
ALIEV et al.
Table 3. The antimicrobial action of S-aryl thioacetates in a diesel oil 1
Diameter of the zone of growth suppression
of microorganisms, mm
Oil
S-aryl thioacetate
bacteria
fungi
44
2
D-11
PhCH2SC(O)Me (3)
+
Formulation
D-11
Formulation
D-11
Formulation
D-11
Formulation
+
+
44
46
40
50
46
42
42
3-MeC6H4SC(O)Me (6)
4-MeC6H4SC(O)Me (7)
30
36
24
12
12
PhSC(O)CCl3 (14)
1
2
The concentration of the biocide additive is 1.0 wt %. + means the absence of inhibition zone.
According to some authors [13], the antimicrobial
properties of the aryl esters of alkanethiosulfonic acids
RSO2R1 which are structurally similar to the thioesters
CONCLUSIONS
The antimicrobial activity of a series of S-esters of
thiocarboxylic acids was studied. The analysis of the
structure–activity relationship showed that S-aryl
esters of thioacetic acid containing a Cl, MeO, or Me
RC(O)R1 are explained by their ability to react with
thiol compounds of the cysteine type, which are vital
for many microorganisms, leading to the “blockage” group in the para-position on the benzene ring possess
of their sulfhydryl groups and causing violation of the highest activity. These compounds are comparable
with the reference 8-hydroxyquinoline in fungicidal
activity and can be recommended as biocide additives
to petroleum products.
The tests of the cooling lubricant IKhP-45E CL
with the additives of thioesters were performed. It was
shown that these additives inhibit the growth of all the
studied microorganisms; however, their activity
against fungi is higher.
Experiments on the investigation of compatibility
of some of the additives with oils were also performed.
The thioesters impart stability to these oils against
microbiological deterioration with preserving their
physicochemical properties for a long period of time.
metabolic processes of a bacterial cell. As is known,
some enzymes lose their activity (reversibly or irre-
versibly) when treated with substances reacting with
the sulfhydryl group. Such enzymes include, e.g.,
papain, urease, succinic acid dehydrogenase, and
some enzymes involved in the metabolism of proteins
and lipids (transaminase, d-aminooxidase, etc.) as
well as carbohydrates (carboxylase). It was shown that
the activity of such enzymes is tightly related to the
presence of free sulfhydryl groups in their molecules;
it is the disabling of these groups that leads to the inac-
tivation of an enzyme, while animal cells are partially
protected by glutathione present in them [14]. Some
researchers reduce the mechanism of antibiotic action
of allicin and its synthetic analogues, as well as other
antibiotics capable of interacting with the sulfhydryl
groups of cysteine, to this particular type of inactiva-
tion of bacterial enzymes [15].
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Translated by E. Boltukhina
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