Sodium sulfate-hydrogen peroxide-sodium chloride adduct: selective protocol for the oxidative bromination, iodination and temperature dependent oxidation of sulfides to sulfoxides and sulfones

Article abstract of DOI:10.1039/C8NJ06038J

The regioselective bromination and iodination of unprotected aromatic primary amines using enclathrated hydrogen peroxide as an oxidant under mild conditions has been developed, in which potassium bromide (KBr) and potassium iodide (KI) were used as brominating and iodinating agents, respectively. The adduct shows not only regioselectivity for para- or ortho-isomers but also a remarkable chemoselectivity for monobromination. Selective oxidation of sulfides to sulfoxides and sulfones has also been studied and good to excellent yields of the desired products were obtained. Acetic acid was found to be the solvent of choice for these reactions. This simple method represents an ecologically benign and alternative pathway for the oxidative halogenation of anilines and the oxidation of sulfides to sulfoxides and sulfones.

Full text of DOI:10.1039/C8NJ06038J

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PAPER
Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
diarylethene-based metal–organic frameworks
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DOI: 10.1039/C8NJ06038J
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Sodium sulfate-Hydrogen peroxide-Sodium chloride adduct:
Selective Protocol for, Oxidative bromination, iodination and
temperature dependent oxidation of sulfide to sulfoxide and
sulfones
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Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Eknath M. Gayakwada, Khushbu P. Patela, and Ganapati S. Shankarlinga*
www.rsc.org/
Abstract
The regioselective bromination and iodination of unprotected aromatic primary amines using enclathrated hydrogen
peroxide as an oxidant under mild conditions has been developed, in which potassium bromide (KBr) and potassium iodide
(KI) are used as a brominating and iodinating agents respectively. The adduct shows not only regioselectivity for para- or
ortho- isomers but also a remarkable chemoselectivity for monobromination. Selective oxidation of sulfide to sulfoxide and
sulfone has been also studied and obtained good to excellent yields of desired products. Acetic acid was found to be the
best solvent of choice for these reactions. These simple methods represent ecologically benign and alternative pathway for
oxidative halogination of aniline and oxidation of sulfide to sulfoxide and sulfone.
for the selective bromination of aniline20. Moreover, Controlled
bromination of alkylated anilines was also performed using a
Introduction
surfactant as
homogeneous medium at different
Halogenated aromatic compounds are versatile synthetic
intermediates for several organic reactions ranging from C-C
bond formation1,2 to that of organometallic reagents. They are
temperatures21–23
.
Iodinated aromatic compounds have attracted much attention.
recently, due to its wide range of applications in C-C, C-N, C-O,
and C-S bond formation.24 They are also used for synthesis of
human and animal medicines25. Several methodologies have
been reported in the literature for the oxidative iodination of
aniline such as, oxone-NH4I26, iodine-HgO27, Iodine-Ag2SO4
Iodine-Cr2O329, Potassium iodide-HIO4 in H2SO430, 30% H2O2–KI–
H2SO4–MeOH31, VO(acac)2-H2O2-NaI32, potassium iodide in
sulphuric acid33, Iodine-potassium iodide-Hg(OAc)234, NaOCl-
NaI35, NIS-CF3SO3H36, NIS-CF3COOH37. Most of these procedures
suffer from the uncontrolled bromination and iodination at the
aromatic nucleus, therefore, the regioselective bromination
and iodination of anilines are still demanding.
used as precursors in pharmaceuticals, dyes, agrochemicals
3–5
industries
and also serve as a significant candidate for the
synthesis of many biologically active molecules such as
antitumor, antibacterial, antiviral, antineoplastic, antioxidizing
agent,6–8 etc. In recent years, several methods have been
reported in the literature for the regioselective bromination and
iodination of aromatic primary amines but, oxidative
halogenation of aromatic compounds signifies environmentally
benign, selective pathway than electrophilic substitution
reactions9.
28
,
Conventionally, bromination of aniline has been accomplished
using molecular bromine and metal halides10,11. Various
brominating reagents have been used as a brominating source
to achieve the bromination of aniline such as, N-
The sulfoxide and sulfone are two important intermediates in
organic synthesis. They are used for the construction of
biologically significant molecules38,39. They are also serve as
important intermediates for the synthesis of useful building
blocks in fine chemicals40. They are valuable synthetic
intermediates in agriculture41, pharmaceuticals42, and chemical
bromosuccinimide with acid catalyst12–14
,
1-butyl-3-
methylimidazolium tribromide under solvent-free conditions15,
Hydrobromic acid along with hydrogen peroxide16, hydrobromic
acid with DMSO17, Potassium bromide with hydrogen
peroxide18 and oxone19, etc. β-Cyclodextrin has also been used
industries43–45
.
Number of methods has been reported in the literature for the
selective oxidation of sulfide to sulfoxide and sulfone using
different oxidants, such as hydrogen peroxide46–50 as a key
oxidant, tertiary butyl hydroperoxide51–53, urea hydrogen
peroxide54,55, sodium perborate56, and sodium percarbonate56.
Institute of Chemical Technology, Department of Dyestuff Technology,
Nathalal Parikh Road, Matunga, Mumbai, Maharashtra, India.
E-mail: gsshankarling@gmail.com, gs.shankarling@gmail.com
This journal is © The Royal Society of Chemistry 20xx
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The oxidative abilities of above-mentioned oxidants are not regioselective bromination of aniline under thesVeiewcoAnrtidclietOionnlinse.
strong enough to oxidize various sulfides to sulfoxides and (Table 2). In the case of 50% hydrogen peroxide, a 45% yield of
DOI: 10.1039/C8NJ06038J
sulfones.57 Therefore, they are coupled with the metal catalysts, 2a was obtained (Table 2, entry 1). Moreover, Oxone, TBHP and
activators or promoters. Whereas another class of oxidants UHP offered 80%, 40%, 72% yields of 2a respectively (Table 2,
involves, use of peracids such as, meta-chloroper benzoic entries, 2, 3 & 4)). Thus, the achieved optimal reaction
acid58,59, peracetic acid60, performic acid in various organic conditions have been established for further studies of
solvents, though the above-mentioned peracids provide good bromination and iodination.
yields of sulfoxide and sulfones, but suffers from several
drawbacks such as less selectivity for desired products, require
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Table 1. Optimization of reaction conditions for bromination and
iodination of aniline
longer reaction time and stability of oxidant at high
temperature. The stability and shock-sensitive nature of the
oxidants is important aspects as it is the major concern in
oxidation reactions.
Here in we report regioselective mono-bromination and mono-
iodination of aniline at 50 to 52°C and temperature dependent
selective oxidation of sulfide to sulfoxide and sulfone using
environmentally benign 4Na2SO4.2H2O2.NaCl oxidant in acetic
acid at 50 and 75°C was performed respectively. The oxidant is
stable at room temperature and non-shock sensitive in nature.
The reported adduct is prepared from non-toxic, easily
available, inexpensive sodium sulfate, hydrogen peroxide, and
sodium chloride61. The hydrogen peroxide is embedded in the
cage62 and that might be responsible for the selective oxidation
of anilines and sulfides.
Oxid Tim
Isolated
Yieldb of
2a (%)
40
Tempo
C
Entry
Solvent
ant
equi.
1
1
1
1
e
(h)
8
8
3
1
2
3
4
Acetic acid
Acetic acid
Acetic acid
Acetic acid
30-32
45
50-52
60
75
89
50
5
5
Acetic acid
1
5
70
30
Result and discussion
6
7
8
Acetic acid
Acetic acid
Acetic acid
Ethanol
Methanol
Acetonitrile
DMF
Ethyl acetate
Dichloromet
hane
1
2
3
1
1
1
1
1
2.5
8
50-52
50-52
50-52
50-52
50-52
50-52
50-52
50-52
90c
85d
87e
NR
NR
NR
Traces
NR
In order to investigate the reactivity of the oxidant, Initially
aniline 1a was taken along with 4Na2SO4.2H2O2.NaCl adduct as
oxidant (1 equiv.) and potassium bromide (KBr) (1 equiv.) as
brominating source in acetic acid and stirred at room
temperature for 8h, only 40% yield of P-bromoaniline was
obtained. Further, to improve the Yield of the product 2a, model
reaction was carried out at different temperatures (Table 1).
We observed that temperature has pronounce effect of on the
yield of product 2a. As temperature increases to
50-52oC, the product yield increased subsequently in shorter
reaction time (Table 1, entries 2 & 3). At higher temperature
reaction mass turns blackish and multiple spots were observed aReaction condition:1a (1 equiv), 4Na2SO4-2H2O2-NaCl (1 equiv); solvent :3 mL; KBr
on TLC (Table 1, entries 4 & 5). Therefore, 50-52 °C was chosen
as the optimized reaction temperature for the oxidative
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1
1
10
10
50-52
50-52
NR
NR
Water
1 equiv.; bIsolated yield; cP-Iodoaniline; d2,4-dibromo aniline; e2,4,6-tribromo
aniline; NR: No reaction.
bromination. Further the model reaction was carried out in
Table 2. Reaction with other oxidizing agents for bromination of
various polar and non-polar solvents. Highest yield of product aniline
2a observed when the reaction was carried out in acetic acid.
But other solvents were failed to give the product 2a (Table 1,
bIsolate
d Yield
(%) of
2a
Oxidan
t
equiv.
Entr Oxidan
y
Temperatur Tim
entries, 9-15). We have also carried out the dibromination and
tribromination of aniline by taking 2 and 3 equivalents of
potassium bromide under these conditions and obtained good
yields of product 3 and 4 within 8h and 10h respectively (Table
1, entries, 7 & 8). Above Optimized reaction conditions were
also applied for the oxidative iodination of aniline, using
potassium iodide as an iodinating agent, where para-
iodoaniline was achieved with 90% yield exclusively within 2.5h
(Table 1, entry 6).
t
e
e
50 %
H2O2
Oxone
TBHP
UHP
1
1
50-52
5
45
2
3
4
1
1
1
50-52
50-52
50-52
5
5
5
80
40
72
aReaction condition:1a (1 equiv), Acetic acid: 3 mL; KBr 1 equiv.; bIsolated yield;
A comparative study with other commercially available oxidants
was performed to see the applicability of the current protocol.
All below-mentioned oxidants were failed to give the
Temperature: 50-52oC.
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Substrate scope for bromination of anilines:
ARTICLE
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DOI: 10.1039/C8NJ06038J
50-
With the optimized reaction conditions in hand, further we
examine the substrate scope of anilines. It was observed that
anilines bearing an electron-donating, electron withdrawing, or
halogen group were well tolerated (Table 3) providing good to
excellent yields of monobrominated products. Moreover,
Monobromination exclusively takes place at the para position
(Table 3, entries 1, 2, 3, 5, and 6, 9, 10). But when the para
position was blocked with a substituent, bromination occurs at
ortho position (Table 1, entries 4, 7, 8, and 11). Substitution at
2, 3 and 4 positions with methyl group gave 88, 84 and 87%
yields of product 2b, 2c, and 2d respectively (Table 3, entries, 2,
3 & 4). 2-chloroaniline and 2-methoxyaniline also afforded 86
and 85% yield of 2e and 2f respectively (Table 3, entries, 5 & 6).
Furthermore, 4-bromoaniline and 4-chloroaniline smoothly
underwent oxidative bromination and produced 91 and 88%
yield of desired products (2g and 2h) respectively (Table 3,
entries, 7 & 8). Reaction was also tried out with electron
withdrawing nitro group at 2, 3 and 4 positions, surprisingly,
reactions were proceeded efficiently and provided good to
excellent yields of product 2i, 2j, and 2k (Table 3, entries, 9, 10
and 11).
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50-
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87
50-
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Table 3. Substrate scope for oxidative bromination of aniline
aReaction conditions: 1 (1 equiv); Adduct: (1 equiv), Adduct: 4Na2SO4-2H2O2-NaCl
(1 equi); KBr: 1 equi.; Acetic acid: 3 mL; Temperature: 50-52o C.
Tim
e
(h)
Isolate
d Yield
(%)
Entr
y
Tem
p oC
Substrate
Product
Substrate scope for Iodination of Anilines:
Optimized reaction conditions were also applied for iodination
of substituted anilines (Table 1). Unsubstituted Aniline
selectively furnished 4-iodoaniline with 90% yield within 2h
(Table 4, entry 1). Whereas, Aniline bearing electron donating
substituents such as 2-CH3, 3-CH3 and 4-CH3 provided
comparatively lesser yields of desired products (Table 4, entries,
2, 3 & 4). Aniline having 2-Cl, 2-OCH3 groups smoothly
underwent oxidative iodination providing 89 and 87% yields of
product 3e and 3f respectively (Table 4, entries, 5 & 6). Aniline
bearing halogens such as 4-Br, 4-Cl, require more reaction time
as compared to 2-chloroaniline and offered 89% and 90% yield
of 3g and 3h respectively (Table 4, entries, 7 & 8). We have also
checked the effect of electron withdrawing group on the yield
of the reaction, aniline containing 2-NO2 and 4-NO2 provided 95
and 86% yields respectively (Table 4, entries, 9 & 10).
50-
52
1
3
90
50-
52
2
3
6.5
5
88
84
50-
52
50-
52
Above study shows that oxidative bromination requires more
reaction time as compared to oxidative iodination of aniline,
since the release of bromonium ion was quite slow as compared
to the iodinium ion.
4
6
87
Table 4. Substrate scope for oxidative iodination of aniline
50-
52
5
6
8
4
86
87
Temp Isolated
Time
Entry Substrate
Product
oC
Yield
(%)
(h)
50-
52
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aReaction conditions: 1 (1 equiv); Adduct: (1 equiv), Adduct: 4Na2SO4-2H2O2-NaCl
View Article Online
(1 equi); KI: 1 equi.; Acetic acid: 3 mL; Temperature: 50-52o C.
DOI: 10.1039/C8NJ06038J
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Figure 1. Plausible mechanism
Based on the above results and previous literature reports, a
tentative mechanism for the oxidative bromination was
proposed as shown in Figure 1. Initially acetic acid reacted with
the 4Na2SO4.2H2O2.NaCl adduct to generate peracetic acid in
situ. The peracetic acid generated in situ further reacts with
potassium bromide (KBr) and forms bromonium ion (Br+) and
potassium hydroxide (KOH). Then Bromonium ion reacts with
the various aromatic amines to form a variety of brominated
compounds
.
Oxidation of sulfide to sulfoxide and sulfone:
At the onset of our investigation for the oxidation of sulfides,
first, methyl phenyl sulfide was taken as a model substrate to
optimize the experimental conditions for sulfoxide synthesis.
Our primary investigation was started with adduct equivalent
study, which reveals that, sulfoxide formation requires 3 equiv.
of adduct at room temperature (Table 5, entries 1-3). Though
the reaction provides good yield and selectivity for sulfoxide at
room temperature but requires longer reaction time. The
reaction conditions were further optimized by varying the
temperature. Temperature study reveals that, at 50 0C,
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4
50-52 87
50-52 89
50-52 90
0
sulfoxide and at 75 C, sulfone formation was predominant.
Now, we can say that adduct is temperature dependent giving
selectivity for sulfoxide and sulfone at the same equivalent of
the adduct (Table 5, entries 4-7).
From the above results, we can conclude that selectivity of
adduct for the synthesis of sulfoxide and sulfone was
temperature dependent. (Table 5, entries 4-7). When reaction
performed in ethanol and water 30% and 60% yield of 5a was
observed respectively (Table 5, entries 10 & 11) while, 1, 2-
dichloromethane and acetonitrile resulted in much lower yields
(Table 5, entries 8 & 9). Acetic acid was found to be the most
favorable solvent for the sulfide oxidation reactions (Table 5,
entry 5).
6
4.5
Table 5. Optimization of reaction parameters for sulfide oxidation
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50-52 95
50-52 86
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Oxidant
b Yield
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Time
(%) of
(h)
Sr.no
Solvent
equivalent Temp
5a
75
50
14
4
88
85
1
Acetic acid
Acetic acid
Acetic acid
Acetic acid
Acetic acid
Acetic acid
Acetic acid
Acetonitrile
Dichloromethane
Ethanol
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3
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3
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30-32
30-32
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91c
traces
traces
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Water
50
60
aReaction conditions: 1a (1 mmol); Solvent: 3 ml; adduct: 4Na2SO4-2H2O2-NaCl;
Temperature: 30-32 to 75oC; bIsolated yield; cyield of 6a
Substrate scope for oxidation of sulfide to sulfoxide and sulfone:
The optimized reaction conditions were successfully applied for
the selective synthesis of sulfoxides and sulfones. Methyl
phenyl sulfide gave selectively 5a in 91% yield at room
temperature and 6a in 93% yield at 50 °C (Table 6, entry 1).
Diphenyl sulfide requires more reaction time for completion of
reaction due to the steric hindrance of the phenyl ring (Table 6,
entries 2). The substrate such as 2-(benzylthio) acetic acid,
Ethyl-2-benzylthio) acetate and 2-(benzylthio) ethanol
furnished good to excellent yield of corresponding sulfoxide and
sulfones (Table 6, entries 3-5). N-alkyl substituted derivatives
such as 4f gave 89 and 88% yield of 5f and 6f respectively (Table
6, entry 6). Interestingly, Sulfide-containing formyl group
provided excellent yields of desired products without over-
oxidation of formyl group (Table 6, entry 7). Number of Electron
donating and withdrawing substrates also reacted well under
these reaction conditions and provided a good yield of desired
sulfoxides and sulfones (Table 6, entries 8 & 9).
5.
50
75
50
4
5
7
84
85
89
6.
75
50
8
6
88
86
Table 6. Oxidation of sulfide to sulfoxide and sulfone
7.
Entr
y
Substrate
Product
Temp
Time
(h)
Yiel
db
(%)
91
1
50
2.5
10
10
75
7
84
75
50
93
87
2.
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solvents. The chemical shifts are expressed in parts per million
(ppm) and tetramethylsilane (TMS) was used as an internal
reference.
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DOI: 10.1039/C8NJ06038J
Procedure for oxidative bromination and iodination of Aniline:
In 50 ml Round bottom flask, aniline 1a (1.07 mmol) was added
to acetic acid (3mL) at room temperature. Then potassium
bromide/ potassium iodide (1.07 mmol) was added followed by
the stepwise addition of adduct (1.07 mmol) at room
temperature and stirred the reaction mass at 50-52oC for an
appropriate time. The progress of the reaction was monitored
by thin layer chromatography. After completion of the reaction,
the resulting reaction mixture was diluted with water,
quenched with sodium bicarbonate and then extracted with
ethyl acetate. The organic layers were washed with water and
dried over Na2SO4 and the solvent was concentrated under
vacuum. The residue was purified by column chromatography
using hexane: ethyl acetate as eluent.
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General procedure for the synthesis of sulfoxide and sulfone:
In 50 ml round bottom flask, methyl phenyl sulfide 4a (0.833
mmol) was added to acetic acid (3mL) then 4Na2SO4.2H2O2.NaCl
(3 equiv.) adduct was added slowly at room temperature, the
reaction mass was heated at 50oC for sulfoxide synthesis and at
75oC for sulfone synthesis. The reaction was monitored by thin
layer chromatography. After completion of the reaction, the
resulting reaction mixture was diluted with water, quenched
with sodium bicarbonate and then extracted with ethyl acetate.
The organic layer was washed with water and dried over
Na2SO4, and the solvent was concentrated under vacuum. The
residue was purified by column chromatography using hexane:
ethyl acetate as eluent.
aReaction conditions: 1 (1mmol, 1 equi.); Adduct: 4Na2SO4-2H2O2-NaCl (3 equi.);
Solvent: Acetic acid, 3 ml; bIsolated yield.
Conclusions
In conclusion, we have successfully demonstrated the various
applications of the adduct in organic synthesis. The
enclathrated adduct was found to be stable and provided
selective products at different temperatures. The oxidative
bromination and oxidative iodination showed excellent
regioselectivity at 50-52°C. In addition, the selective oxidation
of sulfide to sulfoxide and sulfone was also achieved providing
good to excellent yields of desired products. Substrates
comprising electron donating and withdrawing substituents
smoothly underwent oxidation. The clathrate like structure of
the adduct might be responsible for the selective oxidation at a
different temperature.
Spectral data
1. 4-bromoaniline63 (2a): White to light yellow solid; yield: 90%; mp
62-64°C; 1H NMR (400 MHz, CDCl3) δ 7.22 (d, J = 6.7 Hz, 2H), 6.55
(d, J = 6.7 Hz, 2H), 3.46 (s, 2H). 13C NMR (126 MHz, CDCl3) δ 145.40,
131.99, 116.71, 110.17.
2. 4-bromo-2-methylaniline64 (2b): off white solid; yield: 88%; mp
56-58°C; 1H NMR (400 MHz, CDCl 3) δ 7.14 (s, 1H), 7.10 (d, J = 7.7
Hz, 1H), 6.53 (d, J = 8.3 Hz, 1H), 3.01 (s, 2H), 2.12 (s, 4H).
3. 4-bromo-2-chloroaniline65 (2e): off white solid; yield: 86%; mp 70-
72°C; 1H NMR (400 MHz, CDCl3) δ 7.36 (s, 1H), 7.14 (d, J = 8.4 Hz,
1H), 6.62 (d, J = 8.4 Hz, 1H), 4.04 (s, 2H).
4. 2, 4-dibromoaniline66 (2g): white solid; yield: 91%; mp 78-80°C;
1H NMR (400 MHz, CDCl3) δ 7.51 (s, 1H), 7.18 (d, J = 8.3 Hz, 1H),
6.63 (d, J = 8.4 Hz, 1H), 4.08 (s, 2H).
There are no conflicts of interest to declare.
Acknowledgment
Authors are thankful to UGC-GREEN TECH and UGC-CAS for
providing financial assistance.
5.
2, 4, 6-tribromoaniline67 (4): Brown to whitish solid; yield: 87%;
mp 122-124°C; 1H NMR (400 MHz, CDCl3) δ 7.49 (s, 2H), 4.55 (s,
2H). 13C NMR (101 MHz, CDCl3) δ 176.62, 141.13, 133.70, 108.61.
Experimental
General
All the reagent grade chemicals were purchased from Sigma
Aldrich, SD fine, Alfa aesar, and were used as received. The
progress of the reactions was monitored using commercially
available Thin-Layer Chromatography (TLC) plates of silica gel 60
F-254. The synthesized products were characterized using
1HNMR. 1H NMR spectra were recorded on Agilent
spectrometer at 500 MHz using CDCl3-d and DMSO-d6 as
6. 4-bromo-2-nitroaniline64 (2i): orange solid; yield: 94%; mp 110-
112°C; 1H NMR (400 MHz, CDCl3) δ 8.24 (d, J = 1.9 Hz, 1H), 7.40 (dd,
J = 8.8, 1.9 Hz, 1H), 6.71 (d, J = 8.9 Hz, 1H), 6.11 (s, 2H).
7. 2-bromo-4-nitroaniline68 (2k): yellow solid; yield: 87%; mp 98-
100°C; 1H NMR (400 MHz, CDCl3) δ 8.36 (s, 1H), 8.02 (d, J = 8.2 Hz,
1H), 6.73 (d, J = 8.8 Hz, 1H), 4.82 (s, 2H). 13C NMR (126 MHz, CDCl3)
δ 149.60, 129.07, 124.84, 113.16, 106.97.
1
8. 4-iodoaniline69 (3a) : off white solid; yield: 90%; mp 60-62°C; H
NMR (400 MHz, CDCl3) δ 7.39 (d, J = 7.0 Hz, 2H), 6.46 (d, J = 6.9 Hz,
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2H), 3.79 – 3.44 (s, 2H). 13C NMR (126 MHz, CDCl3) δ 146.03,
137.89, 117.28, 79.38.
9. 4-iodo-2-methylaniline70 (3b) : off white solid; yield: 88%; mp 88-
90°C;
2H), 8.20 – 8.13 (m, 2H), 3.13 (s, 3H). 13C NMR (126 MHz, CDCl3) δ
View Article Online
150.85, 145.92, 128.97, 124.63, 44.44.
DOI: 10.1039/C8NJ06038J
1H NMR (400 MHz, CDCl3) δ 7.32 (s, 1H), 7.27 (d, J = 8.5 Hz, 1H),
6.43 (d, J = 8.0 Hz, 1H), 3.59 (s, 2H), 2.09 (s, 3H).
10. 2-iodo-4-methylaniline71 (3d): Orange crystalline solid; yield: 83%;
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Graphical Abstract
Sodium sulfate-Hydrogen peroxide-Sodium chloride adduct: Selective Protocol for,
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Oxidative bromination, iodination and temperature dependent oxidation of sulfide to
sulfoxide and sulfones
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Eknath M. Gayakwada, Khushbu P. Patela, and Ganapati S. Shankarlinga*
Sodium sulphate-Hydrogen peroxide-Sodium chloride adduct: Selective protocols for anilines and sulfides Oxidation
NH2
NH2
NH2
NH2
Br
4Na2SO4.2H2O2.NaCl
KI
KBr
I
S
O
S
O
S
Solvent- Acetic acid
O