Selective oxidation of sulfides to sulfoxides and sulfones using n-butyltriphenylphosphonium dichromate (BunPPh3) 2Cr2O7 in the presence of aluminium chloride in solution and under microwave irradiation

Article abstract of DOI:10.1080/104265090968091

A wide variety of sulfides are efficiently oxidized to their corresponding sulfoxides and sulfones in excellent yields using n-butyltriphenylphosphonium dichromate (BTPPDC) in the presence of aluminium chloride in acetonitrile solution and under microwave irradiation. In addition, selective oxidation of sulfides in the presence of functional groups such as a carbon-carbon double bond, ketone, oxime, aldehyde, ether, and acetal can be considered as a noteworthy advantage of this method. Copyright Taylor & Francis Inc.

Full text of DOI:10.1080/104265090968091

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Phosphorus, Sulfur, and Silicon
and the Related Elements
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Selective Oxidation of
Sulfides to Sulfoxides
and Sulfones Using n -
Butyltriphenylphosphonium
Dichromate (Bu n PPh3)2Cr2O7
in the Presence of Aluminium
Chloride in Solution and Under
Microwave Irradiation
Iraj Mohammadpoor-Baltork a , Hamid Reza
Memarian a , Kiumars Bahrami a & Karim Esmayilpour
a
a Department of Chemistry , Isfahan University ,
Isfahan, Iran
Published online: 19 Aug 2006.
To cite this article: Iraj Mohammadpoor-Baltork , Hamid Reza Memarian , Kiumars
Bahrami & Karim Esmayilpour (2005) Selective Oxidation of Sulfides to Sulfoxides
and Sulfones Using n -Butyltriphenylphosphonium Dichromate (Bu n PPh3)2Cr2O7 in
the Presence of Aluminium Chloride in Solution and Under Microwave Irradiation,
Phosphorus, Sulfur, and Silicon and the Related Elements, 180:12, 2751-2766, DOI:
10.1080/104265090968091
To link to this article: http://dx.doi.org/10.1080/104265090968091
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Phosphorus, Sulfur, and Silicon, 180:2751–2766, 2005
Copyright © Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/104265090968091
Selective Oxidation of Sulfides to Sulfoxides
and Sulfones Using n-Butyltriphenylphosphonium
Dichromate (BunPPh3)2Cr2O7 in the Presence
of Aluminium Chloride in Solution and Under
Microwave Irradiation
Iraj Mohammadpoor-Baltork
Hamid Reza Memarian
Kiumars Bahrami
Karim Esmayilpour
Department of Chemistry, Isfahan University, Isfahan, Iran
A wide variety of sulfides are efficiently oxidized to their corresponding sulfoxides
and sulfones in excellent yields using n-butyltriphenylphosphonium dichromate
(BTPPDC) in the presence of aluminium chloride in acetonitrile solution and under
microwave irradiation. In addition, selective oxidation of sulfides in the presence of
functional groups such as a carbon–carbon double bond, ketone, oxime, aldehyde,
ether, and acetal can be considered as a noteworthy advantage of this method.
Keywords Dichromate; oxidation; sulfides; sulfones; sulfoxides
INTRODUCTION
The selective oxidation of sulfides to sulfoxides or sulfones is an impor-
tant synthetic transformation. These compounds are used as important
intermediates in organic synthesis.1 The most widely used method for
the preparation of sulfoxides and sulfones is the oxidation of the corre-
sponding sulfides. A number of methods have been reported for these
transformations in the literature.2−29 However, some of these methods
show limitations such as long reaction times, low yields of the products,
expensive reagents, and poor selectivity. On the other hand, selective
oxidation of sulfides to sulfoxides and sulfides to sulfones using the
same reagent system under adjusted reaction conditions is of practical
Received April 1, 2004; accepted August 3, 2005.
We are thankful to the Isfahan University Research Council for their partial support
of this work.
Address correspondence to Iraj Mohammadpoor-Baltork, Isfahan University, Depart-
ment of Chemistry, Isfahan 81746-73441, Iran. E-mail: imbaltork@sci.ui.ac.ir
2751

2752
I. Mohammadpoor-Baltork et al.
importance and only a few reports are available in the literature for this
purpose.30 Therefore, there is still a need for a simple and less expensive
method for the conversion of sulfides to sulfoxides and sulfones.
In recent years organic reactions assisted by microwave irradiation
have gained special attention.31 The chief features of the microwave
reactions are the much-improved reaction rates, formation of cleaner
products, and operational simplicity.
RESULTS AND DISCUSSION
In this article, we describe
a
successful application of n-
butyltriphenylphosphonium dichromate/AlCl3 system for the selective
oxidation of sulfides to sulfoxides and sulfides to sulfones according to
the appropriate adjustment of the reaction conditions in solution and
under microwave irradiation (Scheme 1).
SCHEME 1
BTPPDC is an inexpensive reagent and easily is prepared from the
commercially available starting materials. Oxidation of different or-
ganic compounds using this reagent previously has been reported.32
At first, the oxidation of 4-bromobenzyl phenyl sulfide (1e) as a model
compound was examined with BTPPDC in refluxing acetonitrile. Under
this condition, the reaction did not proceed at all after 2 h and the start-
ing material was isolated intact from the reaction mixture. In recent
years the effect of Lewis acids as a promoter or catalyst for the oxida-
tion of organic substrates has been reported.33 Therefore, the effect of
several Lewis acids upon the reactivity of BTPPDC for the oxidation of
4-bromobenzyl phenyl sulfide in refluxing acetonitrile has been studied.
The results show that only AlCl3 is effective for this purpose (Table I).
The oxidation of 4-bromobenzyl phenyl sulfide to the corresponding
sulfoxide also was investigated with BTPPDC/AlCl3 in various solvents.
Among the solvents that were examined, acetonitrile turned out to be
a suitable solvent for this transformation (Table II).

Oxidation of Sulfides to Sulfoxides and Sulfones
2753
O
||
BTPPDC/Lewis acid
TABLE I 4-BrC6H4CH2SC6H5 −−−−−−−−−−−−→ 4-BrC6H4CH2SC6H5
CH CN, reflux
3
Entry
Lewis acida
Time (min)
Yield (%)b
1
2
3
4
5
6
AlCl3
BiCl3
SnCl2.2H2O
NiCl2.6H2O
FeCl3.6H2O
CoCl2.6H2O
70
70
70
70
70
70
94
76
75
60
70
70
aSulfide: BTPPDC: Lewis acid = 1:1.5:1.
bIsolated yields.
The optimum molar ratio of sulfide to BTPPDC to AlCl3 (1:1.5:1) is
found to be ideal for the complete conversion of sulfides to sulfoxides
in solution and 1:1.2:1 under microwave irradiation, while with lesser
amounts (for example, 1:1:0.75 and 1:1:1) the reaction remains incom-
plete. As shown in Table III, a series of diaryl, dibenzyl, aryl benzyl,
dialkyl, and cyclic sulfides 1a–s were then reacted with this reagent
system in refluxing acetonitrile, which afforded the corresponding sul-
foxides 2a–s in 85–95% yields within 40–240 min. The oxidation of
these sulfides to sulfoxides also was investigated under microwave ir-
radiation. Under these conditions, the corresponding sulfoxides were
obtained in 85–96% yields and in a very short reaction time (0.75–
5.5 min), (Table III). However, in oxidation of alkyl aryl sulfides such
as methyl phenyl sulfide and 4-chlorophenyl methyl sulfide, a mixture
of sulfoxide (∼65%) and sulfone (∼30%) was isolated from the reaction
mixture.
In order to extend the scope of this reagent system further, the oxida-
tion of sulfides to their corresponding sulfones also was investigated in
O
||
BTPPDC/Alcl
3
TABLE II 4-BrC6H4CH2SC6H5 −−−−−−−→ 4-BrC6H4CH2SC6H5
Solvent, reflux
Entry
Solventa
Time (min)
Yield (%)b
1
2
3
4
5
CH3CN
CH3COCH3
CHCl3
CH2Cl2
n-Hexane
70
70
70
70
70
94
81
60
50
10
aSulfide: BTPPDC: AlCl3 = 1:1.5:1.
bIsolated yields.

2754
I. Mohammadpoor-Baltork et al.
TABLE III Oxidation of Sulfides to Sulfoxides Using
(BunPPh3)2Cr2O7/AlCl3
Time (min)
Solutiona MWb Solution MW
Yield (%)c
Sulfide (1)
Sulfoxide (2)
(C6H5)2SO (2a)
C6H5CH2SOC6H5 (2b)
(C6H5CH2)2SO (2c)
4-MeC6H4CH2SOC6H5 (2d)
4-BrC6H4CH2SOC6H5 (2e)
4-O2NC6H4CH2SOC6H5 (2f)
4-MeC6H4SOCH2C6H5 (2g)
4-BrC6H4SOCH2C6H5 (2h)
4-ClC6H4SOCH2C6H5 (2i)
4-BrC6H4CH2SOCH2C6H5 (2j)
(C6H5)2S (1a)
C6H5CH2SC6H5 (1b)
(C6H5CH2)2S (1c)
200
90
5
2
92
93
93
93
94
95
94
95
93
94
93
92
95
85
92
85
88
93
92
94
95
94
96
96
95
95
94
95
95
94
94
86
93
85
85
94
60
1
4-MeC6H4CH2SC6H5 (1d)
4-BrC6H4CH2SC6H5 (1e)
4-O2NC6H4CH2SC6H5 (1f)
4-MeC6H4SCH2C6H5 (1g)
4-BrC6H4SCH2C6H5 (1h)
4-ClC6H4SCH2C6H5 (1i)
4-BrC6H4CH2SCH2C6H5 (1j)
4-BrC6H4CH2SC6H44-Me (1k) 4-BrC6H4CH2SOC6H44-Me (2k)
4-BrC6H4CH2SC6H44-Br (11) 4-BrC6H4CH2SOC6H44-Br (2l)
4-BrC6H4CH2SC6H44-Cl (1m) 4-BrC6H4CH2SOC6H44-Cl (2m)
4-O2NC6H4CH2SC6H44-Cl (1n) 4-O2NC6H4CH2SOC6H44-Cl (2n)d
90
2
70
55
1.25
1
60
1
115
180
60
2.5
4
1
70
90
1.25
2
120
100
180
40
2.5
2
4
0.75
1
2-ClC6H4CH2SC6H44-Cl (1o)
(n-C3H7)2S (1p)
(n-C4H9)2S (1q)
2-ClC6H4CH2SOC6H44-Cl (2o)
(n-C3H7)2SO (2p)d
(n-C4H9)2SO (2q)d
60
n-C8H17SCH2CH2CHMe2 (1r) n-C8H17SOCH2CH2CHMe2 (2r)
220
5.25
240
5.5
86
85
aSulfide: BTPPDC: AlCl3 = 1:1.5:1.
bSulfide: BTPPDC: AlCl3 = 1:1.5:1.
cIsolated yields.
d3–10% of sulfone was obtained from the reaction mixture.
solution and under microwave irradiation. The optimum molar ratios
of sulfide to BTPPDC to AlCl3 in solution and under microwave irradia-
tion were found to be 1:2–3:1 and 1:1.5–2.5:1, respectively. When a wide
range of diaryl, dialkyl, dibenzyl, aryl benzyl, alkyl aryl, and cyclic sul-
fides 1a–z, 1aꢀ–dꢀ were treated with BTPPDC in the presence of AlCl3
in refluxing acetonitrile, the corresponding sulfones 3a–z and 3aꢀ–dꢀ
were obtained in 92–96% yields. The reaction time usually is between
30–270 min. Under microwave irradiation, these sulfides were oxidized
to their corresponding sulfones in 93–98% yields with reaction periods
ranging between 0.75–5.5 min (Table IV). Under microwave irradia-
tion, acetonitrile was used for homogenization of the reaction mixture.
The polar character of this solvent also seems to increase the reaction
temperature, so the reaction is completed in a short time.31c The re-
sults show that the yields of the products are comparable in solution
and under microwave irradiation, but the reaction times considerably
are shorter under microwave irradiation (Tables III and IV). Also the
molar ratio of BTPPDC to sulfide is lower under microwave irradiation.

Oxidation of Sulfides to Sulfoxides and Sulfones
2755
It is noteworthy that sulfides containing functional groups such as
alkene and ketone are oxidized selectively without any interference
from these groups (Table IV, entries 1t, 1cꢀ, and 1dꢀ). We also have
monitored competitive oxidation of sulfides in the presence of oxime,
aldehyde, ether, and acetal. The results are demonstrated in Scheme 2.
These observations clearly show that the method is applicable for the
selective oxidation of sulfides in the presence of the previously men-
tioned functional groups and can be considered as a useful practical
achievement in oxidtion of sulfides to sulfoxides and sulfones.
In Table V, the results of the oxidation of benzyl phenyl sulfide (1b)
to benzyl phenyl sulfoxide (2b) and benzyl phenyl sulfone (3b) by our
method are compared with those reported by other methods. As can be
seen, this method is superior to some previously reported methods in
terms of yields, reaction times, and the amount of the reagent used for
successful oxidation.
SCHEME 2

2756
I. Mohammadpoor-Baltork et al.
TABLE IV Oxidation of Sulfides to Sulfones Using
(BunPPh3)2Cr2O7/AlCl3
Time (min)
Solutiona MWb Solution MW
Yield (%)c
Sulfide (1)
Sulfone (3)
(C6H5)2S (1a)
C6H5CH2SC6H5 (1b)
(C6H5CH2)2S (1c)
(C6H5)2SO2 (3a)
C6H5CH2SO2C6H5 (3b)
(C6H5CH2)2SO2 (3c)
4-MeC6H4CH2SO2C6H5 (3d)
4-BrC6H4CH2SO2C6H5 (3e)
4-O2NC6H4CH2SO2C6H5 (3f)
4-MeC6H4SO2CH2C6H5 (3g)
4-BrC6H4SO2CH2C6H5 (3h)
4-ClC6H4SO2CH2C6H5 (3i)
4-BrC6H4CH2SO2CH2C6H5 (3j)
180
100
80
65
90
4.5
2.5
2
1
2
2
2.5
3
95
96
95
96
93
95
93
95
93
96
93
94
94
92
95
93
96
94
96
97
96
98
96
97
93
96
93
96
95
96
97
94
96
94
95
95
4-MeC6H4CH2SC6H5 (1d)
4-BrC6H4CH2SC6H5 (1e)
4-O2NC6H4CH2SC6H5 (1f)
4-MeC6H4SCH2C6H5 (1g)
4-BrC6H4SCH2C6H5 (1h)
4-ClC6H4SCH2C6H5 (1i)
4-BrC6H4CH2SCH2C6H5 (1j)
4-BrC6H4CH2SC6H44-Me (1k) 4-BrC6H4CH2SO2C6H44-Me (3k)
4-BrC6H4CH2SC6H44-Br (1l) 4-BrC6H4CH2SO2C6H44-Br (3l)
4-BrC6H4CH2SC6H44-Cl (1m) 4-BrC6H4CH2SO2C6H44-Cl (3m)
4-O2NC6H4CH2SC6H44-Cl (1n) 4-O2NC6H4CH2SO2C6H44-Cl (3n)
70
100
120
150
45
100
130
125
75
180
75
130
200
3
0.75
2.5
4
3
1.5
4
1.5
3
5
2-ClC6H4CH2SC6H44-Cl (1o)
(n-C3H7)2S (1p)
(n-C4H9)2S (1q)
2-ClC6H4CH2SO2C6H44-Cl (3o)
(n-C3H7)2SO2 (3p)
(n-C4H9)2SO2 (3q)
n-C8H17SCH2CH2CHMe2 (1r) n-C8H17SO2CH2CH2CHMe2 (3r)
240
5
95
95
270
90
5.5
2
92
95
93
94
n-C8H17SCH2CH3 (1v)
C6H5SMe (1w)
4-MeC6H4SMe (1x)
4-ClC6H4SMe (1y)
C6H5S(n-C3H7) (1z)
C6H5S(n-C4H9) (1aꢀ)
C6H5SCHMe2 (1bꢀ)
C6H5SCH2CH=CH2 (1cꢀ)
(CH2=CHCH2)2S (1dꢀ)
n-C8H17SO2CH2CH3 (3v)
C6H5SO2Me (3w)
100
40
30
120
75
90
120
45
40
2.5
1
0.75
3
1.5
2
3
94
94
96
94
96
94
93
94
95
95
95
97
96
97
95
94
94
95
4-MeC6H4SO2Me (3x)
4-ClC6H4SO2Me (3y)
C6H4SO2(n-C3H7) (3z)
C6H5SO2(n-C4H9) (3aꢀ)
C6H5SO2CHMe2 (3bꢀ)
C6H5SO2CH2CH=CH2 (3cꢀ)
(CH2=CHCH2)2SO2 (3dꢀ)
1
0.75
aSulfide: BTPPDC: AlCl3 = 1:3:1 and 1:2:1 for entries 1a–1v and 1w–1dꢀ, respectively.
bSulfide: BTPPDC: AlCl3 = 1:2.5:1 and 1:1.5:1 for entries 1a–1v and 1w–1dꢀ,
respectively.
cIsolated yield.
In conclusion the results presented in this article demonstrate that
BTPPDC/AlCl3 can be used for the efficient and selective oxidation
of sulfides to sulfoxides and sulfones. Short reaction times, excellent
yields, easy workup, easy preparation, and low cost of the reagent are

Oxidation of Sulfides to Sulfoxides and Sulfones
2757
TABLE V Comparison of Oxidation of Benzyl Phenyl Sulfide
(1b) to Benzyl Phenyl Sulfoxide (2b) and Benzyl Phenyl
Sulfone (3b) by BTPPDC/AlCl3 with Some of Those Reported
in the Literature
Reagen (oxidant/substrate)
Product Yield % (Time, min)
BTPPDC/AlCl3/CH3CN/reflux (1.5:1)
BTPPDC/AlCl3/MW (1.2:1)
2b
2b
2b
2b
2b
2b
3b
3b
3b
3b
3b
93 (90)
94 (2)
NaIO4/wet SiO2/MW (1.7:1)30 f
PhCH2PPh3HSO5/CH3CN/reflux (1.5:1)18b
Ba(MnO4)2/CH3CN/reflux (6:1)21a
CAN/wet SiO2/CH2Cl2/rt (2:1)8
BTPPDC/AlCl3/CH3CN/reflux (3:1)
BTPPDC/AlCl3/MW (2.5:1)
83 (2.5)
88 (12 h)
88 (4 h)
96 (45)
96 (100)
97 (2.5)
87 (2.5)
94 (75)
97 (30)
NaIO4/wet SiO2/MW (3:1)30 f
MMPP/wet SiO2/CH2Cl2/reflux (3:1)27
Oxone/AlCl3/solvent-free (4:1)18a
other noteworthy advantages of this method. Moreover, wide applica-
bility and also excellent chemoselectivity make this reagent system a
good choice for the use in the oxidation of sulfides.
EXPERIMENTAL
General
The sulfides 1a, 1p, 1q, 1s, 1t, and 1dꢀ were purchased from Merck
chemical company. The other sulfides were prepared according to the
described procedure.34 The yields refer to isolated pure products. Melt-
ing points were determined using a Mettler FP5 apparatus and are
uncorrected. IR spectra were run on a Philips PU9716 spectropho-
1
tometer. H NMR spectra were recorded on a Bruker 80 or 200 and
or 500 MHz spectrometer in CDCl3 as the solvent and TMS as internal
standard. The elemental analysis was performed by Research Institute
of Petroleum Industry, Tehran, Iran. BTPPDC was prepared according
to the reported procedure.32a
Oxidation of Sulfides 1a–s to Sulfoxides 2a–s in Acetonitrile,
General Procedure
To a solution of sulfide 1 (1 mmol) in CH3CN (10 mL) in a round-
bottomed flask (50 mL) equipped with a condenser and a magnetic
stirrer, BTPPDC (1.28 g, 1.5 mmol) and AlCl3 (0.134 g, 1 mmol) were

2758
I. Mohammadpoor-Baltork et al.
added and refluxed for 40–240 min. The progress of the reaction was
followed by TLC (eluent: n-hexane/ethyl acetate, 7:2). The mixture was
filtered and the solid material was washed with CH3CN (15 mL). The
filtrate was evaporated and the resulting crude material was purifided
by recrystallization or chromatography on silica-gel to afford the pure
sulfoxide 2a–s in 85–95% yields (Table III).
Oxidation of Sulfides 1a–s to Sulfoxides 2a–s Under
Microwave Irradiation, General Procedure
A mixture of sulfide 1 (1 mmol), BTPPDC (1.028 g, 1.2 mmol) and
AlCl3 (0.134 g. 1 mmol) was prepared. CH3CN (2 mL) was added and
the mixture was exposed to microwave irradiation (900 W) for 0.75–
5.5 min. The progress of the reaction was monitored by TLC (eluent:
n-hexane/ethyl acetate, 7:2). After completion of the reaction, the mix-
ture was extracted with ethyl acetate (2 × 20 mL). Evaporation of the
solvent followed by recrystallization or chromatography on silica-gel
afforded the pure sulfoxide 2a–s in 85–96% yields (Table III).
Oxidation of Sulfides 1a–z, 1aꢀ–dꢀ to Sulfones 3a–z, 3aꢀ-dꢀ
in Acetonitrile, General Procedure
In a round-bottomed flask equipped with a condenser and a magnetic
stirrer, a solution of sulfide 1 (1 mmol) in CH3CN (10 mL) was prepared.
BTPPDC (2–3 mmol) and AlCl3 (1 mmol) were added to the solution and
the mixture was refluxed for 30–270 min. The progress of the reaction
was followed by TLC (eluent: n-hexane/ethyl acetate, 7:1). The reaction
mixture was filtered and the solid material was washed with CH3CN
(15 mL). The filtrate was evaporated and the crude product was either
recrystallized or purified by chromatography on silica-gel to afford the
pure sulfone 3a–z, 3aꢀ-dꢀ in 92–96% yields (Table IV).
Oxidation of Sulfides 1a–z, 1aꢀ–dꢀ to Sulfones 3a–z, 3aꢀ–dꢀ
Under Microwave Irradiation, General Procdure
A mixture of sulfide 1 (1 mmol), BTPPDC (1.5–2.5 mmol), AlCl3
(1 mmol) and CH3CN (2 mL) was irradiated in a microwave oven (900 W)
for 0.75–5.5 min. After completion of the reaction as indicated by TLC
(eluent: n-hexane/ethyl acetate, 7:1), the reaction mixture was extracted
with ethyl acetate (2 × 20 mL). The solvent was evaporated and the re-
sulting crude material was purified by recrystallization or chromatog-
raphy on silica-gel to afford the pure sulfone 3a–z, 3aꢀ–dꢀ in 93–98%
yields (Table IV).
The physical and spectral data of the products are as follows.

Oxidation of Sulfides to Sulfoxides and Sulfones
2759
Diphenyl Sulfoxide (2a)
M.p. 70–72◦C (lit.2 m.p. 69–72◦C). IR (KBr): ν = 1038 cm−1. 1H NMR
(200 MHz, CDCl3): δ = 7.41–7.50 (m, 6H), 7.61–7.66 (m, 4H).
Benzyl Phenyl Sulfoxide (2b)
M.p. 122–123◦C (lit.2 m.p. 122–123◦C). IR (KBr): ν = 1034 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 4.04 (d, 1H, J = 12.6 Hz), 4.14 (d, 1H,
J = 12.6 Hz), 7.02–7.03 (m, 2H), 7.28–7.36 (m, 3H), 7.41–7.52 (m, 5H).
Dibenzyl Sulfoxide (2c)
M.p. 131–133◦C (lit.2 m.p. 132–134◦C). IR (KBr): ν = 1026 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 3.91 (d, 2H, J = 13.0 Hz), 3.98 (d, 2H,
J = 13.0 Hz), 7.31–7.41 (m, 10H).
4-Methylbenzyl Phenyl Sulfoxide (2d)
M.p. 97–99◦C (lit.35a m.p. 99–100◦C). IR (KBr): ν = 1027 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 2.36 (s, 3H), 3.99 (d, 1H, J = 12.6 Hz),
4.10 (d, 1H, J = 12.6 Hz), 6.91 (d, 2H, J = 7.70 Hz), 7.10 (d, 2H,
J = 7.70 Hz), 7.42–7.51 (m, 5H).
4-Bromobenzyl Phenyl Sulfoxide (2e)
M.p. 178–179◦C (lit.35b m.p. 179◦C). IR (KBr): ν = 1029 cm−1
.
1H NMR (200 MHz, CDCl3): δ = 3.98 (d, 1H, J = 12.8 Hz), 4.05 (d, 1H,
J = 12.8 Hz), 6.86 (d, 2H, J = 8.3 Hz), 7.31–7.51 (m, 7H).
4-Nitrobenzyl Phenyl Sulfoxide (2f)
M.p. 161–163◦C. IR (KBr): ν = 1515, 1345, 1026 cm−1. 1H NMR (200
MHz, CDCl3): δ = 4.04 (d, 1H, J = 12.0 Hz), 4.24 (d, 1H, J = 12.0 Hz),
7.13 (d, 2H, J = 6.5 Hz), 7.40–7.51 (m, 5H), 8.12 (d, 2H, J = 6.5 Hz).
Anal. calcd. for C13H11NSO3: C, 59.76; H, 4.24; N, 5.36; S, 12.27. Found:
C, 59.63; H, 4.40; N, 5.25; S, 12.41.
Benzyl 4-Methylphenyl Sulfoxide (2g)
M.p. 121–123◦C (lit.30b m.p. 122–124◦C). IR (KBr): ν = 1024 cm−1
.
1H NMR (200 MHz, CDCl3): δ = 2.40 (s, 3H), 4.0 (d, 1H, J = 12.5 Hz),
4.10 (d, 1H, J = 12.5 Hz), 7.01–7.05 (m, 2H), 7.28–7.32 (m, 7H).
Benzyl 4-Bromophenyl Sulfoxide (2h)
M.p. 139–140◦C (lit.35b m.p. 141–142◦C). IR (KBr): ν = 1034 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 4.0 (d, 1H, J = 12.6 Hz), 4.1 (d, 1H,
J = 12.6 Hz), 7.0 (d, 2H, J = 8.38 Hz), 7.24 (d, 2H, J = 8.38), 7.29–7.34
(m, 3H), 7.60 (d, 2H, J = 8.38 Hz).

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Benzyl 4-Chlorophenyl Sulfoxide (2i)
M.p. 120–122◦C (lit.30b m.p. 120–122◦C). IR (KBr): ν = 1036
cm−1. 1H NMR (200 MHz, CDCl3): δ = 4.02 (d, 1H, J = 12.5 Hz), 4.15
(d, 1H, J = 12.5 Hz), 7.02 (d, 2H, J = 6.8 Hz), 7.26–7.46 (m, 5H), 7.36 (d,
2H, J = 6.8 Hz).
Benzyl 4-Bromobenzyl Sulfoxide (2j)
M.p. 139–140◦C. IR (KBr): ν = 1028 cm−1
.
1H NMR (500 MHz,
CDCl3): δ = 3.78 (d, 1H, J = 13.09 Hz), 3.89 (d, 1H, J = 13.09 Hz), 3.95
(s. 2H), 7.2 (d, 2H, J = 8.27 Hz), 7.32–7.33 (m, 2H), 7.40–7.44 (m, 3H),
7.54 (d, 2H, J = 8.27 Hz). Anal. calcd. for C14H13SOBr: C, 54.38; H, 4.24;
S, 10.37. Found: C, 54.30; H, 4.22, S, 10.50.
4-Bromobenzyl 4-Methylphenyl Sulfoxide (2k)
M.p. 159–161◦C (lit.35 m.p. 161◦C). IR (KBr): ν = 1030 cm−1. 1H NMR
(500 MHz, CDCl3): δ = 2.46 (s, 3H), 3.99 (s, 2H), 6.88 (d, 2H, J = 8.2 Hz),
7.27–7.31 (m, 4H), 7.42 (d, 2H, J = 8.2 Hz).
4-Bromobenzyl 4-Bromophenyl Sulfoxide (2l)
M.p. 143–145◦C (lit.35b m.p. 145–146◦C). IR (KBr): ν = 1038 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 3.98 (d, 1H, J = 12.73 Hz), 4.02 (d,
1H, J = 2.73 Hz), 6.88 (d, 2H, J = 8.0 Hz), 7.26 (d, 2H, J = 8.0 Hz), 7.45
(d, 2H, J = 8.0 Hz), 7.62 (d, 2H, J = 8.0 Hz).
4-Bromobenzyl 4-Chlorophenyl Sulfoxide (2m)
M.p. 134–136◦C (lit.35b m.p. 135–136◦C). IR (KBr): ν = 1037 cm−1
.
1H NMR (200 MHz, CDCl3): δ = 3.98 (d, 1H, J = 12.85 Hz), 4.05 (d, 1H,
J = 12.85 Hz), 6.87 (d, 2H, J = 8.40 Hz), 7.30 (d, 2H, J = 8.40 Hz), 7.45–
7.51 (m, 4H).
4-Chlorophenyl 4-Nitrobenzyl Sulfoxide (2n)
M.p. 154–155◦C (lit.35c m.p. 153.5–154.5◦C). IR (KBr): ν = 1515, 1345,
1040 cm−1. 1H NMR (500 MHz, CDCl3): δ = 4.04 (d, 1H, J = 12.83 Hz),
4.24 (d, 1H, J = 12.83 Hz), 7.17 (d, 2H, J = 8.53 Hz), 7.33 (d, 2H,
J = 8.53 Hz), 7.48 (d, 2H, J = 8.53 Hz), 8.17 (d, 2H, J = 8.53 Hz).
2-Chlorobenzyl 4-Chlorophenyl Sulfoxide (2o)
M.p. 73–74◦C (lit.35b m.p. 73–74◦C). IR (KBr): ν = 1040 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 4.20 (d, 1H, J = 12.56 Hz), 4.30 (d, 1H,
J = 12.56 Hz), 7.16 (d, 2H, J = 7.05 Hz), 7.25 (t, 2H, J = 7.40 Hz), 7.41
(d, 2H, J = 8.5 Hz), 7.47 (d, 2H, J = 8.5 Hz).

Oxidation of Sulfides to Sulfoxides and Sulfones
2761
Dipropyl Sulfoxide (2p)
Oil (lit.34 oil). IR (neat): ν = 1020 cm−1. 1H NMR (200 MHz, CDCl3):
δ = 1.10 (t, 6H, J = 7.2 Hz), 1.81–1.98 (m, 4H), 2.50–2.74 (m, 4H).
Dibutyl Sulfoxide (2q)
Oil (lit.35i oil). IR (neat): ν = 1022 cm−1. 1H NMR (200 MHz, CDCl3):
δ = 0.92 (t, 6H, J = 7.2 Hz), 1.41–1.56 (m, 4H), 1.70–1.80 (m, 4H), 2.58–
2.73 (m, 4H).
3-Methylbutyl n-Octyl Sulfoxide (2r)
M.p. 42–43◦C. IR (KBr): ν = 1018 cm−1. 1H NMR (200 MHz, CDCl3):
δ = 0.88–0.94 (m, 9H), 1.15–1.50 (m, 10H), 1.60–1.90 (m, 5H), 2.55–2.80
(m, 4H). Anal. calcd. for C13H28SO: C, 67.18; H, 12.14; S, 13.80. Found:
C, 66.98; H, 12.08; S, 14.10.
Dibenzothiophene Sulfoxide (2s)
M.p. 181–183◦C (lit.2 m.p. 181–183◦C). IR (KBr): ν = 1038 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 7.53–7.70 (m, 4H), 7.83–8.04 (m, 4H).
Diphenyl Sulfone (3a)
M.p. 125–126◦C (lit.35i m.p. 126–128◦C). IR (KBr): ν = 1304,
1150 cm−1. 1H NMR (80 MHz, CDCl3): δ = 7.40–7.60 (m, 6H), 7.85–8.04
(m, 4H).
Benzyl Phenyl Sulfone (3b)
M.p. 146–147◦C (lit.30a m.p. 146–147◦C). IR (KBr): ν = 1284,
1120 cm−1. 1H NMR (200 MHz, CDCl3): δ = 4.35 (s, 2H), 7.10–7.14 (m,
2H), 7.30–7.37 (m, 3H), 7.44–7.69 (m, 5H).
Dibenzyl Sulfone (3c)
M.p. 148–149◦C (lit.34 m.p. 150◦C). IR (KBr): ν = 1300, 1122 cm−1
1H NMR (200 MHz, CDCl3): δ = 4.17 (s, 4H), 7.39–7.44 (m, 10H).
.
4-Methylbenzyl Phenyl Sulfone (3d)
M.p. 150–152◦C (lit.35d m.p. 151–152◦C). IR (KBr): ν = 1298,
1
1137 cm−1. H NMR (500 MHz, CDCl3): δ = 2.36 (s, 3H), 4.31 (s, 2H),
7.0 (d, 2H, J = 7.9 Hz), 7.11 (d, 2H, J = 7.9 Hz), 7.50 (t, 2H, J = 7.8 Hz),
7.64 (t, 1H, J = 7.48 Hz), 7.68–7.69 (m, 2H).

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4-Bromobenzyl Phenyl Sulfone (3e)
M.p. 195–197◦C (lit.35d m.p. 191–193◦C). IR (KBr): ν = 1300,
1
1143 cm−1. H NMR (200 MHz, CDCl3): δ = 4.37 (s, 2H), 6.99 (d, 2H,
J = 8.5 Hz), 7.42–7.80 (m, 7H).
4-Nitrobenzyl Phenyl Sulfone (3f)
M.p. 204–205◦C. IR (KBr): ν = 1515, 1345, 1300, 1142 cm−1. 1H NMR
(200 MHz, CDCl3): δ = 4.44 (s, 2H), 7.10 (d, 2H, J = 6.5 Hz), 7.40–7.70
(m, 5H), 8.18 (d, 2H, J = 6.5 Hz). Anal. calcd. for C13H11NSO4: C, 56.31;
H, 3.99; N, 5.05; S, 11.56. Found: C, 56.17; H, 4.10; N, 4.96; S, 11.75.
Benzyl 4-Methylphenyl Sulfone (3g)
M.p. 143-144◦C (lit.30b m.p. 142–144◦C). IR (KBr): ν = 1308,
1
1144 cm−1. H NMR (200 MHz, CDCl3): δ = 2.40 (s, 3H), 4.27 (s, 2H),
7.0-7.35 (m, 5H), 7.40–7.60 (m, 4H).
Benzyl 4-Bromophenyl Sulfone (3h)
M.p. 156–158◦C (lit.35b m.p. 158–159◦C). IR (KBr): ν = 1305,
1
1140 cm−1. H NMR (500 MHz, CDCl3): δ = 4.35 (s, 2H), 7.13 (d, 2H,
J = 7.2 Hz), 7.31–7.38 (m, 3H), 7.50 (d, 2H, J = 8.5 Hz), 7.62 (d, 2H,
J = 8.5 Hz).
Benzyl 4-Chlorophenyl Sulfone (3i)
M.p. 142–143◦C (lit.30b m.p. 142–145◦C). IR (KBr): ν = 1310,
1
1143 cm−1. H NMR (200 MHz, CDCl3)δ = 4.35 (s, 2H), 7.13 (d, 2H,
J = 6.7 Hz), 7.31–7.6 (m, 5H), 7.72 (d, 2H, J = 6.7 Hz).
Benzyl 4-Bromobenzyl Sulfone (3j)
1
M.p. 176–178◦C. IR (KBr): ν = 1299, 1116 cm−1. H NMR (80 MHz,
CDCl3): δ = 4.02 (s, 2H), 4.14 (s, 2H), 7.17–7.60 (m, 9H). Anal. calcd.
for C14H13BrSO2: C, 51.70; H, 4.03; S, 9.86. Found: C, 51.60; H, 4.10; S,
9.97.
4-Bromobenzyl 4-Methylphenyl Sulfone (3k)
M.p. 172–173◦C (lit.35c m.p. 171–172◦C). IR (KBr): ν = 1299,
1
1140 cm−1. H NMR (80 MHz, CDCl3): δ = 2.41 (s, 3H), 4.24 (s, 2H),
7.0 (d, 2H, J = 8.2 Hz), 7.27–7.31 (m, 4H), 7.42 (d, 2H, J = 8.2 Hz).
4-Bromobenzyl 4-Bromophenyl Sulfone (3l)
M.p. 179–180◦C (lit.35b m.p. 179–180◦C). IR (KBr): ν = 1304,
1
1144 cm−1. H NMR (500 MHz, CDCl3): δ = 4.29 (s, 2H), 7.02 (d, 2H,

Oxidation of Sulfides to Sulfoxides and Sulfones
2763
J = 8.45 Hz), 7.47 (d, 2H, J = 8.45 Hz), 7.53 (d, 2H, J = 8.45 Hz), 7.67 (d,
2H, J = 8.45 Hz).
4-Bromobenzyl 4-Chlorophenyl Sulfone (3m)
M.p. 157–158◦C (lit.35b m.p. 158–159◦C). IR (KBr): ν = 1303,
1
1144 cm−1. H NMR (200 MHz, CDCl3): δ = 4.29 (s, 2H), 7.01 (d, 2H,
J = 8.26 Hz), 7.25–7.63 (m, 6H).
4-Chlorophenyl 4-Nitrobenzyl Sulfone (3n)
M.p. 174–175◦C (lit.35c m.p. 175–176◦C). IR (KBr): ν = 1515, 1345,
1300, 1140 cm−1. 1H NMR (500 MHz, CDCl3): δ = 4.44 (s, 2H), 7.37 (d,
2H, J = 8.6 Hz), 7.52 (d, 2H, J = 8.6 Hz), 7.64 (d, 2H, J = 8.6 Hz), 8.21
(d, 2H, J = 8.6 Hz).
2-Chlorobenzyl 4-Chlorophenyl Sulfone (3o)
M.p. 120–121◦C (lit.35b m.p. 120–121◦C). IR (KBr): ν = 1310,
1130 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 4.60 (s, 2H), 7.28–7.36
(m, 3H), 7.45 (d, 2H, J = 7.76 Hz), 7.49–7.54 (m, 1H), 7.59 (d, 2 H,
J = 7.76 Hz).
Dipropyl Sulfone (3p)
1
Oil (lit.34 oil). IR (neat): ν = 1269, 1130 cm−1. H NMR (500 MHz,
CDCl3): δ = 1.06 (t, 6H, J = 7.5 Hz), 1.79–1.85 (m, 4H), 2.88 (t, 4H,
J = 7.96 Hz).
Dibutyl Sulfone (3q)
M.p. 44–45◦C (lit.35i m.p. 43–45◦C). IR (KBr): ν = 1259, 1120 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 1.01 (t, 6H, J = 7.36 Hz), 1.48–1.57 (m,
4H), 1.82–1.88 (m, 4H), 2.97 (t, 4H, J = 8.10 Hz).
3-Methylbutyl n-Octyl Sulfone (3r)
1
M.p. 39–41◦C. IR (KBr): ν = 1266, 1110 cm−1. H NMR (80 MHz,
CDCl3): δ = 0.80–1.90 (m, 24 H), 2.65–2.90 (m, 4 H). Anal. calcd. for
C13H28SO2: C, 62.85; H, 11.36; S, 12.91. Found: C, 62.70; H, 11.45;
S, 13.10.
Dibenzothiophene Sulfone (3s)
M.p. 232–234◦C (lit.35i m.p. 231–233◦C). IR (KBr): ν = 1282,
1160 cm−1. 1H NMR (80 MHz, CDCl3): δ = 7.04–7.60 (m, 4H), 7.62–7.90
(m, 4H).

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Thioxanthen-9-One 10,10-Dioxide (3t)
M.p. 186–187◦C (lit.35g m.p. 187–188◦C). IR (KBr): ν = 1677, 1290,
1
1158 cm−1. H NMR (500 MHz, CDCl3): δ = 7.84–7.93 (m, 4H), 8.22–
8.40 (m, 4H).
Methyl n-Ocyl Sulfone (3u)
1
M.p. 63–64◦C. IR (KBr): ν = 1275, 1122 cm−1. H NMR (80 MHz,
CDCl3): δ = 0.80–1.85 (m, 15H), 2.70–3.0 (m, 5H). Anal. calcd. for
C9H20SO2: C, 56.21; H, 10.48; S, 16.67. Found: C, 56.15; H, 10.40;
S, 16.85.
Ethyl n-Octyl Sulfone (3v)
1
M.p. 66–67◦C. IR (KBr): ν = 1272, 1114 cm−1. H NMR (80 MHz,
CDCl3): δ = 0.80–1.85 (m, 18H), 2.65–3.0 (m, 4H). Anal. calcd. for
C10H22SO2: C, 58.21; H, 10.74; S, 15.54. Found: C, 58.20; H, 10.70;
S, 15.65.
Methyl Phenyl Sulfone (3w)
M.p. 84–85◦C (lit.30b m.p. 85–86◦C). IR (KBr): ν = 1295, 1140 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 3.10 (s, 3H), 7.61–7.72 (m, 3H), 7.99–8.0
(m, 2H).
Methyl 4-Methylphenyl Sulfone (3x)
M.p. 84–86◦C (lit.35h m.p. 85–87◦C). IR (KBr): ν = 1314, 1139 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 2.49 (s, 3H), 3.07 (s, 3H), 7.40 (d, 2H,
J = 8.0 Hz), 7.86 (d, 2H, J = 8.0 Hz).
4-Chlorophenyl Methyl Sulfone (3y)
1
M.p. 95–97◦C. IR (KBr): ν = 1304, 1142 cm−1. H NMR (500 MHz,
CDCl3): δ = 3.10 (s, 3H), 7.60 (d, 2H, J = 8.5 Hz), 7.90 (d, 2H, J = 8.5 Hz).
Anal. calcd. for C7H7ClSO2: C, 44.10; H, 3.70; S, 16.82. Found: C, 43.90;
H, 3.80; S, 17.10.
Phenyl n-Propyl Sulfone (3z)
M.p. 44–45◦C (lit.35e m.p. 46◦C). IR (KBr): ν = 1304, 1140 cm−1
.
1H NMR (500 MHz, CDCl3): δ = 1.06 (t, 3H, J = 6 Hz), 1.71–1.84 (m,
2H), 3.10 (t, 2H, J = 6 Hz), 7.53–7.60 (m, 3H), 7.93–7.94 (m, 2H).
n-Butyl Phenyl Sulfone (3aꢀ)
1
Oil (lit.35e oil). IR (neat): ν = 1300, 1140 cm−1. H NMR (500 MHz,
CDCl3): δ = 0.96 (t, 3H, J = 6 Hz), 1.44–1.73 (m, 4H), 3.10 (t, 2H,
J = 6 Hz), 7.53–7.60 (m, 3H), 7.93–7.94 (m, 2H).

Oxidation of Sulfides to Sulfoxides and Sulfones
2765
Phenyl 2-Propyl Sulfone (3bꢀ)
1
Oil (lit.35e oil). IR (neat): ν = 1300, 1140 cm−1. H NMR (500 MHz,
CDCl3): δ = 1.31 (d, 6H, J = 6.3 Hz), 3.14 (q, 1H, J = 6.2 Hz), 7.49–7.60
(m, 3H), 7.88–7.89 (m, 2H).
Allyl Phenyl Sulfone (3cꢀ)
Oil (lit.30b oil). IR (neat): ν = 1667, 1307, 1140 cm−1
.
1H NMR
(500 MHz, CDCl3): δ = 3.80 (d, 2H, J = 7 Hz), 5.16 (d, 1H, J = 17 Hz),
5.36 (d, 1H, J = 10.2 Hz), 5.74–5.86 (m, 1H), 7.40–7.65 (m, 5H).
Diallyl Sulfone (3d ꢀ)
Oil (lit.35f oil). IR (neat): ν = 1639, 1314, 1124 cm−1
.
1H NMR
(500 MHz, CDCl3): δ = 3.70 (d, 4H, J = 7.30 Hz), 5.40–5.54 (m, 4H),
5.90–6.0 (m, 2H).
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