Substrate-dependent order of catalytic activity for a series of Fe(III) and Mn(III) porphyrins in the oxidation of organic sulfides and olefins with periodate

Article abstract of DOI:10.1007/s13738-014-0549-9

The oxidation of organic sulfides and olefins with tetra-n-butylammonium periodate (TBAP) in the presence of Fe(III) and Mn(III) meso-tetraarylporphyrins bearing phenyl, 2-chlorophenyl, 4-chlorophenyl and 4-methoxyphenyl groups at the meso positions and i

Full text of DOI:10.1007/s13738-014-0549-9

J IRAN CHEM SOC (2015) 12:863–872
DOI 10.1007/s13738-014-0549-9
ORIGINAL PAPER
Substrate‑dependent order of catalytic activity for a series
of Fe(III) and Mn(III) porphyrins in the oxidation of organic
sulfides and olefins with periodate
Saeed Zakavi · Zohreh Kayhomayoon · Saeed Rayati
Received: 19 February 2014 / Accepted: 18 October 2014 / Published online: 8 November 2014
© Iranian Chemical Society 2014
Abstract The oxidation of organic sulfides and olefins
with tetra-n-butylammonium periodate (TBAP) in the pres-
ence of Fe(III) and Mn(III) meso-tetraarylporphyrins bear-
ing phenyl, 2-chlorophenyl, 4-chlorophenyl and 4-meth-
oxyphenyl groups at the meso positions and imidazole
(ImH) has been studied and compared. With the excep-
tion of the metalloporphyrins with 4-methoxyphenyl sub-
stituents, the oxidative stability of the iron porphyrins was
considerably greater than that of the manganese ones. The
stronger π–π interaction between the porphyrin core and
the iron center in comparison with the manganese center
was suggested to explain the higher oxidative stability of
the iron porphyrins. The metalloporphyrins with poor elec-
tron-donating substituents, i.e., 2-chlorophenyl and 4-chlo-
rophenyl often provided much lower catalytic activity com-
significantly higher catalytic activities compared to the
manganese counterparts in the oxidation of methyl phe-
nyl sulfide, the catalytic activities were comparable for the
oxidation of diallyl sulfide. On the other hand, the oxida-
tion of olefins with TBAP gave different order of catalytic
activities for the metalloporphyrins. However, the man-
ganese porphyrins were generally more efficient catalysts
compared to the iron one. Also, the iron or manganese
porphyrins with more electron-donating meso substituents
were found to be more efficient than the other ones. The
competitive oxidation of cis- and trans-stilbene provided
evidence for the participation of a high valent oxo metal
species and a six-coordinate periodato one as the active
oxidants, although in the case of MnT(2-Cl)PPOAc and
FeT(2-Cl)PPOAc the results are strongly in favor of a high
valent oxo metal species as the dominant active oxidant.
−
pared to the other catalysts. The departure of IO3 , leading
to the formation of high valent oxo metal species, seems to
be facilitated by the presence of strong electron-donating
groups at the meso positions. In this catalytic system, the
sulfoxide/sulfone molar ratio is determined by stereoelec-
tronic properties of the substituents attached to the sulfur
atom of the organic sulfide and the meso-aryl groups of the
metalloporphyrins. Although the iron porphyrins showed
Keywords Iron(III) porphyrins · Manganese(III)
porphyrins · Oxidation · Sulfide · Sulfoxide · Sulfone ·
Olefins · Epoxide
Introduction
Due to the importance of sulfoxides as synthetic interme-
diates in organic syntheses, selective oxidation of sulfides
to sulfoxide generated much excitement and interest for
various synthetic purposes and applications [1–6]. In this
regard, metalloporphyrins as chemical models of the active
site of cytochrome P-450 enzymes hold an important posi-
tion in the catalysis of oxidative reactions [5, 7]. Different
strategies may be used to prevent further oxidation of sul-
foxide to sulfone in oxidation of sulfides [3]. The use of
urea adduct of hydrogen peroxide (UHP) instead of 30 %
aqueous hydrogen peroxide was found to result in highly
Electronic supplementary material The online version of this
article (doi:10.1007/s13738-014-0549-9) contains supplementary
material, which is available to authorized users.
S. Zakavi (*) · Z. Kayhomayoon
Department of Chemistry, Institute for Advanced Studies in Basic
Sciences (IASBS), Zanjan 45137-66731, Iran
e-mail: zakavi@iasbs.ac.ir
S. Rayati
Department of Chemistry, K.N. Toosi University of Technology,
P.O. Box 16315-1618, Tehran 15418, Iran
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J IRAN CHEM SOC (2015) 12:863–872
Fig. 1 Iron (III) and Mn (III)
porphyrins used in this study
OAc
Ar
N
N
Ar
M
Ar
N
N
2
3
Ar
1
4
M = Fe(III) or Mn(III)
Ar
Metalloporphyrin
Porphyrin
Phenyl
FeTPPOAc or MnTPPOAc
H2TPP
2-chlorophenyl
4-chlorophenyl
4-methoxyphenyl
FeT(2-Cl)PPOAc or MnT(2-Cl)PPOAc
FeT(4-Cl)PPOAc or MnT(4-Cl)PPOAc
H2T(2-Cl)PP
H2T(4-Cl)PP
H2T(4-OMe)PP
FeT(4-OMe)PPOAc or MnT(4-OMe)PPOAc
chemoselective oxidation of sulfide to sulfoxide on Ti-beta
zeolite [8]. Controlled release of H2O2 and the anhydrous
nature of the oxidant were suggested to be the main advan-
tages of UHP. Also, oxidation of sulfides with Br2 on wet
silica gel gives the corresponding sulfoxide as the sole
product [9]. On the other hand, in a reaction catalyzed by
metalloporphyrins, the use of protic solvents was found to
facilitate the formation of high valent metal-oxo porphyrin
species [10, 11]. The removal of water from the reaction
mixture by using water-free oxidants such as polymer-
supported hydrogen peroxide has been also shown to favor
the formation of sulfoxide as the major product in the oxi-
dation reaction of sulfides with hydrogen peroxide cata-
lyzed by Mn (TPP) (OAc) [12]. Recently, chemoselective
oxidation of sulfides to the corresponding sulfoxides with
trans-dioxoruthenium (VI) porphyrins has been reported
[13]. Also, oxidation of sulfides with different terminal oxi-
dants in the presence of electron-rich and electron-deficient
metalloporphyrins has been studied [14–20]. However,
little attention has been given to the influence of the type
of metal center and the meso substituents on the catalytic
activity and product selectivity of metalloporphyrins in the
oxidation of sulfides with terminal oxidants. The study of
the effect of stereoelectronic properties of the meso and/or
β substituents of metalloporphyrins on their catalytic activ-
ity for the oxidation of olefins has been the subject of sev-
eral studies over the past two decades [19, 21–28]. In the
present work, the catalytic activity of a series of manganese
and iron porphyrins (Fig. 1) in the oxidation of sulfides and
olefins with tetra-n-butylammonium periodate (TBAP) has
been studied and compared. To our knowledge, it is the first
report on the use of periodate as the oxidant for the iron and
manganese porphyrin-catalyzed oxidation of sulfides under
homogeneous conditions. The aim of this study is to inves-
tigate the influence of stereoelectronic effects of the meso
substituents and the nature of metal center on the product
distribution as well as the order of catalytic activity of a
series of metalloporphyrins for the oxidation of sulfides and
olefins with TBAP as a relatively weak oxidant. The results
provide evidence for the substrate-dependent order of cata-
lytic activity of different iron(III) and manganese(III) por-
phyrins in the oxidation of these compounds.
Experimental
Instrumental
All reactions were analyzed by a Varian-3800 gas chro-
matograph equipped with an HP-5 capillary column
(phenylmethyl siloxane 30 m × 320 µm × 0.25 µm)
or a packed column (Chromosorb WHP 80–100 Mesh,
1
4 mm × ¼ × 2 m) and a flame-ionization detector. H
NMR spectra were obtained on a Bruker Avance DPX-
400 MHz spectrometer. The absorption spectra were
recorded on a Pharmacia Biotech Ultrospec 4000 UV–Vis
spectrophotometer.
Preparation of the porphyrins and metalloporphyrins
H2TPP, H2T(4-OCH3)PP, H2T(2-Cl)PP, H2T(4-Cl)PP [29,
30] and the corresponding manganese and iron complexes
[31–33] were prepared and purified according to the litera-
1
ture. H NMR (400 MHz CDCl3, TMS) (δ ppm): H2TPP:
−2.78 (2H, s, NH); 7.75–7.77 (12H, m, Hm,p); 8.25-8.30
(8H, dd, Ho); 8.90 (8H, s, Hβ); H2T(4‑OMe)PP: −2.76
(2H, s, NH); 4.15 (12H, s, CH3); 7.29–7.33 (8H, dd, Hm);
8.14–8.18 (8H, dd, Ho); 8.86 (8H, s, Hβ); H2T(2‑Cl)PP:
−2.66 (2H, s, NH); 7.63–7.70 (4H, m); 7.75–7.83 (4H, qt);
7.85–7.90 (4H, m); 8.10–8.30 (4H, m); 8.76 (8H, s, Hβ)
(Non-well resolved signals are probably due to the pres-
ence of atropisomers [34]. H2T(4‑Cl)PP: −2.85 (2H, s,
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J IRAN CHEM SOC (2015) 12:863–872
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Table 1 Degradation of the manganese and iron porphyrins under the reaction conditions
Iron porphyrins
Degradationa, b (%)
Manganese porphyrins
Degradationa (%)
FeTPPOAc
13.3
41.9
12.1
9.7
MnTPPOAc
80.0
44.0
71.5
100.0
FeT(4-OCH3)PPOAc
FeT(2-Cl)PPOAc
FeT(4-Cl)PPOAc
MnT(4-OCH3)PPOAc
MnT(2-Cl)PPOAc
MnT(4-Cl)PPOAc
The optimized molar ratios of catalyst:ImH:methyl phenyl sulfide:TBAP are 1:15:85:170 and 1:5:85:170 for the reaction catalyzed by the man-
ganese and iron porphyrins, respectively
a
On the basis of the absorbance changes (ΔA) at the λmax of the iron porphyrins (ΔA/A)
b
For a reaction time of 4 h
NH); 7.77–7.80 (8H, d, Hm); 8.15–8.20 (8H, d, Ho); 8.89
(8H, s, Hβ). The absorption bands of FeTPP(OAc), FeT(4‑
OCH3)PP(OAc), FeT(2‑Cl)P(OAc), FeT(4‑Cl)P(OAc),
MnTPP(OAc), MnT(4‑OCH3)PP(OAc), MnT(2‑Cl)
P(OAc) and MnT(4‑Cl)P(OAc) in CH2Cl2, appear at [λmax
(logε): 380 (4.39), 418 (4.59), 510 (3.79), 579 (3.48), 655
(3.41), 694 (3.44)], [421 (4.34), 514 (3.93), 576 (3.75), 617
(3.64), 704 (3.5)], [378 (4.33), 416 (4.63), 510 (3.84), 580
(3.58), 651 (3.50), 686 (3.46)], [380 (4.40), 417 (4.67), 511
(3.84), 573 (3.65), 663 (3.5), 692 (3.5)], [339 (4.16), 368
(4.27), 395 (4.20), 476 (4.53), 531 (2.57), 582 (3.69), 619
(3.71)], [348 (4.30), 377 (4.38), 404 (4.29), 478 (4.65), 529
(3.62), 584 (3.75), 620 (3.79)], [349 (4.39), 372 (4.46), 400
(4.31), 477 (4.74), 529 (3.67), 581 (3.83), 612 (3.69)], [338
(4.27), 369 (4.39), 393 (4.32), 476 (4.67), 529 (3.63), 582
(3.76), 619 (3.77)] nm, respectively (for more experimental
details see the supporting information of [28] ).
Degradation of metalloporphyrins
The extent of degradation of metalloporphyrins in the pres-
ence of methyl phenyl sulfide (or cyclohexene, see 3.3.2)
for a reaction time of 4 h was measured on the basis of the
absorbance changes (ΔA) at the λmax of the metalloporphy-
rins (ΔA/A). The general procedure and the molar ratios are
as mentioned above (see [27, 28] for more details).
Results and discussion
The catalytic performance of transition metal-based cata-
lysts is influenced by different factors such as the Lewis
acid strength of the metal center, the accessibility of vari-
ous oxidation states and accommodation of various coor-
dination numbers [35]. In the case of metalloporphyrins,
the oxidative stability of the complexes is one of the main
parameters affecting their catalytic efficiency under oxida-
tive conditions [7, 36].
General oxidation procedure
Stock solutions of the metalloporphyrins (0.003 M)
and ImH (0.5 M) were prepared in CH2Cl2. In a typi-
cal reaction, sulfide or olefin (0.25 mmol), Mn-porphyrin
(0.003 mmol, 1 ml) and ImH (0.015 or 0.03 mmol, 30 or
60 μl, see the text) were added into a 10 ml round bottom
flask containing 1 ml of CH2Cl2. Then, 0.5 mmol (0.217 g)
TBAP was added. The mixture was stirred thoroughly for
4 h at ambient temperature. After the required time, 5 ml of
diethyl ether was added to the flask and the reaction mix-
ture passed through a short silica gel column to remove the
unreacted TBAP and any remaining metalloporphyrin. Low
solubility of TBAP in ether led to the precipitation of unre-
acted oxidant following the addition of ether to the reaction
mixture. Also, the used metalloporphyrins are slightly solu-
ble in ether and were separated by chromatography through
a short silica gel column. The resulting solution was ana-
Oxidative stability of the metalloporphyrins in the presence
of methyl phenyl sulfide
The stability of the catalysts toward oxidative degrada-
tion, studied under the optimized reaction conditions for
the oxidation of methyl phenyl sulfide with TBAP, was
found to decrease in the order FeT(4-Cl)PPOAc≥FeT(2-
Cl)PPOAc≥FeTPPOAc>>FeT(4-OCH3)PPOAc≥MnT(4-
OCH3)PPOAc>>MnT(2-Cl)PPOAc>MnTPPOAc>MnT(4-
Cl)PPOAc (Table 1). The iron porphyrins exhibit higher
stability than the manganese ones. The carbon atoms with
the highest electron densities, i.e., the α and meso ones are
expected to be involved in oxidative degradation of metal-
loporphyrins [37]; according to the four-orbital model of
porphyrin spectra, the electron densities of the a1u and a2u
orbitals are largest on the α and meso positions, respec-
tively [38, 39]. Although in Sanderson’s electronegativity
scale, Fe(III) and Mn(III) are of the same electronegativity,
1
lyzed by GLC. H NMR was used to analyze the products
in the case of cis- and trans-stilbene. All reactions were
repeated at least three times, analyzed by GC and averaged.
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Table 2 Oxidation of methyl phenyl sulfide with TBAP in dichloromethane in the presence of different metalloporphyrins
Metalloporphyrins
Conversiona, b (%)
Sulfoxide (%)
Sulfone (%)
Sulfoxide/sulfone molar ratio
MnTPPOAc
52.5
57.1
9.5
24.9
25.5
1.8
27.6
31.6
7.7
0.9
0.8
0.2
0.8
2.5
0.9
6.2
2.4
MnT(4-OCH3)PPOAc
MnT(2-Cl)PPOAc
MnT(4-Cl)PPOAc
FeTPPOAc
46.4
76.8
100.0
2.9
20.3
54.7
48.1
2.5
26.1
22.1
51.9
0.4
FeT(4-OCH3)PPOAc
FeT(2-Cl)PPOAc
FeT(4-Cl)PPOAc
1.7
1.2
0.5
See the footnotes of Table 1
No reaction was observed in the absence of catalyst (see also Table 3, for reaction catalyzed by the last two catalysts)
a
Analyzed by GC
b
Average of three runs
the higher stability of the iron porphyrins compared to that
of the manganese porphyrins provides indirect evidence for
the larger electron density on the α and/or meso positions
of the latter [40]. The coordination number of six leads to
a very similar effective ionic radius (78.5 pm) for high spin
manganese(III) and iron(III) cations [40]. In the first transi-
tion metal series, the increase in atomic number is associ-
ated with a decrease in energy of different orbitals, which
is more pronounced for 3d orbital than s and p ones. In the
metalloporphyrins, the decrease in energy of the 3d orbital
from the Mn(III) to Fe(III) seems to lead to a decrease in
the energy gap between the d orbitals of the latter and the
HOMOs of the porphyrin ligand [41]. This in turn would
lead to stronger interactions [42] between the π orbitals of
the porphyrin ligand as the electron donor and 3d orbitals of
Fe(III) as the electron acceptor. In other words, the iron(III)
cation seems to be a more effective electron acceptor com-
pared to the manganese(III) one. However, the iron and
manganese complexes of H2T(4-OCH3)PP were found to be
of similar stability. Apparently, the presence of the –OCH3
group as a strong π electron donor group [43] at the phe-
nyl substituents of H2T(4-OCH3)PP led to similar electron
density values on the α and meso carbons of the iron and
manganese complexes of this porphyrin. Interestingly, in the
series of iron porphyrin, FeTPPOAc was almost as stable
as FeT(2-Cl)PPOAc and FeT(4-Cl)PPOAc. The presence
of the bulky chlorine atom attached to the ortho position
of the meso-phenyl substituents was expected to cause an
increase in the stability of the FeT(2-Cl)PPOAc and MnT(2-
Cl)PPOAc relative to that of the corresponding complexes
with 4-Cl-phenyl substituents [44]. However, in spite of the
greater oxidative stability of MnT(2-Cl)PPOAc compared
to that of MnT(4-Cl)PPOAc, FeT(2-Cl)PPOAc and FeT(4-
Cl)PPOAc demonstrate the same stability. Also, there are
greater differences between the stability of the manganese
porphyrins compared to the iron complexes. Although
FeT(4-OCH3)PPOAc with the strongest electron-donating
groups at the meso positions showed the highest degree
of degradation among the used iron porphyrins, it seems
that the stability of the iron porphyrins is not significantly
dependent on the stereoelectronic properties of the meso
substituents [27, 28]. It is noteworthy that in the oxidation
of olefins with TBAP in the presence of these catalysts,
again MnT(2-Cl)PP(OAc) showed an unusually low sta-
bility compared to the other metalloporphyrins (see 3.3.2).
Also, these observations seem to be due to the involve-
ment of different mechanisms of catalyst degradation for
the used metalloporphyrins. The oxidative degradation of
metalloporphyrins may occur by an intermolecular or intra-
molecular mechanism [45]. The steric hindrance due to the
presence of bulky (2-Cl) phenyl at the meso positions can
prevent the catalyst degradation performed through an inter-
molecular mechanism. Accordingly, the weak influence of
the steric effects of (2-Cl) phenyl groups may be evident for
the involvement of an intramolecular mechanism of catalyst
degradation in the case of MnT(2-Cl)PPOAc and FeT(2-
Cl)PPOAc. Also, the participation of two different mecha-
nisms of catalyst degradation may explain the observed
order of oxidative stability for the metalloporphyrins.
Oxidation of sulfides
Oxidation of organic sulfides with TBAP gave the corre-
sponding sulfoxide and sulfone in different molar ratios. As
was reported in our previous work [19], running the reac-
tions in the absence of metalloporphyrin resulted in almost
no product.
Oxidation of methyl phenyl sulfide
Oxidation of methyl phenyl sulfide with TBAP
catalyzed by the manganese and iron porphyrins
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Table 3 Oxidation of
Metalloporphyrins
Conversiona, b(%) Sulfoxide (%) Sulfone (%) Sulfoxide/sulfone molar ratio
diallyl sulfide with TBAP in
dichloromethane in the presence
of different metalloporphyrins
MnTPPOAc
26.6
7.5
17.3
0.5
19.1
26.6
0.7
0.4
0.6
0.7
0.3
0.7
0.1
–
MnT(4-OCH3)PPOAc 43.9
MnT(2-Cl)PPOAc
MnT(4-Cl)PPOAc
FeTPPOAc
1.2
20.3
40.0
25.5
Trace
Trace
5.2
15.1
24.0
23.7
Trace
Trace
16.0
1.8
FeT(4-OCH3)PPOAc
FeT(2-Cl)PPOAc
FeT(4-Cl)PPOAc
Trace
Trace
a, b
See the footnotes of
–
Tables 1 and 2
afforded the corresponding sulfoxide and sulfone
in different molar ratios (Table 2). The efficiency
of manganese porphyrins decreases in the order
M n T ( 4 - O C H 3 ) P P OA c ≥ M n T P P OA c > M n T ( 4 -
Cl)PPOAc>>MnT(2-Cl)PPOAc. Also, the following
order of catalytic activity was observed for the iron por-
Oxidation of diallyl sulfide
In the oxidation of diallyl sulfide (Table 3), the catalytic
activity of the manganese porphyrins decreased as MnT(4-
OCH3)PPOAc>MnTPPOAc>MnT(4-Cl)PPOAc>>MnT(2-
Cl)PPOAc. As was observed for the oxidation of methyl
phenyl sulfide (Table 2), MnT(2-Cl)PPOAc presented
little or no catalytic activity. However, there was a large
difference between the catalytic performance of MnT(4-
OCH3)PPOAc and MnTPPOAc. Oxidation of diallyl
sulfide in the presence of the iron porphyrins resulted in the
following pattern of catalytic activity: FeTPPOAc>FeT(4-
OCH3)PPOAc>>FeT(4-Cl)PPOAc~FeT(2-Cl)PPOAc.
The order of catalytic activity of FeTPPOAc and FeT(4-
OCH3)PPOAc is in contrast to that observed in the oxida-
tion of diallyl sulfide. Also, the molar ratio of sulfoxide to
sulfone in the presence of a given catalyst is different from
that observed in the oxidation of methyl phenyl sulfide.
Comparison of the used metalloporphyrins shows that
here a manganese porphyrin, i.e., MnT(4-OCH3)PPOAc,
is the best catalyst of the series. According to the observed
order of catalytic activity for the used complexes, i.e.,
MnT(4-OCH3)PPOAc≥FeTPPOAc>MnTPPOAc~-
FeT(4-OCH3)PPOAc>MnT(4-Cl)PPOAc>>MnT(2-
Cl)PPOAc~FeT(2-Cl)PPOAc~FeT(4-Cl)PPOAc, the man-
ganese and iron porphyrins with more electron-donating
aryl substituents show comparable and higher catalytic per-
formance compared to the other metalloporphyrins.
The very low catalytic activity of FeT(2-Cl)PPOAc and
MnT(2-Cl)PPOAc in the oxidation of sulfides with TBAP
is unusual and seems to be due to the steric hindrance of
the ortho substituted meso-phenyl groups; the substitu-
tion of bulky and electron-withdrawing groups at the ortho
position of meso-tetra(aryl)porphyrins is among the main
strategies used to enhance the stability of these catalysts
under oxidative conditions [36, 44]. Due to the large size
of the sulfur atom of organic sulfides, a steric hindrance
between the aryl groups of the metalloporphyrin and the
aryl or alkyl substituents of the substrates may be consid-
ered as the possible cause of the unusually decreased cata-
lytic activity of FeT(2-Cl)PPOAc and MnT(2-Cl)PPOAc.
phyrins:
FeT(4-OCH3)PPOAc>FeTPPOAc>>FeT(2-
Cl)PPOAc~FeT(4-Cl)PPOAc. The manganese and iron
porphyrins with more electron-donating substituents
showed better catalytic activity compared to the electron-
deficient ones. Interestingly, FeT(2-Cl)PPOAc showed
very low catalytic activity. In spite of the lower oxidative
stability of FeT(4-OCH3)PPOAc relative to FeTPPOAc
(Table 1), the latter is significantly more efficient than the
former. On the other hand, the catalytic performance of
MnT(4-OCH3)PPOAc is comparable with that of MnTP-
POAc and MnT(4-Cl)PPOAc, although the oxidative deg-
radation of MnTPPOAc and MnT(4-Cl)PPOAc is ca. two
times larger than that of MnT(4-OCH3)PPOAc. The molar
ratio of sulfoxide/sulfone was also found to be different for
the used metalloporphyrins (Table 2). For the manganese
porphyrins, with the exception of MnT(2-Cl)PPOAc, the
oxidation reaction gave approximately equal amounts of
the sulfoxide and sulfone. In the reaction catalyzed by the
iron porphyrins, only FeT(4-OCH3)PPOAc and FeTPPOAc
displayed good catalytic activity and the other ones pro-
vided only very low catalytic activity. The highest conver-
sion of methyl phenyl sulfide to the oxidized products was
100 % obtained in the presence of FeT(4-OCH3)PPOAc.
Also, the use of FeTPPOAc led to the efficient oxidation
of methyl phenyl sulfide with good selectivity toward the
sulfoxide formation. The overall order of the catalytic
activity is: FeT(4-OCH3)PPOAc>FeTPPOAc>MnT(4-
O C H 3 ) P P O A c ≥ M n T P P O A c > M n T ( 4 -
C l ) P P OA c > > M n T ( 2 - C l ) P P OA c > > F e T ( 2 - C l ) -
PPOAc~FeT(4-Cl)PPOAc.
Accordingly,
the
iron
porphyrins with good electron donor groups at the meso
positions are more effective catalysts than the correspond-
ing manganese porphyrins, but in the case of the metal-
loporphyrins with (4-Cl) phenyl or (2-Cl) phenyl substitu-
ents, the latter are more efficient than the former.
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The higher reactivity of methyl phenyl sulfide than dial-
Cyclooctene:
MnT(4-OCH3)PP(OAc)>MnT(4-Cl)PP
lyl sulfide seems to be due to the lower steric hindrance of
the methyl group relative to that of the allyl substituents.
Also, the possible π electron donation from the phenyl sub-
stituents to the d orbitals of the sulfur atom may also be
involved.
In spite of the absence of close correlation between the
catalytic efficiency of the metalloporphyrins and the stereo-
electronic properties of the meso substituents (see 3.3.1),
the metalloporphyrins with weaker electron-donating and
more bulky groups at the meso positions are found to show
lower catalytic activity.
( O A c ) > M n T P P ( O A c ) > M n T ( 2 - C l )
PP(OAc)>FeTPP(OAc)≥FeT(4-Cl)PP(OAc)>FeT(4-
OCH3)PP(OAc)>FeT(2-Cl)PP(OAc).
cis-Cyclooctene:
MnT(4-OCH3)PP(OAc)>MnT(4-
C l ) P P ( O A c ) > M n T P P ( O A c ) > M n T ( 2 - C l )
PP(OAc)>FeTPP(OAc)>FeT(4-Cl)PP(OAc)>FeT(4-
OCH3)PP(OAc)>FeT(2-Cl)PP(OAc).
The manganese porphyrins were generally more efficient
catalysts than the iron analogs. However, with the excep-
tion of FeT(4-OCH3)PP(OAc) and FeT(2-Cl)PP(OAc) the
order of catalytic activity of the other metalloporphyrins is
found to change from one olefin to another. The introduc-
tion of good electron donor groups at the meso positions
increases the electron density at the metal center and con-
sequently decreases the Lewis acid strength of the metal
atom. Although the decreased Lewis acidity of the metal
center is expected to decrease its catalytic activity [35], the
increased electron density of the metal center would facili-
tate the formation of a high valent oxo metal species; the
coordination of periodate to Mn(III) or Fe(III) results in
the periodato six coordinate species as the active oxidant.
Oxidation of olefins
Oxidation of olefins with TBAP in the presence of the man-
ganese and iron porphyrins led to the formation of the cor-
responding epoxides as the sole product. However, a wide
range of olefins were used to investigate the relationship
between the steroelectronic properties of the meso sub-
stituents of the metalloporphyrins and their catalytic per-
formance. It should be noted that as previously reported
[19, 24, 27, 28], little or no reaction was observed in the
absence of the catalyst.
−
However, the departure of the leaving group (IO3 ) leads
to the formation of high valent oxo metal species. Accord-
ingly, the presence of strong electron-donating groups such
as –OCH3 favors the formation of a high valent oxo metal
intermediate as a stronger oxidizing agent compared to the
periodato intermediate. On the other hand, the presence
of good electron donors such as –OCH3 may enhance the
reactivity of catalyst precursor toward the oxidative degra-
dation. Higher catalytic activity of the metalloporphyrins
with better electron-donating groups shows that the for-
mer effect of –OCH3 is more important than the latter. The
introduction of bulky groups at the meso positions prevent
the effective overlap between the π systems of the aryl
groups and the porphyrin core and is expected to increase
the Lewis acid strength of the metal center. According to
the above discussion, this effect will increase the catalytic
activity of the metal center. However, the steric hindrance
caused by the bulky meso groups may decrease the cata-
lytic activity of the metalloporphyrin. In this condition, a
six-coordinate periodato species rather than a high valent
oxo metal one seems to be the dominant oxidizing agent.
The relative catalytic activity of the used metalloporphyrins
may be also be influenced by the mechanism of the oxida-
tion reaction performed by the active oxidants. According
to the literature [46], in oxidation of olefins catalyzed by
metalloporphyrins, different intermediates may be formed
by the reaction of active oxidants with the olefin; [2 + 2]
cycloaddition, 1-electron oxidation (with the formation
of a π cation radical species), electrophilic oxidation and
1-electron oxidation of olefin (with the formation of a radi-
cal species) as well as the concerted oxene insertion are
Oxidation of different olefins
The order of catalytic activity of the used metallopor-
phyrins for the oxidation of different olefins is as follows
(Tables S1–S8):
Styrene: MnT(4-OCH3)PP(OAc)≈MnT(4-Cl)PP(OAc)>
MnTPP(OAc)>MnT(2-Cl)PP(OAc)>FeTPP(OAc)>FeT(4-
Cl)PP(OAc)>FeT(4-OCH3)PP(OAc)>FeT(2-Cl)PP(OAc).
4-Methylstyrene: MnT(4-Cl)PP(OAc)>MnTPP(OAc)≈
M n T ( 4 - O C H 3 ) P P ( O A c ) > M n T ( 2 - C l )
PP(OAc)>FeTPP(OAc)>FeT(4-Cl)PP(OAc)>FeT(4-OCH3)
PP(OAc)>FeT(2-Cl)PP(OAc).
α-Methylstyrene: MnT(4-Cl)PP(OAc)≥MnT(4-OCH3)
P P ( O A c ) > M n T P P ( O A c ) ≈ M n T ( 2 - C l )
PP(OAc)>FeTPP(OAc)>>FeT(4-Cl)PP(OAc)>FeT(4-
OCH3)PP(OAc)>FeT(2-Cl)PP(OAc).
4-Methoxystyrene:
MnT(4-OCH3)PP(OAc)>MnTPP
( O A c ) > M n T ( 4 - C l ) P P ( O A c ) > M n T ( 2 - C l )
PP(OAc)>FeTPP(OAc)>FeT(4-Cl)PP(OAc)>FeT(4-
OCH3)PP(OAc)>FeT(2-Cl)PP(OAc).
Indene: MnT(4-OCH3)PP(OAc)>MnT(4-Cl)PP(OAc)>
MnTPP(OAc)>>MnT(2-Cl)PP(OAc)
FeTPP(OAc)>>
FeT(4-Cl)PP(OAc)>FeT(4-OCH3)PP(OAc)>FeT(2-Cl)
PP(OAc).
Cyclohexene:
MnTPP(OAc)>>MnT(4-Cl)PP(OAc)>
MnT(4-OCH3)PP(OAc)>MnT(2-Cl)PP(OAc)≥FeT(4-Cl)
PP(OAc)>FeTPP(OAc)>>FeT(4-OCH3)PP(OAc)>FeT(2-
Cl)PP(OAc).
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J IRAN CHEM SOC (2015) 12:863–872
869
1.5
1.0
0.5
0.0
Fig. 2 UV–Vis monitoring
of the degradation of MnT(4-
OCH3)PPOAc (left) and
FeT(4-OCH3)PPOAc (right) in
a dichloromethane solution con-
taining the catalyst, TBAP, ImH
and cyclohexene after a reaction
time of 4 h (see the footnotes of
Table 1 for the molar ratios)
↓
↓
2.0
1.0
0.0
325
400
475
550
625
700
325
400
475
550
625
λ (nm)
λ (nm)
the main mechanisms proposed for the reaction of a high
valent oxo metal species with olefins. Due to the different
stability of the carbocation, radical and π cation radicals of
the olefins, different mechanisms may be involved in the
oxidation of different olefins with the active oxidants.
ortho-substituents on the phenyl groups of meso-tetrap-
henylporphyrins [23, 24, 27, 28, 47, 48]. In this condition,
the involvement of a high valent oxo metal species would
lead to a value of ca. 1 for the molar ratio of cis- to trans-
stilbene oxide in the products. The exclusive participation
of a periodato complex as the active oxidant, the simultane-
ous participation of a high valent oxo metal species and a
periodato complex as the active oxidant are evident by the
observation of higher ratios of cis- to trans-stilbene oxide.
On the other hand, oxidation of cis-stilbene catalyzed by
metalloporphyrins with non-bulky substituents at the ortho
position is usually accompanied by partial cis to trans
isomerization of the product. Therefore, the results of com-
petitive oxidation reactions were corrected by the use of
control reaction performed with cis-stilbene (Table 4). The
results are in favor of the coexistence of a high valent oxo
metal species and a six-coordinate periodato one, i.e., (Por-
phyrin) M(III) (ImH) (IO4) as the reactive intermediates
responsible for oxygen atom transfer. However, the values
of 3.4 and 3.5 for the competitive reaction performed in the
presence of MnT(2-Cl)PPOAc and FeT(2-Cl)PPOAc sug-
gest the involvement of a high valent oxo manganese or
oxo iron species as the main active oxidant. It should be
noted that the introduction of groups as bulky as methyl
group at the ortho position was found to give a value of
ca. 3.5 rather than 1 for the molar ratio of cis- to trans-stil-
bene oxide, due to the steric hindrance around the reaction
center caused by the bulky groups [24].
Oxidative stability of the metalloporphyrins in the presence
of cyclohexene
Oxidation of styrene with TBAP gave the following
order of oxidative stability (Table S9) for the catalysts:
FeT(2-Cl)PP(OAc)>FeT(4-Cl)PP(OAc)>FeTPP(OAc)-
≥ M n T ( 4 - O C H 3 ) P P ( O A c ) > F e T ( 4 - O C H 3 )
PP(OAc)>MnTPP(OAc)>MnT(4-Cl)PP(OAc)≥MnT(2-
Cl)PP(OAc). Accordingly, the iron porphyrins are usually
more stable than the manganese ones. Also, while FeT(2-
Cl)PP(OAc) is the most stable catalyst of the series, the
manganese analog demonstrates the highest degree of
oxidative degradation. Taking into consideration the order
observed in the oxidation of methyl phenyl sulfide, the
oxidative stability of a series of metalloporphyrins is sug-
gested to depend on the type of substrate to be oxidized as
well as other factors such as the stereoelectronic properties
of the substituents at the periphery of the metalloporphy-
rins. Indeed, catalyst degradation is the result of a competi-
tive reaction between the organic compound and the cata-
lyst precursor for the active oxidants. Figure 2 shows the
change in the UV–vis spectrum of MnT(4-OCH3)PPOAc
and FeT(4-OCH3)PPOAc in a dichloromethane solution
containing the catalyst, TBAP, ImH and cyclohexene after
a reaction time of 4 h.
Conclusions
Indirect evidence for the nature of active oxidant
In conclusion, the oxidation of organic sulfides with
TBAP in the presence of different iron and manganese
meso-tetraarylporphyrins (aryl = phenyl, 4-methoxy-
phenyl, 4-chlorophenyl and 2-chlorophenyl) was studied
and the following results were obtained: (i) the electron-
deficient metalloporphyrins often presented much lower
Competitive oxidation of cis- and trans-stilbene has
been widely used to provide indirect evidence on the
nature of active oxidant in the metalloporphyrin-cata-
lyzed epoxidation of olefins in the absence of non-bulky
1 3

870
J IRAN CHEM SOC (2015) 12:863–872
Cis/trans epoxide (corrected)c
Table 4 Competitive oxidation of cis- and trans-stilbene in the presence of the mtalloporphyrins
Metalloporphyrins
Cis/trans epoxidea
Cis–trans isomerizationb (%)
MnTPPOAc
3.7
4.5
3.0
4.3
5.0
2.4
2.9
3.1
12.3
13.0
3.2
4.5
5.4
3.4
5.1
5.6
2.6
3.5
3.4
MnT(4-OCH3)PPOAc
MnT(2-Cl)PPOAc
MnT(4-Cl)PPOAc
FeTPPOAc
11.5
5.6
FeT(4-OCH3)PPOAc
FeT(2-Cl)PPOAc
FeT(4-Cl)PPOAc
6.5
13.0
5.7
The molar ratios for (cis-stilbene,trans-stilbene):TBAP:ImH:catalyst are:(500, 500):170:10 (or 5 for the iron porphyrins):1
Analyzed by 1 H NMR
a
Without considering the cis to trans isomerization upon the oxidation of cis-stilbene
b
Obtained by control reaction using cis-stilbene:TBAP:ImH:catalyst in 500:170:10 (or 5 for the iron porphyrins):1
c
The corrected cis/trans-stilbene oxide by considering the cis to trans isomerization
catalytic activities compared to the electron-rich ones;
(ii) catalyst stability of the metalloporphyrins toward
oxidative degradation decreased in the order FeT(4-
-Cl)PPOAc≥FeT(2-Cl)PPOAc≥FeTPPOAc>>FeT(4-
OCH3)PPOAc≥MnT(4-OCH3)PPOAc>>MnT(2-
FeT(2-Cl)PPOAc the results are strongly in favor of a high
valent oxo metal species as the dominant active oxidant.
Acknowledgments Financial support of this work by the Institute
for Advanced Studies in Basic Sciences (IASBS) is acknowledged.
Cl)PPOAc>MnTPPOAc>MnT(4-Cl)PPOAc;
(iii)
stereoelectronic properties of substituents introduced at the
meso positions and those attached to the sulfur atom were
involved in the sulfoxide/sulfone molar ratio; (iv) appar-
ently, due to the steric effects of the meso substituents,
FeT(2-Cl)PPOAc and MnT(2-Cl)PPOAc showed very low
catalytic activities; (v) in the oxidation of methyl phenyl
sulfide, the iron porphyrins often have significantly higher
catalytic efficiencies compared to the corresponding man-
ganese porphyrins, but the order is not followed in the oxi-
dation of diallyl sulfide. Also, in the oxidation of olefins:
(i) the oxidative stability of the metalloporphyrins in reac-
tion condition decreased as FeT(2-Cl)PP(OAc)>FeT(4-Cl)
PP(OAc)>FeTPP(OAc)-≥MnT(4-OCH3)PP(OAc)>FeT(4-
O C H 3 ) P P ( O A c ) > M n T P P ( O A c ) > M n T ( 4 - C l )
PP(OAc)≥MnT(2-Cl)PP(OAc). The order is different from
that found in the oxidation of sulfides. In other words, the
relative stability of the series of metalloporphyrins seems
to depend on the of substrate as well as the steroelectronic
properties of the substituents at the periphery of the met-
alloporphyrins and other factors; (ii) the manganese por-
phyrins were usually more efficient catalysts compared to
the iron ones; (iii) in spite of the olefin dependence of the
catalytic activity of the metalloporphyrins, those with more
electron-donating substituents at the meso positions were
found to show higher catalytic activities; (iv) the oxidation
of cis- and trans-stilbene in a competitive reaction provided
evidence for the co-existence of high valent oxo metal spe-
cies and six-coordinate periodato complexes as the active
oxidants, although in the case of MnT(2-Cl)PPOAc and
References
1. J.E. Bäckvall, Selective Oxidation of Amines and Sulfides chap-
ter in Modern Oxidation Methods, 2nd edn, ed. by J. E. Bäckvall,
Chap. 8, pp. 277–313 (Wiley-VCH Verlag GmbH & Co. KGaA:
Weinheim, 2010)
2. E.N. Prilezhaeva, Sulfones and sulfoxides in the total synthesis of bio-
logically active natural compounds. Russ Chem Rev 69, 367 (2000)
3. S. Patai, Z. Rappoport, Synthesis of sulfones, sulfoxides and
cyclic sulfides (John Wiley, Chichester, 1994), pp. 109–254
4. N.S. Simpkins, Sulfones in organic synthesis (Pergamon Press,
Oxford, 1993)
5. I. Fernandez, N. Khiar, Recent developments in the synthesis and
utilization of chiral sulfoxides. Chem Rev 103, 3651 (2003)
6. A.M. Khenkin, R. Neumann, Oxygen Transfer from sulfoxides:
oxidation of alkylarenes catalyzed by a polyoxomolybdate,
[PMo12O40]3−. J Am Chem. Soc. 124, 4198 (2002)
7. B. Meunier, Metalloporphyrins as versatile catalysts for oxidation
reaction and oxidative dna cleavage. Chem Rev 92, 1411 (1992)
8. T.I. Reddy, R.S. Varma, Ti-beta-catalysed selective oxidation
of sulfides to sulfoxides using urea–hydrogen peroxide adduct.
Chem Commun 5, 471 (1997)
9. M.H. Ali, G.J.A. Bohnert, Facile and selective procedure for
oxidation of sulfides to sulfoxides with molecular bromine on
hydrated silica gel in dichloromethane. Synthesis 9, 1238 (1998)
10. W. Nam, S.Y. Oh, Y.J. Sun, J. Kim, W.K. Kim, S.K. Woo, W.
Shin, Factors affecting the catalytic epoxidation of olefins by iron
porphyrin complexes and H2O2 in protic solvents. J. Org. Chem.
68, 7903 (2003)
11. D. Mohajer, M. Abbasi, Solvent effects on catalytic epoxidation
of alkenes by Tetra-n-butylammonium periodate and (Tetraar-
ylporphyrinato) manganese(III). Eur. J. Inorg. Chem 20, 3218
(2008)
12. S. Zakavi, A. Abasi, A. Pourali, S. Talebzadeh, Metallopor-
phyrin-catalyzed chemoselective oxidation of sulfides with
1 3

J IRAN CHEM SOC (2015) 12:863–872
871
4-methoxyphenyl ones. J. Mol. Catal. A: Chem. 363–364, 153
(2012)
polyvinylpyrrolidone-supported hydrogen peroxide: a simple
catalytic system for selective oxidation of sulfides to sulfoxides.
Bull. Korean Chem. Soc. 33, 35 (2012)
28. S. Zakavi, T. Mokary yazdeli, Steroelectronic effects of the
meso-substituents on the catalytic performance of iron(III) meso-
tetraarylporphyrins: pyridyl and N-methylatedpyridyl groups
compared to phenyl, 4-methoxyphenyl and 4-sulfonatophenyl
ones. J. Mol. Catal. A: Chem 367, 108 (2013)
29. A.D. Adler, F.R. Longo, J.D. Finarelli, J. Goldmacher, J. Assour,
L. Korsakoff, A Simplified synthesis for msso-tetraphenylpor-
phin. J. Org. Chem. 32, 476 (1967)
13. C. Abebrese, Y. Huang, A. Pan, Z. Yuan, R. Zhang, Kinetic studies
of oxygen atom transfer reactions from trans-dioxoruthenium(VI)
porphyrins to sulfides. J. Inorg. Biochem. 105, 1555 (2011)
14. S. Campestrini, U. Tonellato, Manganeseporphyrin-catalysed het-
erogeneous and unusually chemioselective oxidations of sulfides
by monopersulfate in supercritical CO2. J. Mol. Catalysis A:
Chem 164, 263 (2000)
30. R.W.A. Johnstone, M.L.P.G. Nanes, M.M. Pereira, R.W.A. John-
stone, A.M.de.A.R. Gonsalves, A.C. Serra, Improved synthesis of
5,10,15,20-tetrakisaryl- and tetrakis-alkylporphyrins. Heterocy-
cles 43, 1425 (1996)
31. A.D. Adler, F.R. Longo, F. Kampas, J. Kim, On the preparation of
metalloporphyrins. J. Inorg. Nucl. Chem. 32, 2443 (1970)
32. H. Kobayashi, T. Higuchi, Y. Kaizu, H. Osada, M. Aoki, Elec-
tronic spectra of tetraphenylporphyrinatoiron(iii) methoxide.
Bull. Chem. Soc. Jpn. 48, 3137 (1975)
33. J.T. Groves, T.E. Nemo, Aliphatic hydroxylation catalyzed by
iron porphyrin complexes. J. Am. Chem. Soc. 105, 6243 (1983)
34. R.J. Abraham, G.E. Hawkes, M.F. Hudson, K.M. Smith, The
nuclear magnetic resonance spectra of porphyrins. Part X. I
carbon-13 nuclear magnetic resonance spectra of some meso-
tetraarylporphyrins and their metal chelates. J. Chem. Soc. Perkin
Trans. 2, 204 (1975)
35. R.A. Sheldon, J.K. Kochi, Metal-catalyzed oxidation of organic
compounds (Academic Press, New York, 1981), pp. 8–57
36. I.D. Cunningham, T.N. Danks, J.N. Hay, I. Hamerton, S.
Gunathilagan, C. Janczak, Stability of various metalloporphyrin
catalysts during hydrogen peroxide epoxidation of alkene. J. Mol.
Catal. A: Chem. 185, 25 (2002)
15. V. Mirkhani, M. Moghadam, S. Tangestaninejad, I. Mohammd-
poor-Baltork, H. Kargar, M. Araghi, Highly efficient oxidation of
sulfides with sodium periodate catalyzed by reusable silica sup-
ported Mn(Br8TPP)Cl and Mn(TPP)Cl catalysts under various
reaction conditions. Appl. Catal. A 353, 61 (2009)
16. A. Ghaemi, S. Rayati, S. Zakavi, N. Safari, Highly efficient oxi-
dation of sulfides to sulfones with tetra-n-butylammonium hydro-
gen monopersulfate catalyzed by β-tri- and tetra-brominated
meso-tetraphenylporphyrinatomanganese(III) acetate. Appl.
Catal. A 353, 154 (2009)
17. E. Sansiaume, R. Ricoux, D. Gori, J.-P. Mahy, Oxidation of
organic molecules in homogeneous aqueous solution catalyzed
by hybrid biocatalysts (based on the Trojan Horse strategy). Tet-
rahedron Asymmetry 21, 1593 (2010)
18. A. Rezaeifard, M. Jafarpour, H. Raissi, E. Ghiamati, A. Tootoon-
chi, Factors affecting the reactivity and selectivity in the oxida-
tion of sulfides with tetra-n-butylammonium peroxomonosul-
fate catalyzed by Mn(III) porphyrins: significant nitrogen donor
effects. Polyhedron 30, 592 (2011)
19. S. Rayati, S. Zakavi, E. Bohloulbandi, M. Jafarian, M. Rash-
vand avei, Comparative study of the catalytic activity of a series
of β-brominated Mn–porphyrins in the oxidation of olefins and
organic sulfides: Better catalytic performance of the partially bro-
minated ones. Polyhedron 34, 102 (2012)
20. S.M.G. Pires, M.M.Q. Simõesa, I.C.M.S. Santos, S.L.H. Rebelo,
M.M. Pereira, M.G.P.M.S. Nevesa, J.A.S. Cavaleiro, Biomimetic
oxidation of organosulfur compounds with hydrogen peroxide
catalyzed by manganese porphyrins. Appl. Catal. A 439–440, 51
(2012)
37. R. Koerner, M.M. Olmstead, A. Ozarowski, S.L. Phillips, P.M.
Van Calcar, K. Winkler, A.L. Balch, Possible intermediates in
biological metalloporphyrin oxidative degradation. Nickel, cop-
per, and cobalt complexes of octaethylformybiliverdin and their
conversion to a verdoheme. J. Am. Chem. Soc. 120, 1274 (1998)
38. M. Gouterman, Spectra of porphyrins. J. Mol. Spectrosc. 6, 138
(1961)
39. S. Zakavi, R. Omidyan, S. Talebzadeh, Porphine core saddling:
effects on the HOMO/LUMO gap and the macrocycle bond
lengths and bond angles. Polyhedron 49, 36 (2013)
40. J.E. Huheey, E.A. Keiter, R.L. Keiter, Inorganic chemistry: prin-
ciples of structure and reactivity, 4th edn. (HarperCollins College
Publishers, New York, 1993), pp. 187–188
41. C. Elschenbroich, Organometallics, 3rd ed., translated by J.
Oliveira and C. Elschenbroich. (Wiley-VCH Verlag GmbH & Co.
KGaA, Weinheim, 2006) p. 280
21. D. Mohajer, S. Tangestaninejad, Efficient catalytic epoxidation of
alkenes by a manganese porphyrin and periodate in the presence
of imidazole. J. Chem. Soc., Chem. Commun. 3, 240 (1993)
22. D. Mohajer, S. Tangestaninejad, Efficient olefin epoxidation with
tetrabutylammonium periodate catalyzed by manganese porphy-
rin in the presence of imidazole. Tetrahedron Lett. 35, 945 (1994)
23. D. Mohajer, R. Tayebee, H. Goudarziafshar, Sodium periodate
epoxidation of alkenes catalysed by manganese porphyrins. J.
Chem. Research (S) 2, 168 (1999)
42. B. Figgis, M.A. Hitchman, Ligand field theory and its applica-
tions (Wiley-VCH, New York, 2000), pp. 56–57
24. D. Mohajer, G. Karimipour, M. Bagherzadeh, Reactivity studies
of biomimetic catalytic epoxidation of alkenes with tetrabutyl-
ammonium periodate in the presence of various manganese por-
phyrins and nitrogen donors: significant axial ligand π-bonding
effects. New J. Chem. 28, 740 (2004)
25. S. Zakavi, F. Heidarizadi, S. Rayati, Comparative study of cata-
lytic activity of some biomimetic models of cytochrome P450 in
oxidation of olefins with tetra-n-butylammonium periodate: elec-
tron-rich Mn-porphyrins versus the electron-deficient ones. Inorg.
Chem. Commun. 14, 1010 (2011)
26. S. Zakavi, L. Ebrahimi, Substitution effects on the catalytic activ-
ity of Mn(III) porphyrins in epoxidation of alkenes with iodo-
sylbenzene: A comparison between the electron-rich and elec-
tron-deficient porphyrins. Polyhedron 30, 1732 (2011)
27. S. Zakavi, A.G. Mojarrad, S. Rayati, Substituent effects on the
catalytic activity of a series of manganese meso-tetra(aryl)
porphyrins: (2-, 3-, 4)-Pyridyl, 4-sulfonatophenyl and 3-sul-
fonato-4-methoxyphenyl groups compared to phenyl and
43. S. Zakavi, R. Omidyan, L. Ebrahimi, F. Heidarizadi, Substitution
effects on the UV–vis and 1H NMR spectra of the dications of
meso and/or β substituted porphyrins with trifluoroacetic acid:
electron-deficient porphyrins compared to the electron-rich ones.
Inorg. Chem. Commun. 14, 1827 (2011)
44. P.S. Traylor, D. Dolphin, T.G. Traylor, Sterically protected
hemins with electronegative substituents: efficient catalysts for
hydroxylation and epoxidation. J. Chem. Soc. Chem. Commun 5,
279 (1984)
45. A.C. Serra, E.C. Marçalo, M.A.d’A. Rocha Gonsalves, A view
on the mechanism of metalloporphyrin degradation in hydrogen
peroxide epoxidation reactions. J. Mol. Catal. A: Chem 215, 17
(2004)
46. R.D. Arasasingham, G.X. He, T.C. Bruice, Mechanism of
manganese porphyrin-catalyzed oxidation of alkenes. Role of
manganese(IV)-oxo species. J. Am. Chem. Soc. 115, 7985 (1993)
1 3

872
J IRAN CHEM SOC (2015) 12:863–872
47. W. Nam, M.H. Lim, H.J. Lee, C. Kim, Evidence for the partici-
pation of two distinct reactive intermediates in iron(iii) porphy-
rin complex-catalyzed epoxidation reactions. J. Am. Chem. Soc.
122, 6641 (2000)
48. W. Nam, S.W. Jin, M.H. Lim, J.Y. Ryu, C. Kim, Anionic ligand
effect on the nature of epoxidizing intermediates in iron porphy-
rin complex-catalyzed epoxidation reactions. Inorg. Chem. 41,
3647 (2002)
1 3