Selective introduction of sulfo groups into aromatic nitro compounds

Article abstract of DOI:10.1016/j.mencom.2007.11.017

A new reaction has been found, viz. oxidative destruction of nitro-substituted sulfones ArSO₂CH₂CO₂Me to give sulfonic acids ArSO₃H on treatment with 70% HNO₃; in addition, di(arylsulfonyl)furoxans ar

Full text of DOI:10.1016/j.mencom.2007.11.017

Mendeleev
Communications
Mendeleev Commun., 2007, 17, 347–348
Selective introduction of sulfo groups
into aromatic nitro compounds
Mikhail D. Dutov,a Olga V. Serushkina,a Svyatoslav A. Shevelev*a and Konstantin A. Lyssenkob
a N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russian
Federation. Fax: +7 499 135 5328; e-mail: shevelev@ioc.ac.ru
b A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 119991 Moscow,
Russian Federation
DOI: 10.1016/j.mencom.2007.11.017
A new reaction has been found, viz. oxidative destruction of nitro-substituted sulfones ArSO2CH2CO2Me to give sulfonic acids
ArSO3H on treatment with 70% HNO3; in addition, di(arylsulfonyl)furoxans are formed as by-products.
The direct sulfonation of aromatic nitro compounds involves
considerable difficulties where the benzene ring has two or
more nitro groups as substituents or where sulfonation to a
position deactivated by a nitro group (e.g., a para position) is
required.
We have found a method for the selective introduction of
sulfo groups into aromatic nitro compounds, where nucleophilic
substitution activated by a nitro group is used at the first stage
instead of hindered electrophilic substitution.
ArO2S
SO2Ar
70% HNO3,
NaNO2
ArSO2CH2CO2Me
ArSO3H + N
N
reflux
O
O
3a–c
4
5a 10%
5b 5%
5c 21%
KOH
ArSO3K
K-4a 80%
K-4b 66%
K-4c 55%
Scheme 2
K2CO3
– X–
ArX + HSCH2CO2Me
ArSCH2CO2Me
The structure of arenesulfonic acids 4 was determined based
on H NMR data and elementary analyses of their potassium
salts (K-4). In the case of furoxans 5, the structure of compound
5a was determined by X-ray diffraction analysis, while those of
compounds 5b,c were determined similarly to compound 5a as
well as using 1H NMR data and elementary analyses.
1a–c
2
1
H2O2
ArSO2CH2CO2Me
AcOH
3
NO2
Me
F
O2N
NO2
According to X-ray diffraction data obtained from a crystal of
compound 5a,§ though the molecule has the C1 point group, it
occupies a special position, viz., the C2 axis passing through the
middle of the C(1)–C(1A) bond; this leads to statistic disorder
of the O(1) and O(2) atoms. Note that this disorder is not sym-
metry-imposed and persists also in noncentrosymmetric ortho-
rhombic as well as in monoclinic space groups (treated as
merohedral twins). In the crystal, the phenyl ring is almost
O2N
NO2
NO2
NO2
1a
1b
1c
Scheme 1
The nucleofuge (NO2, Hal) located at the benzene-ring
position to which an SO3H group needs to be introduced in the
molecule of nitro compound 1 is replaced on treatment with an
ester of thioglycolic acid in the presence of K2CO3 (in N-MP or
DMF) to give S-arylthioglycol ester 2. Corresponding sulfones
3 were obtained by the oxidation of sulfides 2 with aqueous
H2O2 in acetic acid. The following examples are provided:
1,3,5-trinitrobenzene (1a, one NO2 group is replaced), 2,4,6-tri-
nitrotoluene (1b, only ortho-NO2 is replaced) and p-fluoro-
nitrobenzene (1c, the fluorine atom is replaced) (Scheme 1).†
We have found a new reaction (Scheme 2): the heating of
sulfones 3 with 70% HNO3 in the presence of a catalytic
amount of NaNO2 results in the oxidative destruction of sulfones
3 to give corresponding nitro-substituted arenesulfonic acids 4
isolated as stable potassium salts (K-4). The corresponding di(aryl-
sulfonyl)furoxans 5 are also formed as by-products (Scheme 2).‡
Although Farrar5 obtained di(arylsulfonyl)furoxans as main
products of the treatment of arylsulfonylacetic acids with a
mixture of HNO3 and AcOH, they were formed in minor
amounts in our case with the predominant formation of
arylsulfo acids.
†
Previously, we have already described the synthesis of sulfide 2b and
sulfone 3b from 2,4,6-trinitrotoluene 1b.1 Sulfides 2a,c and sulfones
3a,c were obtained similarly from nitro compounds 1a,c, respectively.
1H NMR spectra were recorded with a Bruker AM-300 instrument.
The chemical shifts in [2H6]DMSO are reported relative to TMS. The
melting points of the resulting compounds were determined on a Boetius
hot stage according to Koffler (the heating rate was 4 K min–1).
1
For 2a: yield 78%; mp 93–95 °C (from EtOH). H NMR, d: 8.60 (t,
1H, 4J 1.9 Hz), 8.49 (d, 2H, 4J 1.9 Hz), 4.30 (s, 2H), 3.69 (s, 3H). Found
(%): C, 39.48; H, 2.79; N, 9.96; S, 11.49. Calc. for C9H8N2O6S (%): C,
39.71; H, 2.96; N, 10.29; S, 11.78.
For 2c: yield 85%; mp 51–52 °C (from MeOH) (lit.,2 mp 50.9–52.4 °C).
3
3
1H NMR, d: 8.15 (d, 2H, J 5.8 Hz), 7.52 (d, 2H, J 5.8 Hz), 4.15 (s,
2H), 3.66 (s, 3H).
For 3a: yield 72%; mp 81–83 °C (from AcOH–H2O, 3:2). 1H NMR, d:
4
9.15 (t, 1H, J 2.1 Hz), 9.03 (d, 2H, 4J 2.1 Hz), 5.12 (s, 2H), 3.62 (s,
3H). Found (%): C, 35.75; H, 2.69; N, 8.93; S, 10.45. Calc. for C9H8N2O8S
(%): C, 35.53; H, 2.65; N, 9.21; S, 10.54.
For 3c: yield 86%; mp 127–129 °C (from MeOH) (lit.,2 mp 128.7–130 °C).
3
3
1H NMR, d: 8.47 (d, 2H, J 6.0 Hz), 8.20 (d, 2H, J 6.0 Hz), 4.90 (s,
2H), 3.62 (s, 3H).
– 347 –
© 2007 Mendeleev Communications. All rights reserved.

Mendeleev Commun., 2007, 17, 347–348
HNO3
O(1)
O(2)
N(1)
ArSO2CH2CO2Me
ArSO2CCO2Me
(HNO2, N2O4)
O(7)
O(7A)
3
N(1A)
C(1A)
NOH
N(3)
C(7)
C(6)
N(3A)
C(7A)
6
C(1)
O(8A)
O(4)
C(2)
O(4A)
O(8)
H+, H2O
ArSO2CCO2H
NOH
HNO3
C(6A)
C(5A)
b
C(2A)
S(1A)
O(3) O(3A)
S(1)
C(3)
a
C(5)
C(4A)
C(4)
C(3A)
ArSO2CCO2Me
N(2A)
N(2)
ArSO2C–NO2
NOH
O
O(6A)
O(6)
O(5A)
O(5)
H2O – HOCOCO2Me
∆
– HNO2
Figure 1 General view of 5a molecule. The statistic disorder is omitted
for clarity.
ArSO2H
HNO3
ArSO2C
N
O
‡
General procedure for the synthesis of potassium sulfonates. Sulfone
3a–c (1 g) was dissolved in 5 ml of 70% nitric acid and two or three
crystals of NaNO2 were added. The mixture was slowly heated with
stirring; nitrogen oxides were evolved. The mixture was refluxed for 3 h.
In the case of sulfones 3a and 3c, white precipitates were formed from
the reaction mixture (furoxans 5a or 5c). After refluxing, the reaction
mixture was quickly cooled. Furoxans 5a,c were filtered off, washed
with water and dried in air. Furoxan 5b was obtained by pouring the
reaction mixture into cold water. The white precipitate was filtered off
and dried. The filtrates obtained after the separation of the furoxans were
evaporated to dryness in vacuo. The residue was dissolved in EtOH, and
a solution of an equimolar amount (with respect to compound 3) of KOH
in ethanol was added with stirring and cooling. The resulting precipitate
of the potassium salt of sulfonic acid 4a–c was filtered off and dried in air.
For K-4a:3 yield 80%; mp 332–334 °C (from water). 1H NMR, d: 8.79
(t, 1H, 4J 1.9 Hz), 8.63 (d, 2H, 4J 1.9 Hz). Found (%, K as K2SO4 ash):
C, 25.27; H, 1.08; N, 9.36; S, 10.92; K, 13.73. Calc. for C6H3KN2O7S
(%): C, 25.17; H, 1.06; N, 9.79; S, 11.20; K, 13.66.
4
5
Scheme 3
perpendicular to the furoxan ring, the dihedral angle being
77.8°. Such a mutual disposition of the rings results in the
presence of a rather short intramolecular contact O(2)···O(4)
[2.817(5) Å], which can lead to the observed disorder in the
crystal. The nitro groups in compound 5a are almost coplanar
to the aryl ring, with the torsion angles O(5)N(2)C(4)C(3) and
O(7)N(3)C(6)C(7) equal to 17°.
Analysis of the intermolecular contacts has revealed the
presence of a rather rare SO2···O2N type of contact [O(5)···O(3)
equal to 2.963(2) Å], as well as NO2···π contact with the
O(6)···C(3) distance equal to 3.178 Å.
The chemistry of the process requires an additional study;
however, considering the fact that the oxidative destruction is
initiated by NaNO2 and nitrogen oxides are liberated during
the reaction, it can be assumed that the primary step involves
the nitrozation of the reactive methylene unit in sulfones 3 to
give corresponding oximes 6 (Scheme 3). A possible variant
that explains the formation of both arenesulfonic acids 4 and
furoxans 5 is shown in Scheme 3.
Thus, the three examples above show the possibility of the
selective introduction of sulfonic groups into the molecules of
aromatic nitro compounds by means of nucleophilic replacement
of a nitro group or a halogen substituent on treatment with an
ester of thioglycolic acid, followed by oxidation of the resulting
S-arylthioglycolic ester to the corresponding sulfone and oxidative
destruction of the latter to give a nitro-substituted arenesulfonic
acid. It should be noted that the use of nucleophilic substitution
for introducing a sulfo group into an aromatic ring was known
before.6,7 However, this method is unsuitable for replacing a
relatively weakly activated nucleofuge, as shown for trinitro
derivatives 1a,b with meta-arranged nitro groups: the nitro group in
these compounds is not replaced even in dipolar aprotic solvents.
1
For K-4b: yield 66%; mp 360 °C (from EtOH). H NMR, d: 8.78 (d,
1H, 4J 2.1 Hz), 8.63 (d, 1H, 4J 2.1 Hz), 8.63 (d, 1H, 4J 2.1 Hz), 2.71 (s,
3H). Found (%): C, 28.35; H, 1.70; N, 9.36; S, 10.20; K, 13.45. Calc. for
C7H5KN2O7S (%): C, 28.00; H, 1.68; N, 9.33; S, 10.68; K, 13.02.
For K-4c: yield 55%; mp 360 °C (from EtOH) (lit.,4 mp 328 °C).
1H NMR, d: 8.21 (d, 2H, 3J 6.1 Hz), 7.86 (d, 2H, 3J 6.1 Hz). Found (%):
C, 30.08; H, 1.71; N, 5.64; S, 13.31; K, 16.38. Calc. for C6H4KNO5S
(%): C, 29.87; H, 1.67; N, 5.81; S, 13.29; K, 16.21.
For 5a: yield 0.092 g (10%); mp 250–252 °C. 1H NMR, d: 9.29 (t, 1H,
4J 2.0 Hz), 9.19 (t, 1H, 4J 2.0 Hz), 9.10 (d, 2H, 4J 1.9 Hz), 8.88 (d, 2H,
4J 1.9 Hz). Found (%): C, 30.81; H, 1.11; N, 15.33; S, 11.61. Calc. for
C14H6N6O14S2 (%): C, 30.78; H, 1.11; N, 15.38; S, 11.74.
For 5b: yield 0.035 g (5%); mp 213–215 °C (from 1,2-dichloroethane).
1H NMR, d: 9.28 (d, 1H, 4J 2.0 Hz), 9.21 (d, 1H, 4J 2.0 Hz), 9.12 (d, 1H,
4
4J 2.0 Hz), 9.02 (d, 1H, J 2.0 Hz), 2.75 (s, 3H), 2.65 (s, 3H). Found
(%): C, 33.70; H, 1.79; N, 14.39; S, 11.49. Calc. for C16H10N6O14S2 (%):
C, 33.46; H, 1.75; N, 14.63; S, 11.16.
1
For 5c: yield 0.184 g (21%); mp 239–241 °C. H NMR, d: 8.62 (m,
4H), 8.38 (d, 2H, 3J 5.9 Hz), 8.22 (d, 2H, 3J 5.9 Hz). Found (%): C,
38.57; H, 1.72; N, 12.30; S, 13.95. Calc. for C14H8N4O10S2 (%): C, 38.85;
H, 1.77; N, 12.28; S, 14.05.
§
The crystals of compound 5a (M = 264.24) are orthorhombic, space
group Pbcn, at 100 K: a = 27.548(3), b = 12.0893(8), c = 12.3106(9) Å,
V = 2481.5(3) Å3, Z = 4 (Z' = 0.5), dcalc = 1.845 g cm–3, (MoKα) = 3.66 cm–1,
F(000) = 1104. The intensities of 9194 reflections were measured with a
Bruker SMART APEX2 CCD diffractometer [l(MoKα) = 0.71072 Å,
w-scans, 2q < 58°] and 2167 independent reflections [Rint = 0.0643]
were used in further refinement. The structure was solved by the direct
method and refined by the full-matrix least-squares technique against F2
in the anisotropic–isotropic approximation. Analysis of the Fourier synthesis
revealed that the O(1) and O(2) atoms are disordered over two positions
around two fold axis. The positions of hydrogen atoms were calculated
geometrically. For compound 5a, the refinement converged to wR2 =
= 0.0757 and GOF = 0.987 for all independent reflections [R1 = 0.0389
was calculated against F for 1349 observed reflections with I > 2s(I)].
All calculations were performed using SHELXTL PLUS 5.0.
This study was supported in part by ISTC (project no. 3197)
and the Russian Foundation for Basic Research (OFI-a grant
no. 05-03-08164).
References
1 O. V. Serushkina, M. D. Dutov and S. A. Shevelev, Izv. Akad. Nauk, Ser.
Khim., 2001, 252 (Russ. Chem. Bull., Int. Ed., 2001, 50, 261).
2 R. F. Langler and J. L. Steeves, Aust. J. Chem., 1994, 47, 1641.
3 R. H. Griffith, J. Chem. Soc., 1924, 125, 1401.
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CCDC 666455 contains the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
For details, see ‘Notice to Authors’, Mendeleev Commun., Issue 1, 2007.
Received: 23rd May 2007; Com. 07/2944
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