Reaction of sulfinic acids with heteroconjugated Alkenes

Article abstract of DOI:10.1080/10426507.2012.760562

The nucleophilic addition reactions of arenesulfinic acids with heteroconjugated alkenes have been studied. The structures of the sulfones thus obtained were confirmed by microanalytical and spectral methods. Kinetic parameters of the nucleophilic additio

Full text of DOI:10.1080/10426507.2012.760562

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Phosphorus, Sulfur, and Silicon and the
Related Elements
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Reaction of Sulfinic Acids with
Heteroconjugated Alkenes
Sonya Ivanova a
a Department of Organic Chemistry , University “Prof. Asen
Zlatarov” , Bourgas , Bulgaria
Accepted author version posted online: 25 Feb 2013.Published
online: 20 Sep 2013.
To cite this article: Sonya Ivanova (2013) Reaction of Sulfinic Acids with Heteroconjugated
Alkenes, Phosphorus, Sulfur, and Silicon and the Related Elements, 188:11, 1670-1674, DOI:
10.1080/10426507.2012.760562
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Phosphorus, Sulfur, and Silicon, 188:1670–1674, 2013
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2012.760562
REACTION OF SULFINIC ACIDS WITH
HETEROCONJUGATED ALKENES
Sonya Ivanova
Department of Organic Chemistry, University “Prof. Asen Zlatarov,”
Bourgas, Bulgaria
GRAPHICAL ABSTRACT
Abstract The nucleophilic addition reactions of arenesulfinic acids with heteroconjugated
alkenes have been studied. The structures of the sulfones thus obtained were confirmed by
microanalytical and spectral methods. Kinetic parameters of the nucleophilic addition reactions
were determined. Interactions are second-order reactions, but they are first order regarding
each reagent. The influence of various substituents at the carbon–carbon double bond on the
nucleophilic activity was studied.
Keywords Heteroconjugated alkenes; nucleophilic addition; sulfinic acids
INTRODUCTION
Heteroconjugated alkenes containing electron-withdrawing functional groups
(COCH3, CONH2, COOCH3, CN, SO2CH3, NO2, etc.) are highly reactive compounds.
Sulfinic acids act mostly as S-nucleophiles rather than O-nucleophiles because of the
presence of an electron pair at the sulfur atom.1 The addition of sulfinic acids to
α,β-unsaturated compounds is known to result in the formation of β-nitro-, keto-, cyano-,
etc. sulfones.2–8 The high reactivity of functionalized alkenes corresponds to their high
polarity and functionality; hence, they participate as reactants in similar noncatalytic
reactions. On the other hand, heteroconjugated nitroalkenes represent a special group of
Michael acceptors, which is due to the additional effect exerted by the nitro group on the
reactivity of the unsaturated system.
The present work extends this reaction to the synthesis of new polyfunctional sulfones,
and additionally, kinetic parameters of the nucleophilic addition reactions were determined.
Received 16 May 2012; accepted 15 December 2012.
Address correspondence to Sonya Ivanova, Department of Organic Chemistry, University “Prof. Asen
Zlatarov,” Bourgas, BG-8010, Bulgaria. E-mail: viperogr@abv.bg
1670

HETEROCONJUGATED ALKENES
1671
Z
Z
EtOH
R
+
SO2H
R
SO2
NO2
18°C, 10 h
NO2
3a,b,d,e,g,h
Z/R = H/OMe (a), H/NO2 (b),
1a-c
2a,b
Z = H (a), COMe (b),
d
e
R = OMe (a), NO2 (b)
COMe/OMe ( ), COMe/NO2 ( ),
c
COPh ( )
COPh/OMe (g), COPh/NO2 (h)
Z
SO2H
EtOH
+
SO2
NO2
18°C, 10 h
3c,f,i
2c
c
f
i
Z = H ( ), COMe ( ), COPh ( )
Scheme 1
Moreover, the kinetic studies allow an evaluation of the activity of the carbon–carbon double
bond in the conjugated alkenes.
RESULTS AND DISCUSSION
The interaction of arenesulfinic acids 2a–c with α,β-unsaturated compounds 1a–c
occurs according to the reactions depicted in Scheme 1.
Sulfones 3 are synthesized as results of the interaction of equimolar amounts of
the corresponding reagents in ethanol at room temperature for 10 h. IR-spectra of the
compounds studied display strong absorption bands, characteristic for both the NO2 and
SO2 functional groups. Moreover, a trend toward an increase of the frequencies of the
symmetric stretches for the NO2 group was observed. No significant changes in this respect
were found for the SO2 group. The high intensities of these characteristic bands should be
expected, having in mind the geometry of the SO2 group with its out-of-plane location with
respect to the other substituent. The IR-spectra of these particular organosulfur compounds
show clearly that the SO2 group cannot be considered as analogous to the carbonyl group,
due to the differences in the symmetry and the electron structure. The spectral studies
did not reveal any existence of conjugation between the SO2 and NO2 groups, which
should be expected from their location at different planes. The absorption bands for the
carbonyl groups were observed at 1705–1695 cm−1. Medium-intensity absorption band
at 1090–1080 cm−1 was also observed, which could be assigned to the stretching S-aryl
vibration. The band at 855–845 cm−1 could be assigned to stretching C N vibration.
Deformation C H vibrations, corresponding to three neighboring hydrogen atoms in the
β-SO2C10H7 group, were observed at 810–785 cm−1
.
Skeletal vibrations of the benzene ring were characterized by the bands at
1640–1450 cm−1, and out-of-plane C H aryl vibration within 725–720 and 830–790 cm−1
proved the presence of monosubstituted and disubstituted benzene ring, respectively. The

1672
S. IVANOVA
presence of the p-methoxy group in the benzene ring was proved by the characteristic
stretching vibration of the CH3-group in methyl phenyl esters at 2845 cm−1, and also by
the bands at 1275 and 1025 cm−1, corresponding to C O C fragment.
1
In the H NMR spectra, multiplets characteristic for the aromatic protons are ob-
served in the region of 7.00–7.80 ppm. The corresponding 13C NMR signals appear at
128–135 ppm. In the case of 3a–c, the protons of the ethane unit appear as doublet at
5.14–5.18 ppm and triplet at 6.18–6.21 ppm with a coupling constant of about 14 Hz. The
corresponding 13C NMR signals are found at 25–30 ppm and at 38–45 ppm, respectively.
The NMR data also show that the sulfones are formed as a mixture of two stereoisomers.
The main kinetic parameters of the nucleophilic addition of sulfinic acids 2a,b to
nitroalkenes 1a–c were determined by HPLC. This method was suggested by Aleksiev and
Ivanova.9 and modified by us to determine the kinetic parameters of the reaction. In all
cases, the reactions were second order, but they were first order regarding the substrate and
the nucleophilic reagent. The calculations were made by differential and integral methods in
a wide concentration range 0.05–10 M. The results obtained were worked out by regression
analysis with a correlation coefficient greater than 0.98. These results are very close to linear
dependences and satisfy a second-order kinetic equation. The exact experimental values of
the reaction order for the interaction between 1a and 2a (2b) were 1.69 (1.74) determined
by Van’t Hoff’s method, and 1.79 (1.72) calculated by half-time method. The second-order
rate constants for the addition of 2a to 1a at 288, 398, 308 K are 12.75 ( 0.1) × 10−4 M−1
s
−1, 16.60 ( 0.1) × 10−4 M−1
s
−1, 19.05 ( 0.1) × 10−4 M−1
s
−1, respectively. The rate
constants of the reaction of 1a with 2b are 2.75 ( 0.1) × 10−4 M−1 s−1, 4.60 ( 0.1) × 10−4
M
−1 s−1, 7.65 ( 0.1) × 10−4 M−1 s−1 (T = 288, 398, 308 K), respectively. The activation
energy and the enthalpy of activation of the reaction of 1a and 2a were calculated to 47.26
and 45.50 kJ mol−1, respectively. These results confirm the trend of the already observed
nucleophilic activity of sulfinic acids depending on the substituent in the benzene ring. The
activity of the nitroethylene system increases in the presence of COMe (COPh) group in
α-position to NO2: rate constants are 10.09 ( 0.1) × 10−4 M−1 s−1, 25.50 ( 0.1) × 10−4
M
−1 s−1, 49.70 ( 0.1) × 10−4 M−1 s−1 (T = 288, 398, 308 K) for nucleophilic addition of
2a to 1b and 5.15 ( 0.1) × 10−4 M−1 s−1, 16.30 ( 0.1) × 10−4 M−1 s−1, 42.70 ( 0.1) ×
10−4 M−1 s−1 for the interaction between 1c and 2a.
CONCLUSIONS
1. A new series of nitro- and ketosulfones was synthesized by the nucleophilic addition of
sulfinic acids to heteroconjugated alkenes.
2. The reactivity of nitrochalcones correlates with that of nitroethenyl arenes in nucleophilic
addition reactions.
3. The nucleophilic activity of sulfinic acids increases with the introduction of electron-
donatingsubstituents and decreases in thepresence of electron-withdrawingsubstituents.
EXPERIMENTAL
Methods
Melting points are uncorrected. IR spectra (KBr) were recorded with a Bruker spec-
trophotometer. 1H and 13C NMR spectra were recorded with a Bruker (350 MHz) spectrom-
eter using CDCl3 as solvent and TMS as internal standard. Chemical shifts are reported as δ

HETEROCONJUGATED ALKENES
1673
values. Microanalytical data were obtained using an elemental Analizer-1104 (Carlo–Erba).
Selected physical and spectroscopic characteristics for synthesized compounds are given be-
low. HPLC was performed using a Series-4 apparatus (Perkin–Elmer) and a programmable
multiwavelength detector.
Synthesis of Compounds 3a–i: General Procedure
To the nitroalkene (0.1 mol) in 95% ethanol was added the corresponding sulfinic
acid (0.1 mol). The reaction mixture was kept standing at 18 ◦C for 10 h. The crystalline
products obtained were filtered and purified by recrystallization from dioxane/toluene. The
products were found to be stable on prolonged storage in air and were soluble in acetone
and chloroform but resulted insoluble in water, n-hexane and petroleum ether. The yields
obtained varied within the range 93%–98%.
3a: Yield 93%; colorless crystals; mp 166 ◦C; IR (KBr, cm−1) υ: 1550, 1360 (NO2),
1305, 1140 (SO2); 1H NMR (CDCl3) δ: 7.20–7.75 (m, 9H, arom-H), 5.15 (d, JHH = 14.2 Hz,
1H, CH), 6.20 (t, JHH = 14.2 Hz, 2H, CH2); 13C NMR (CDCl3) δ: 26.2, 28.2 (CH2), 41.3
(CH), 129.6–147.3 (Ar-C). Calcd for C15H15NO5S (321.23): C, 56.07; H, 4.67; N, 4.36, S,
9.98%. Found: C, 56.00; H, 4.66; N, 4.34; S, 9.96%.
3b: Yield 96%; colorless crystals; mp 159 ◦C; IR (KBr, cm−1) υ: 1555, 1360, (NO2),
1360, 1140 (SO2); 1H NMR (CDCl3) δ: 7.22–7.78 (m, 9H, arom-H), 5.16 (d, JHH = 14.2 Hz,
1H, CH), 6.19 (t, JHH = 14.2 Hz, 2H, CH2); 13C NMR (CDCl3) δ: 26.7, 29.1 (CH2), 40.3
(CH), 128.6–150.7 (C-Ar). Calcd for C14H12N2O6S (336.32): C, 50.00; H, 3.57; N, 8.37;
S, 9.53%. Found: C, 49.93; H, 3.56; N, 8.37; S, 9.52%.
3c: Yield 95%; colorless crystals; mp 188 ◦C; IR (KBr, cm−1) υ: 1560, 1365 (NO2),
1
1310, 1140 (SO2); H NMR (CDCl3) δ: 7.22–7.83 (m, 12H, arom-H), 5.15 (d, JHH
=
13.9 Hz, 1H, CH), 6.19 (t, JHH = 13.9 Hz, 2H, CH2); 13C NMR (CDCl3) δ: 25.2, 28.2
(CH2), 40.4 (CH), 132.2–155.6 (C-Ar). Calcd for C18H15NO4S (405.29): C, 53.34, H, 3.71,
N, 3.46, S, 7.91%. Found: C, 53.32; H, 3.69; N, 3.45; S, 7.90%.
3d: Yield 95%; colorless crystals; mp 156 ◦C; IR (KBr, cm−1) υ: 1560, 1360 (NO2),
1310, 1135 (SO2), 1695 (CO); 1H-NMR (CDCl3) δ: 7.09–7.88 (m, 9H, arom-H), 5.12 (d,
JHH = 14.1 Hz, 1H, CH), 6.21 (d, JHH = 14.1 Hz, 1H, CH); 13C NMR (CDCl3) δ: 24.8,
26.2 (CH2), 39.1 (CH), 129.3–153.8 (C-Ar). Calcd for C17H17NO6S (363.25): C, 56.21; H,
4.68; N, 3.86; S, 8.83%. Found: C, 56.20; H, 4.65; N, 3.85; S, 8.82%.
3e: Yield 95%; colorless crystals; mp 155 ◦C; IR (KBr, cm−1) υ: 1560, 1360 (NO2),
1310, 1140 (SO2), 1695 (CO); 1H NMR (CDCl3) δ: 7.20–7.72 (m, 9H, arom-H), 5.16 (d,
JHH = 14.1 Hz, 1H, CH), 6.20 (d, JHH = 14.1 Hz, 1H, CH); 13C NMR (CDCl3) δ: 24.7,
27.5 (CH2), 40.3 (CH), 128.2–158.9 (C-Ar). Calcd for C16H14N2O7S (378.25): C, 50.81;
H, 3.70; N, 7.41; S, 8.48%. Found: C, 50.80; H, 3.68; N, 7.40; S, 8.46%.
3f: Yield 97%; colorless crystals; mp 184 ◦C; IR (KBr, cm−1) υ: 1560, 1355 (NO2),
1310, 1140 (SO2), 1695 (CO); 1H NMR (CDCl3) δ: 7.23–7.80 (m, 12H, arom-H), 5.15 (d,
JHH = 14.0 Hz, 1H, CH), 6.20 (d, JHH = 14.0 Hz, 1H, CH); 13C NMR (CDCl3) δ: 25.4,
27.8 (CH2), 40.3 (CH), 131.2–159.3 (C-Ar). Calcd for C20H17NO5S (383.24): C, 62.68; H,
5.11; N, 3.65; S, 8.37%. Found: C, 62.66; H, 5.09; N, 3.62; S, 8.35%.
3g: Yield 96%; colorless crystals; mp 176 ◦C; IR (KBr, cm−1) υ: 1560, 1355 (NO2),
1310, 1140 (SO2), 1705 (CO); 1H NMR (CDCl3) δ: 7.24–7.70 (m, 14H, arom-H), 5.15 (d,
JHH = 14.1 Hz, 1H, CH), 6.19 (d, JHH = 14.1 Hz, 1H, CH); 13C NMR (CDCl3) δ: 23.8,
25.9 (CH2), 40.4 (CH), 130.2–152.8 (C-Ar). Calcd for C22H19NO6S (425.31): C, 62.13; H,
4.47; N, 3.29; S, 7.54%. Found: C, 62.11; H, 4.46; N, 3.27; S, 7.52%.

1674
S. IVANOVA
3h: Yield 98%; colorless crystals; mp 182 ◦C; IR (KBr, cm−1) υ: 1560, 1360 (NO2),
1310, 1140 (SO2), 1705 (CO); 1H NMR (CDCl3) δ: 7.25–7.72 (m, 14H, arom-H), 5.16 (d,
JHH = 14.0 Hz, 1H, CH), 6.20 (d, JHH = 14.0 Hz, 1H, CH); 13C NMR (CDCl3) δ: 24.4,
26.7 (CH2), 39.3 (CH), 129.4–156.6 (C-Ar). Calcd for C21H16N2O7S (440.30): C, 57.29;
H, 3.63; N, 6.39; S, 7.28%. Found: C, 57.28; H, 3.60; N, 6.37; S, 7.27%.
3i: Yield 98%; colorless crystals; mp 187 ◦C; IR (KBr, cm−1) υ: 1560, 1355 (NO2),
1310, 1140 (SO2), 1705 (CO); 1H NMR (CDCl3) δ: 7.20–7.78 (m, 17H, arom-H), 5.16 (d,
JHH = 14.0 Hz, 1H, CH), 6.20 (d, JHH = 14.0 Hz, 1H, CH); 13C NMR (CDCl3) δ: 22.8,
25,1 (CH2), 40.2 (CH), 130.2–157.6 (C-Ar). Calcd for C25H19NO5S (445.34): C, 67.98; H,
4.27; N, 3.14; S, 7.20%. Found: C, 67.96; H, 3.12; N, 3.12: S, 7.20%.
Rate Measurement
The purified sulfinic acid (0.001 mol) was added to the corresponding nitroalkene
(0.001 mol) in ethanol (50 mL). Aliquots were taken out at regular intervals of time and
diluted with ethanol. Flow concentration of nitroalkene during the reaction was determined
by liquid chromatographic analysis. The experimental data obtained were consistent with a
second-order kinetic equation yielding linear regression analysis with correlation coefficient
0.95, which proved the relevancy of the linear approximation.
The second-order constants, the activation energy, and enthalpy of activation were
calculated according to known procedure.10
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1. Drabowicz, J.; Kielbasinski, P.; Mikolajczyk, M. In: S. Patai (Ed.), The Chemistry of Sulfinic
acids, Esters ad Derivatives; Wiley: New York, 1990, Ch. 12, pp. 370-374.
2. Feldman, I. K.; Mikhailova, V. N. Zh. Obshch. Khim. 1962, 32, 944-946; ibid. 1963, 33, 2111-
2113.
3. Mikhailova, V. N.; Borisova, N.; Stankevich, D. Russ. J. Org. Chem. 1966, 2, 1437-1439.
4. Wuld, F.; Lightner, D. C. J. Am. Chem. Soc. 1967, 89, 4099-4104.
5. Pinnick, H.; Reynolds, M. J. Org. Chem. 1979, 44, 160-168.
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8. Oae, C. In: E. N. Prilejaeva (Ed.), The Chemistry of Organic Sulfur Compounds; Khimiya:
Moscow, 1975, Ch. 9, pp. 398-431 (Russ.).
9. Aleksiev, D. I.; Ivanova, S. Phosphorus, Sulfur Silicon Relat. Elem. 1993, 85, 73-75 ibid. 2006,
181, 1601-1607.
10. Schmid, R.; Sapunov, N. V. Non-Formal Kinetics; Verlag Chemie: Weinheim, 1982, 148, pp.
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