Synthesis and antioxidative activity of S-substituted 2-mercapto-1,4- dihydroxybenzenes

Article abstract of DOI:10.1023/B:RJAC.0000038812.89494.22

S-Substituted 2-mercapto-1,4-dihydroxybenzenes were prepared, and their antioxidative activity in autooxidation of cumene and in the reactions with cumylperoxy radicals and cumyl hydroperoxide was studied.

Full text of DOI:10.1023/B:RJAC.0000038812.89494.22

Russian Journal of Applied Chemistry, Vol. 77, No. 5, 2004, pp. 783 786. Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 5,
2004, pp. 787 790.
Original Russian Text Copyright
2004 by Farzaliev, Allakhverdiev, Shamkhalova, Rzaeva.
ORGANIC SYNTHESIS
AND INDUSTRIAL ORGANIC CHEMISTRY
Synthesis and Antioxidative Activity
of S-Substituted 2-Mercapto-1,4-dihydroxybenzenes
V. M. Farzaliev, M. A. Allakhverdiev, S. A. Shamkhalova, and I. A. Rzaeva
Kuliev Institute of Chemistry of Additives, National Academy of Sciences of Azerbaijan, Baku, Azerbaijan
Baku State University, Baku, Azerbaijan
Received August 4, 2003; in final form, January 2004
Abstract S-Substituted 2-mercapto-1,4-dihydroxybenzenes were prepared, and their antioxidative activity
in autooxidation of cumene and in the reactions with cumylperoxy radicals and cumyl hydroperoxide was
studied.
Sulfur-substituted phenols as effective oxidation
inhibitors are widely used for stabilization of petrole-
um products [1]. Their high inhibiting performance is
due to the presence in one molecule of two functional
groups: phenolic hydroxyl and sulfide sulfur, making
these compounds capable to inhibit oxidation by scav-
enging of peroxy radicals and decomposition of per-
oxides [2, 3].
R = (CH ) CH, X = Br (IV); R = CH COOH, X =
3 2
2
Cl (V); R = CH CO, X = Br (VI); R = CH =CHCH ,
3
2
2
X = Br (VII); R = C H CH , X = Cl (VIII).
6
5
2
S-tert-Butyl (IX) and S-(2-cyanoethyl) (X) deriva-
tives of I were prepared, respectively, by addition of I
to acrylonitrile in the presence of triethylamine and to
2-methylpropene in the presence of catalytic amounts
of sulfuric acid:
Proceeding with studies on synthesis of phenolic
sulfides [2 7], we prepared S-substituted 2-mercapto-
1,4-dihydroxybenzenes and studied their antioxidative
activity in cumene oxidation.
OH
SCH2CH2CN,
CH =CHCN
2
2-Mercapto-1,4-dihydroxybenzene I was prepared
as follows:
X
OH
OH
O
OH
OH
I
SSO3Na
SC(CH3)3.
SH
CH =C(CH )
2
3 2
[H]
+ Na2S2O3
.
IX
O
OH
OH
OH
I
The purity of the compounds was checked by TLC
and elemental analysis (Table 1), and their structures
were proved by IR and H NMR spectroscopy.
S-Methyl (II), S-ethyl (III), S-isopropyl (IV),
S-carboxymethyl (V), S-acetyl (VI), S-allyl (VII),
and S-benzyl (VIII) derivatives of I were prepared
by the reactions of I with the corresponding halides in
the presence of NaOH:
1
The IR spectra of I X contain absorption bands
at about 1450 (C C stretching vibrations in the aro-
matic ring), 3450 (stretching vibrations of the O H
bond involved in hydrogen bonding with the adjacent
OH
1
S atom [8]), and 810 860 cm (1,2,4-substituted
SR
NaOH
1
benzene ring). The H NMR spectra of mercaptophen-
I + RX
,
_
NaX
ols I X contain a proton signal from two hydroxy
groups (7.4 ppm). The multiplets of three benzene
ring protons are observed at about 5.9 ppm. Com-
OH
_
II VIII
where R = CH , X = I (II); R = C H , X = Br (III);
1
pound I exhibits a band at 2530 cm in the IR spec-
3
2 5
1070-4272/04/7705-0783 2004 MAIK Nauka/Interperiodica

784
FARZALIEV et al.
Table 1. Yields, melting points, retention factors (Rf), and elemental analyses of I X
Found, %
Calculated, %
H
Com-
pound
mp,
C
Yield, %
Rf
Formula
C
H
S
C
S
I
II
117 117.5
123 124
135 136
142 143
147 148
140 142
99 100
132 133
97 98
148 149
38
47
35
42
55
49
60
26
75
36
0.57
0.82
0.63
0.47
0.73
0.87
0.68
0.85
0.57
0.90
50.83
53.49
56.21
57.83
60.73
50.72
52.37
59.12
55.52
67.43
4.07
5.28
5.75
5.62
7.41
4.17
4.61
5.74
4.19
5.39
22.36 C6H6O2S
20.32 C7H8O2S
20.66 C8H10O2S
17.23 C9H12O2S
16.38 C10H14O2S
15.27 C9H8O2S
17.59 C8H8O3S
17.39 C9H10O2S
16.58 C9H9NO2S
13.67 C13H12O2S
50.68
53.82
56.45
58.67
60.57
50.94
52.16
59.32
55.37
67.25
4.25
5.16
5.92
6.56
7.12
3.79
4.38
5.53
4.65
5.21
22.55
20.51
20.49
17.40
16.17
15.11
17.41
17.60
16.42
13.80
III
IV
V
VI
VII
VIII
IX
X
trum (S H stretching vibrations), and its NMR spec-
trum contains an SH proton singlet at 3.3 ppm. The
IR and H NMR spectra of II X exhibit features
terminated on one molecule of an inhibitor and its
transformation products:
1
characteristic of the substituents at the S atom.
f = indvind/[In]0,
To evaluate the inhibiting activity of I X, we used
as model substrate cumene, as the mechanism of its
oxidation is well understood. Experiments on cumene
autooxidation in the presence of I X revealed their
fairly high inhibiting performance. Experiments on
oxidation of cumene initiated with azobis(isobutyro-
where
is the induction period; v , initiation rate;
ind
ind
0
and [In] , initial concentration of inhibitor In.
From the kinetics of the oxygen uptake, we calcu-
lated the rate constants of the reactions of the inhibit-
ors with peroxy radicals k [8, 9]. To do this, we
7
2
nitrile) (AIBN; 60 C, [AIBN] = 2 10 M) showed
transformed the kinetic curves of the oxygen uptake
1
that these compounds actively terminate oxidation
chains, reacting with cumylperoxy radicals. Data for I
as example are shown in Fig. 1. From the induction
from the coordinates [O ] to the coordinates [O ]
2
2
1
and from the slope tan , equal [9, 10] to
period
, we calculated the stoichiometric inhibition
tan = fk7[In]0/(k2[RH]vind),
ind
coefficient f equal to the number of oxidation chains
found the constant k :
7
4
1/
10
k7 = tan k2[RH]vind/f[In]0,
1/VO2
VO2
ml
,
102
where k is the rate constant of chain initiation [9, 10],
2
1
1
equal to 1.51 l mol s ; [RH] = 6.9 M.
Table 2 shows that the constants k for the com-
7
pounds with electron-donor substituents are higher
compared to the compounds with electron-acceptor
substituents. As for f, it varies in the range 1.05 2.20.
Reactions of I X with cumyl hydroperoxide (CHP)
were performed in chlorobenzene under nitrogen at
110 C. All the compounds I X decompose CHP.
Figure 2 shows (by the example of I) that the kinetic
curve of CHP decomposition in the presence of mer-
captophenols is S-shaped, which is typical of auto-
catalytic processes. The reaction starts with a certain
induction period in which the consumption of CHP is
insignificant; this is followed by fast catalytic decom-
, min
Fig. 1. Kinetic curves of O uptake in initiated oxidation of
cumene (1) without additives and (2) in the presence of I.
(3) Linearization of curve 2 in the coordinates 1/ 1/V
(V ) Volume of oxygen taken up and ( ) time.
2
.
O
2
O
2
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SYNTHESIS AND ANTIOXIDATIVE ACTIVITY
785
position of CHP and then by reaction deceleration due
to a decrease in the CHP concentration. Apparently,
the inhibitor first reacts with CHP to give a product
that catalytically decomposes CHP.
Table 2. Kinetic parameters of the reactions of mercapto-
phenols I X with cumylperoxy radicals k7 and f (60 C,
[AIBN] = 2 10 M) and of decomposition of cumyl
2
hydroperoxide k and
(110 C)
To determine the reaction order, we studied how
the initial rate of the catalytic decomposition of CHP
depends on the concentrations of the reactants. We
4
Com-
pound
k7 10 ,
k,
f
l mol 1 s
l mol 1 s
1
1
found that the initial rate v of catalytic decomposition
of CHP under the action of I X obeys the kinetic
equation
0
I
II
2.15
1.53
1.71
2.70
1.52
2.17
1.05
1.41
1.25
1.15
1.27
2.20
2.11
1.92
1.05
1.72
1.64
1.57
1.62
1.74
10.45
3.24
2.45
1.96
1.62
2.99
3.50
3.10
4.63
4.67
4500
3350
2730
1840
400
2800
1770
1050
1500
2870
III
IV
V
VI
VII
VIII
IX
X
v0 = k[In][ROOH]2.
To determine the reaction stoichiometry, we took
CHP in excess. The catalytic factor
characterizes
the number of CHP molecules decomposed with one
inhibitor molecule; it was calculated by the formula
= [ROOH]0
[ROOH] /[In]0,
2,5-Dihydroxyphenyl methyl sulfide II. A 2-g
portion of NaOH was added at 10 15 C to a solution
of 7.1 g (0.05 mol) of I in 30 ml of isopropyl alcohol,
after which 7.1 g of methyl iodide was added at the
same temperature. The reaction was performed under
nitrogen. The temperature was raised to 60 C, after
which the mixture was stirred for an additional 3 h
and washed first with 2 M HCl and then with water to
neutral reaction. The organic layer was treated with
petroleum ether (30 60 C) and dried over sodium
sulfate.
where [ROOH] and [ROOH] are, respectively, the
0
initial and final concentrations of [CHP], and [In] is
0
the initial inhibitor concentration.
Experiments showed that one molecule of I X can
decompose up to several thousands of CHP molecules
(Table 2). The kinetic parameters of the reaction show
certain correlation with the properties of substituents
at the S atom. In particular, in going to branched alkyl
substituents (compounds II V) k decreases, probably
owing to steric factors; is higher for the compounds
with electron-donor substituents at the S atom.
Compounds III, IV, VII, VIII, and X were pre-
pared similarly.
EXPERIMENTAL
2,5-Dihydroxyphenyl tert-butyl sulfide IX.
A 3-ml portion of isobutylene was added to a mixture
of 7.1 g of I and five drops of concentrated H SO
The IR spectra were recorded on a Specord 75-IR
2
4
1
saturated with (NH ) SO , heated to 110 120 C.
spectrophotometer, and the H NMR spectra, on a
4 2
4
Then the mixture was neutralized with 13 ml of 2 M
NaOH, treated with petroleum ether, and washed three
Varian T-60 spectrometer, with tetramethylsilane as
internal reference.
2-Mercapto-1,4-dihydroxybenzene I. A solution
of 43.2 g of benzoquinone in 150 ml of glacial acetic
acid was heated to 40 50 C, and then a solution of
150 g of Na S O in 200 g of water was gradually
[ROOH], M
2 2
3
added, avoiding warming-up of the reaction mixture
by more than 10 C. After short stirring, the transpar-
ent and almost colorless solution was saturated with
KCl to precipitate sodium S-(2,5-dihydroxyphenyl)
thiosulfate. A solution of 2.6 g of this salt in 10 ml of
water was mixed with 20 ml of concentrated HCl, and
5 g of zinc dust was gradually added; the reaction
temperature was maintained at 40 50 C until the gas
evolution ceased.
, min
Fig. 2. Kinetic parameters of decomposition of cumyl hy-
droperoxide (ROOH) under the action of I. [In] = 3 10
4
,
[ROOH] = 0.285 M. ( ) Time.
0
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 77 No. 5 2004

786
FARZALIEV et al.
times with water. After drying over Na SO , the sol-
REFERENCES
2
4
vent was distilled off.
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NaOH in 10 ml of water, and a concentrated solution
of 4.7 g of chloroacetic acid, neutralized with sodium
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2
4
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A mixture of 7.1 g of I, 20 ml of anhydrous benzene,
and a drop of triethylamine was stirred at 60 70 C for
3 h. Then the mixture was washed with water and
dried over Na SO . The solvent was distilled off, and
2
4
the product was recrystallized from diethyl ether.
CONCLUSIONS
(1) 2-Mercapto-1,4-dihydroxybenzene was pre-
pared and converted into various S-substituted deriva-
tives.
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(2) The compounds synthesized exhibit synergism
as inhibitors of cumene oxidation and, being poly-
functional antioxidants, terminate cumene oxidation
chains by reactions with peroxy radicals and catalyti-
cally decompose cumene hydroperoxide.
10. Emanuel’, N.M. and Denisov, E.T., Neftekhimiya,
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