Reactions of aminophenols with formaldehyde and hydrogen sulfide

Article abstract of DOI:10.1007/s11172-006-0254-7

The reaction of m-aminophenol with CH₂O and H₂S (1: 2: 1 ratio) afforded 2, 12-dioxa-4, 14-dithia-6, 16-diazatricyclo[15.3.1.1 ^7,11]docosa-1(20), 7(22), 8, 10, 17(21), 18-hexaene in ～9% yield. Aminophenol o-and p-isomers r

Full text of DOI:10.1007/s11172-006-0254-7

Russian Chemical Bulletin, International Edition, Vol. 55, No. 2, pp. 312—316, February, 2006
312
Reactions of aminophenols with formaldehyde and hydrogen sulfide
V. R. Akhmetova,a G. R. Nadyrgulova,a,b S. R. Khafizova,a T. V. Tyumkina,a A. A. Yakovenko,c M. Yu. Antipin,c
ꢀ
L. M. Khalilov,a R. V. Kunakova,b and U. M. Dzhemileva
aInstitute of Petrochemistry and Catalysis, Russian Academy of Sciences,
141 prosp. Oktyabrya, 450075 Ufa, Russian Federation.
Fax: +7 (347 2) 31 2750. Eꢀmail: ink@anrb.ru
bUfa State Institute of Service,
145 ul. Chernyshevskogo, 450077 Ufa, Russian Federation.
Fax: +7 (347 2) 52 0806. Eꢀmail: nis_utis@bashnet.ru
cA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (495) 135 9271. Eꢀmail: star@xray.ineos.ac.ru
The reaction of mꢀaminophenol with CH2O and H2S (1 : 2 : 1 ratio) afforded 2,12ꢀdioxaꢀ
4,14ꢀdithiaꢀ6,16ꢀdiazatricyclo[15.3.1.17,11]docosaꢀ1(20),7(22),8,10,17(21),18ꢀhexaene in
~9% yield. Aminophenol oꢀ and pꢀisomers react with CH2O and H2S (1 : 3 : 2) to form 2ꢀ and
4ꢀ[4Hꢀ1,3,5ꢀdithiazinꢀ5(6H)ꢀyl]phenols in 86 and 71% yields, respectively. In the crystal
structure of the latter, molecules contain dithiazine cycles in the chair conformation with the
axial hydroxyphenyl group. Molecular packing represents a combination of molecules forming
chains due to the OH...S intermolecular hydrogen bond.
Key words: thiomethylation; oꢀ, mꢀ, and pꢀaminophenols; formaldehyde; hydrogen sulfide;
Xꢀray diffraction analysis.
We have previously studied the multicomponent conꢀ
For example, the reaction of mꢀaminophenol (1) with
CH2O and H2S (1 : 2 : 1 ratio) in EtOH for 3 h at ~40 °C
affords a mixture of cyclic sulfides (Scheme 1) consisting
of 1,2,4ꢀtrithiolane (2), 1,2,4,6ꢀtetrathiepane (3), and sulꢀ
densation of aliphatic1 and aromatic2 primary amines,
amino acids,3,4 hydrazine,5 and their derivatives with H2S
and CH2O, affording predominantly substituted diꢀ
thiazines of different structure.
Continuing to study the liquidꢀphase condensation of
H2S and CH2O with compounds containing active hyꢀ
drogen atoms and to develop preparative methods for
syntheses of macrocyclic heterocycles and functionally
substituted dithiazines, we examined the reactions of biꢀ
functional monomers, viz., oꢀ, mꢀ, and pꢀaminophenols,
with H2S and CH2O.
Scheme 1
According to available data,6,7 sulfurꢀcontaining
macroheterocycles are promising as sensor systems for
detection of silver and gold ions and as selective extractꢀ
ing agents and sorbents of noble and rare metals.
Results and Discussion
Thiomethylation of anilines with H2S and CH2O is
known to form dithiazines and thiazetidines.2,8,9 In the
case of simple phenols, this process proceeds at the aroꢀ
matic ring.10 In the present work we found that thioꢀ
methylation of aminophenols depends on the mutual arꢀ
rangement of functional groups in the aromatic ring and
proceeds exclusively at these groups.
4: n = 1 (T = 40 °C, ~9% yield)
5: n = 7 (T = 20 °C, ~39% yield)
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 305—308, February, 2006.
1066ꢀ5285/06/5502ꢀ0312 © 2006 Springer Science+Business Media, Inc.

Reactions of aminophenols with CH2O and H2S
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 2, February, 2006
313
furꢀcontaining macroheterocycle 4 in an overall yield
of 40%.
The condensation of aminophenol 1 with CH2O and
H2S in a ratio of 1 : 3 : 2 affords poorly soluble oligomers,
whose identification is very difficult.
The structures of compounds 2 and 3 were proved by
comparing with authentic samples.11 The IR spectrum of
compound 4 exhibits intense bands at 710, 820, 1185,
1375, 1600, 2900, and 3300 cm–1, which indicates that
the heterocycle molecule contains the C—S, C—O,
CAr—O, CAr—N, and C=C (arom.) bonds and the CH2
and NH groups. The UV spectrum contains a resonance
peak at 297.6 nm (ε = 10) assigned to the band of the
n—π*ꢀtransition, which is characteristic of groups attached
to the aromatic ring and having a free electron pair.12 The
1H NMR spectrum of compound 4 exhibits multiplet sigꢀ
nals at δ 6.30—6.88 characteristic of the H atoms bonded
to the aromatic ring. Broadened singlets at δ 5.60 and 3.69
belong to the methylene protons arranged between the
S and O atoms and between S and N, respectively. The
13C NMR spectrum of compound 4 contains signals at
δ 111.03, 126.46, 128.07, 130.93, 148.93, and 155.83 beꢀ
longing to the C atoms of the aromatic ring and signals at
δ 46.38 and 62.97 attributed to the C atoms of the methylꢀ
ene groups localized between the S and N atoms and
between S and O, respectively. The mass spectrum of
product 4 contains no molecular ion peak but exhibits
peaks of ions of the characteristic residual fragments
with m/z 167 ([CH2NHC6H4OCH2S]+) and m/z 149
([C6H4NHCH2SC]+) and weak peaks of ions of fragꢀ
ments formed upon thermal decomposition in the mass
spectrometer evaporator (m/z 279, 258 [M – CS2]+, 247
and 207). Cryoscopic13 determinations give a value of
334 10 corresponding to the molecular weight of comꢀ
pound 4, whereas elemental analysis confirms the moꢀ
lecular formula C16H18N2O2S2 for this compound.
Basing on the experimental results obtained, we can
conclude that the molecule of compound 4 consists of
two aminophenol moieties symmetrically linked through
the bismethylenesulfide fragments. No linear oligomer is
Unlike mꢀaminophenol, its oꢀ and pꢀisomers (6 and 7)
undergo multicomponent condensation with H2S and
CH2O exclusively at the amino group to form dithiazines,
namely, 5ꢀ(2ꢀhydroxyphenyl)dihydroꢀ1,3,5ꢀdithiazine (8)
and 5ꢀ(4ꢀhydroxyphenyl)dihydroꢀ1,3,5ꢀdithiazine (9) in
86 and 71% yields, respectively (Scheme 2).
Scheme 2
pꢀDithiazinylphenol 9 has earlier14 been synthesized
by the condensation of NaSH, CH2O, and pꢀaminophenol
but the product was not characterized completely. We
1
proved the structures of compounds 8 and 9 by H and
13C NMR spectroscopy and mass spectrometry. In addiꢀ
tion, Xꢀray diffraction analysis was performed for comꢀ
pound 9. The mass spectra of products 8 and 9 exhibit the
molecular ion peak [M]+ with m/z 213. The fragmentaꢀ
tion directions differ for both compounds, although the
spectrum of each compound contains ions with m/z 167,
121, and 107, which are formed by the subsequent deꢀ
tachment of the CH2S, (CH2S)2, and CH2SCH2SCH2
fragments from the 1,3,5ꢀdithiazine rings. The 13C NMR
spectra of compounds 8 and 9 contain signals attributed
to the C atoms of the aromatic ring along with the characꢀ
teristic signals of the dithiazine ring (δ 33.79 and 57.50 (8),
δ 34.12 and 55.29 (9)). The chemical shifts and intensity
ratio of the observed signals for the dithiazine ring (δ 4.30
and 4.70 (8), δ 4.25 and 4.95 (9)) and the corresponding
signals of the H atoms of the aromatic ring in the 1H NMR
spectra of compounds 8 and 9 confirm the structures proꢀ
posed for these products.
1
formed under these conditions: the H and 13C NMR
spectra of compound 4 exhibit no signals of terminal
groups.
Thus, heterocycle 4 has a structure of 2,12ꢀdioxaꢀ
4,14ꢀdithiaꢀ6,16ꢀdiazatricyclo[15.3.1.17,11]docosaꢀ
1(20),7(22),8,10,17(21),18ꢀhexaene.
The overall yield of heterocycle 4 increases with an
increase in the total concentration of the starting reacꢀ
tants (mꢀaminophenol : CH2O : H2S = 1 : 2 : 1) in a
solution of 95% EtOH. However, along with the increase
in this yield, a mixture of other macrocyclic heteroꢀ
atomic compounds of the type 5 is formed, whose molꢀ
ecules contain two and more aminophenol moieties
(Mcr = 1333 10,13 the numerical average value of the
cyclooligocondensation degree is ~8). Solubility of such
oligomeric macroheterocycles is very low and, hence,
these compounds with unique structure are difficult to
isolate and purify.
The Xꢀray diffraction analysis of compound 9 showed
that dithiazine has a chair conformation with the axial
hydroxyphenyl group at the nitrogen atom. In crystal,
molecules of 9 are linked to form chains due to hydrogen
bonds O(1А)—H(10А)...S(2) and O(1)—H(10)...S(2B)
(Fig. 1). In addition to the latter, the crystal contains

314
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 2, February, 2006
Akhmetova et al.
S(1)
S(1B)
S(1A)
H(10)
S(2B)
H(10A)
O(1A)
H(10B)
S(2A)
S(2)
O(1B)
O(1)
Fig. 1. Geometry of 5ꢀ(4ꢀhydroxyphenyl)dihydroꢀ1,3,5ꢀdithiazine (9) molecules linked through the OH...S hydrogen bonds in
crystal.
weak intermolecular contacts S(1)...S(2) due to which
the chains form layers.
Experimental
Reaction products of thiomethylation of aminophenols were
analyzed by HPLC on an LKB chromatograph with a photoꢀ
metric detector at a wavelength of 238 nm. Separation was carꢀ
ried out by HPLC at ~20 °C on a metallic column 125×4 mm in
size (Separon SGX C18, grain size 5 µm) using an MeCN—H2O
Different reactivities of the isomeric aminophenols in
the reaction with H2S and CH2O are probably due to a
change in the basicity15 and acidity of the amino and
hydroxy groups in the composition of the starting phenols,
depending on their arrangement in the aromatic ring.
According to known data,16 the basicity of the amino
group (Kb) in aminophenols increases in the series
mꢀisomer < oꢀisomer < pꢀisomer, and the acidity of
the OH group (Ka) decreases in the order oꢀisomer >
> mꢀisomer > pꢀisomer (Table 1). Thus, of the three
aminophenols, only the mꢀisomer having the amino
group with the lowest basicity and the hydroxy group
with the sufficient acidity undergoes thiomethylation
by the action of CH2O and H2S simultaneously at both
functional groups to yield macroheterocycles 4 and 5.
However, oꢀaminophenol containing the hydroxy group
with the highest acidity does not undergo similar ring
closure, probably, due to the appearance of the inꢀ
tramolecular hydrogen bond OH...N.15 In the case of
the oꢀ and pꢀisomers, thiomethylation occurs only at
the amino group to form the corresponding dithiaziꢀ
nes 8 and 9.
(60 : 40) mixture as eluent, flow rate being 0.2 mL min–1
.
1H NMR spectra were recorded on Bruker AMꢀ300 (300 MHz)
and Tesla BSꢀ487 (80 MHz) spectrometers. 13C NMR spectra
were obtained on a JeolꢀFX 90Q spectrometer (22.50 MHz)
using Me4Si as the internal standard with CDCl3 or DMSOꢀd6
as solvents. The IR spectrum was recorded on a Specord 75 IR
spectrophotometer in a Nujol suspension. GCꢀMS analyses of
the compounds were carried out on a Finnigan 4021 instrument
(glass capillary column 50000×0.25 mm in size, HРꢀ5 stationary
phase, helium as carrier gas, temperature programming from 50
to 300 °C with a rate of 5 deg min–1, temperature of the injector
280 °C, temperature of the ion sources 250 °C, 70 eV). Elemenꢀ
tal analyses of the samples (C, H, N, O, and S) were conducted
on a Carlo Erba 1106 analyzer.17 Hydrogen sulfide was bubbled
and its consumption in mL was monitored using an ANPꢀ10
hose peristatic pump. Melting points were determined on an
PHMK 80/2617 instrument; TLC was carried out on Silufol
Wꢀ254 plates (developing with iodine vapor).
Reaction of mꢀaminophenol with H2S and CH2O. A solution
of mꢀaminophenol (1.09 g, 0.01 mol) in 95% EtOH (50 mL) was
added dropwise for 30 min at 40 °C to a solution of formaldeꢀ
hyde (37%, 1.47 mL, 0.02 mol) saturated with hydrogen sulfide
(224 mL, 0.01 mol). The mixture was stirred for 3 h at 40 °C,
To conclude, the direction of thiomethylation of isoꢀ
meric aminophenols with H2S and CH2O is determined
by the basicity and acidity of their functional groups.
Table 1. Influence of the aminophenol structure, reaction temperature, and ratio of the starting reactants on the yield and
composition of the reaction products
16
16
Aminophenol
Ka
Kb
Amine : CH2O : H2S
T/°C
Yield of reaction products (wt.%)
2
3
4
5
8, 9
1
6
1.4•10–10 1.5•10–10
1.4•10–10 1.5•10–10
2•10–10 5.2•10–10
2•10–10 5.2•10–10
2•10–10 5.2•10–10
2•10–10 5.2•10–10
5•10–11 32•10–10
5•10–11 32•10–10
5•10–11 32•10–10
5•10–11 32•10–10
1 : 2 : 1
1 : 2 : 1*
1 : 3 : 2
1 : 3 : 2
1 : 3 : 2
1 : 3 : 2
1 : 3 : 2
1 : 3 : 2
1 : 3 : 2
1 : 3 : 2
20
40
0
20
40
80
0
20
40
80
7
12
2
4
5
11
3
4
19
5
9
—
9
39
—
—
—
—
—
—
—
—
—
—
—
20
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
86
72
77
49
25
71
58
68
7
* The reaction was carried out with fivefold dilution in EtOH as compared to the previous entry (1 : 2 : 1, 20 °C).

Reactions of aminophenols with CH2O and H2S
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 2, February, 2006
315
and the precipitate that formed was filtered off. A mixture of
products 2—4 was separated by column chromatography on
SiO2 (hexane—AcOEt—CHCl3 (1.5 : 1 : 1) as eluent).
1,2,4ꢀTrithiolane (2).4,11 M.p. 74—75 °C, Rf 0.91. 13C NMR,
δ: 32.7 (s, C(3), C(5)). Mass spectrum, m/z (Irel (%)): 124 [M]+.
1,2,4,6ꢀTetrathiepane (3).4,11 M.p. 85—86 °C, Rf 0.76. Mass
spectrum, m/z (Irel (%)): 170 [M]+ (57); 124 [M – CH2S]+ (62);
78 [M – CH2SCH2S]+ (100); 45 [CHS]+ (55).
2,12ꢀDioxaꢀ4,14ꢀdithiaꢀ6,16ꢀdiazatricyclo[15.3.1.17,11]doꢀ
cosaꢀ1(20),7(22),8,10,17(21),18ꢀhexaene (4). The yield was
0.31 g (9%), m.p. 173—176 °C, Rf 0.54. Mcr = 334 10.
Found (%): C, 58.14; H, 5.83; N, 8.98; O, 9.66; S, 18.47.
5ꢀ(4ꢀHydroxyphenyl)dihydroꢀ1,3,5ꢀdithiazine (9). The yield
was 1.24 g (58%), m.p. 131—132 °C, Rf 0.57. Found (%):
C, 50.20; H, 5.60; N, 6.53; O, 7.64; S, 30.13. C9H11ONS2.
Calculated (%): C, 50.70; H, 5.20; N, 6.60; O, 7.50; S, 30.00.
1
IR, ν/cm–1: 690, 830, 1100, 1220, 1600, 2930, 3300. H NMR
(DMSOꢀd6), δ: 4.25 (br.s, 2 H, C(2)H2); 4.95 (br.s, 4 H, C(4)H2,
C(6)H2); 6.82 (d, 2 H, C(8)H, C(12)H, 3J = 8.8 Hz); 6.99 (d,
2 H, C(9)H, C(11)H, 3J = 8.8 Hz); 9.00 (br.s, 1 H, OH).
13C NMR, δ: 34.12 (t, C(2)); 55.29 (t, C(4), C(6)); 115.52 (d,
C(9), C(11)); 118.85 (d, C(8), C(12)); 137.53 (s, C(7));
151.19 (s, C(10)). Mass spectrum, m/z (Irel (%)): 213 [M]+
(42); 167 [M – CH2S]+ (12); 135 [M – C6H6]+ (26); 121
[M – CH2SCH2S]+ (100); 120 [M – CH2SCH2SH]+ (56); 107
[M – CH2SCH2SCH2]+ (36); 93 [CH2SCH2SH]+ (18); 46
[CH2S]+ (35), 45 [CHS]+ (41); 42 [CH2NCH2]+ (23).
C
16H18N2O2S2. Calculated (%): C, 57.83; H, 5.42; N, 8.43;
O, 9.64; S, 19.28. IR, ν/cm–1: 710, 820, 1185, 1375, 1600,
2900, 3300. UV (DMSO), λmax/nm (ε): 297.6 (10). 1H NMR
(DMSOꢀd6), δ: 3.69 (br.s, 4 H, C(5)H2, C(15)H2); 5.60
(br.s, 4 H, C(3)H2, C(13)H2); 6.30—6.88 (m, 8 H, H arom.).
13C NMR, δ: 46.38 (t, C(5), C(15)); 62.97 (t, C(3), C(13));
111.03 (d, C(10), C(20)); 126.46 (d, C(21), C(22)); 128.07 (d,
C(8), C(18)); 130.93 (d, C(9), C(19)); 148.93 (s, C(7), C(17));
155.83 (s, C(1), C(11)). Mass spectrum, m/z (Irel (%)):
279 [MH – SC2]+ (9); 167 [CH2NHC6H4OCH2S]+ (33);
149 [C6H4NHCH2SC]+ (100); 91 [OCH2SCH2NH]+ (9); 44
[CS]+ (74).
Xꢀray diffraction study of compound 9. The crystals were
obtained by crystallization from a toluene—AcOEt—acetone
(8 : 1 : 1) mixture. Experiment was carried out on a Bruker
SMART 1000 CCD Area Detector diffractometer at 120 K
(MoꢀKα radiation, 2θ
= 59.82°) for a single crystal
max
0.5×0.32×0.24 mm in size. The colorless prismatic crystals
of C9H11NOS2 (M = 213.31) are orthorhombic, at 120 K
a = 8.471(2) Å, b = 9.443(2) Å, c = 11.988(3) Å, α = 90.00°,
β = 90.00°, γ = 90.00°, V = 959.0(4) Å3, space group P212121,
Z = 4, dcalc = 1.477 g cm–3. After equivalent reflections were
averaged, 2789 independent reflections (Rint = 0.0198) were
obtained and used for structure refinement. The structure was
solved by a direct method. All atoms were located in difference
Oligomeric cyclic product 5 was prepared similarly to the
aboveꢀdescribed procedure from the starting reactants taken in
the ratio mꢀaminophenol (1.09 g, 0.01 mol) : H2S : CH2O =
1 : 1 : 2 in 95% EtOH (10 mL). M.p. 270 °C (with decomp.).
Found (%): C, 57.45; H, 5.55; N, 8.27; O, 9.59; S, 19.04.
C16H18N2O2S2. Calculated (%): C, 57.83; H, 5.42; N, 8.43;
O, 9.64; S, 19.28. IR, ν/cm–1: 710, 820, 1185, 1375, 1600, 2900,
3300. Mcr = 1333. The numerical mean value of the cycloꢀ
oligocondensation degree is ~8.
Reactions of oꢀ and pꢀaminophenols with H2S and CH2O.
A solution of oꢀaminophenol (0.33 g, 0.003 mol) or pꢀaminoꢀ
phenol (1.09 g, 0.01 mol) in 95% EtOH (10 mL) was added
dropwise for 30 min at 20 °C to a solution of formaldehyde
(37%, 0.66 mL (0.009 mol) or 2.21 mL (0.03 mol)) saturated
with hydrogen sulfide (135 mL (0.006 mol) or 448 mL (0.02 mol),
respectively). The mixture was stirred for 3 h at a specified
temperature (0, 20, 40, 80 °C), and the product was extracted
with chloroform. Mixtures of products 2 and 8 or 2 and 9 were
isolated from the organic phase after evaporation of solvents.
The reaction products prepared at 40 °C were purified by column
chromatography on SiO2 (toluene—AcOEt—acetone (8 : 1 : 1)
as eluent).
5ꢀ(2ꢀHydroxyphenyl)dihydroꢀ1,3,5ꢀdithiazine (8). The yield
was 0.55 g (86%), m.p. 102—103 °C, Rf 0.63. Found (%):
C, 50.26; H, 5.11; N, 6.11; O, 7.64; S, 30.21. C9H11NOS2.
Calculated (%): C, 50.70; H, 5.20; N, 6.60; O, 7.50; S, 30.00.
IR, ν/cm–1: 760, 1100, 1185, 1370, 1600, 2900, 3200—3500.
1H NMR (CDCl3), δ: 4.30 (br.s, 2 H, C(2)H2); 4.70 (br.s, 4 H,
C(4)H2, C(6)H2); 6.10—6.25 (m, 1 H, C(12)H); 6.79—7.21 (m,
3 H, C(9)H, C(10)H, C(11)H); 8.35 (br.s, 1 H, OH). 13C NMR,
δ: 33.79 (t, C(2)); 57.50 (t, C(4), C(6)); 115.03 (d, C(9), C(10));
119.98 (d, C(12)); 127.24 (d, C(11)); 134.73 (s, C(7));
151.01 (s, C(8)). Mass spectrum, m/z (Irel (%)): 213 [M]+ (23);
167 [M – CH2S]+ (14); 153 [M – CH2SCH2]+ (14); 121
[M – SCH2SCH2]+ (100), 107 [M – CH2SCH2SCH2]+ (46), 93
[C6H4OH]+ (59), 46 [CH2S]+ (18); 32 [S]+ (18).
electron density syntheses and refined for F 2 in the anisotroꢀ
hkl
pic approximation (hydrogen atoms were refined in the isotropic
approximation). The final R values were R1 = 0.0258 (calculated
by Fhkl for 1533 reflections with I > 2σ(I )), wR2 = 0.0610 (calꢀ
culated by F 2hkl for all 2789 reflections involved in refinement at
the last stage); GOOF = 0.996, 163 refined parameters. All
calculations were performed using the SHELXTL PLUS 5 proꢀ
gram package.18
This work was financially supported by the Council on
Grants of the President of the Russian Federation (Proꢀ
gram of State Support for Leading Scientific Schools of
the Russian Federation, Grant NSh 1060.2003.03).
References
1. S. R. Khafizova, V. R. Akhmetova, L. F. Korzhova, T. V.
Khakimova, G. R. Nadyrgulova, R. V. Kunakova, E. A.
Kruglov, and U. M. Dzhemilev, Izv. Akad. Nauk, Ser. Khim.,
2005, 423 [Russ. Chem. Bull., Int. Ed., 2005, 54, 432].
2. S. R. Khafizova, V. R. Akhmetova, R. V. Kunakova, and
U. M. Dzhemilev, Izv. Akad. Nauk, Ser Khim., 2003, 1722
[Russ. Chem. Bull., Int. Ed., 2003, 52, 1817].
3. R. V. Kunakova, S. R. Khafizova, Yu. S. Dal´nova, R. S.
Aleev, L. M. Khalilov, and U. M. Dzhemilev, Neftekhimiya,
2002, 42, 382 [Petroleum Chemistry, 2002, 42, 347 (Engl.
Transl.)].
4. S. R. Khafizova, V. R. Akhmetova, G. R. Nadyrgulova, I. V.
Rusakov, R. V. Kunakova, and U. M. Dzhemilev,
Neftekhimiya, 2005, 45, 345 [Petroleum Chemistry, 2005, 45,
374 (Engl. Transl.)].

316
Russ.Chem.Bull., Int.Ed., Vol. 55, No. 2, February, 2006
Akhmetova et al.
5. S. R. Khafizova, V. R. Akhmetova, T. V. Tyumkina, L. M.
Khalilov, R. V. Kunakova, and U. M. Dzhemilev, Izv. Akad.
Nauk, Ser. Khim., 2004, 1652 [Russ. Chem. Bull., Int. Ed.,
2004, 53, 1717].
6. E. I. Troyanskii, D. V. Demchuk, and G. I. Nikishin, Izv.
Akad. Nauk, Ser. Khim., 1997, 1256 [Russ. Chem. Bull., 1997,
46, 1199 (Engl. Transl.)].
13. Analiz nefti i nefteproduktov [Analysis of Oil and Petroleum
Products], Ed. B. M. Rybak, Gostoptekhizdat, Moscow,
1962, 5, 887 pp. (in Russian).
14. Fr. Pat. 1,341,792 (1963); Chem. Abstrs, 1964, 60, 5528d.
15. S. D. Barton and W. D. Ollis, Comprehensive Organic Chemꢀ
istry, Pergamon Press, Oxford—New York—Toronto—
Sydney—Paris—Frankfurt, 1979.
7. V. S. Chekushin and V. F. Borbat, Ekstraktsiya blagorodnykh
metallov sul´fidami i sul´foksidami [Extraction of Noble Metꢀ
als with Sulfides and Sulfoxides], Nauka, Moscow, 1984,
152 pp. (in Russian).
8. Brit. Pat. 943 273 (1963); Chem. Abstrs, 1964, 60, 5528а.
9. D. Collins and J. J. Graymore, J. Chem. Soc., 1953, 4089.
10. F. E. Poppelsdorf and S. J. Holt, J. Chem. Soc., 1954, 1124.
11. R. S. Aleev, Yu. S. Dal´nova, Yu. I. Popova, R. M.
Masagutov, and S. R. Rafikov, Dokl. Akad. Nauk SSSR,
1988, 303, 873 [Dokl. Chem., 1988 (Engl. Transl.)].
12. A. J. Gordon and R. A. Ford, The Chemist´s Companion. The
Handbook of Practical Data, Techniques and References,
J. Wiley, New York—London—Sydney—Toronto, 1972.
16. Spravochnik khimika [The Chemist´s Reference Book],
Ed. B. P. Nikol´skii, Khimiya, Moscow—Leningrad, 1964,
3, 1008 pp. (in Russian).
17. N. E. Gel´man, E. A. Terent´eva, and T. M. Shanina, Metody
kolichestvennogo organicheskogo elementnogo mikroanaliza
[Methods of Quantitative Organic Elemental Microanalysis],
Khimiya, Moscow, 1987, 296 pp. (in Russian).
18. G. M. Sheldrick, SHELXTL, Version 5, Software Reference
Manual, Siemens Industrial Automation, Madison
(WI), 1994.
Received August 5, 2005;
in revised form December 19, 2005