Microwave-assisted epoxidation of simple alkenes in the presence of hydrogen peroxide

Article abstract of DOI:10.1080/00397910500278479

A novel application of microwave irradiation for the epoxidation of some simple alkenes, in which hydrogen peroxide was used as an oxidant together with sodium tungsten and phosphorous acid under phase-transfer catalytic (PTC) conditions, is described as a new environmentally benign method. In comparison with conventional heating, the microwave process is a very useful alternative for introducing of the oxirane ring into some unsaturated hydrocarbons because of reduction of the reaction time and increase in yield. Copyright Taylor & Francis, Inc.

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Microwave‐Assisted
Epoxidation of Simple Alkenes
in the Presence of Hydrogen
Peroxide
a
b
a
D. Bogdal , M. Lukasiewicz , J. Pielichowski & S.
a
Bednarz
a
Faculty of Chemical Engineering and Technology ,
Politechnika Krakowska , Krakow, Poland
b
Department of Carbohydrates Technology ,
Agricultural University of Krakow , Krakow, Poland
Published online: 21 Aug 2006.
To cite this article: D. Bogdal , M. Lukasiewicz , J. Pielichowski & S. Bednarz
(2005) Microwave‐Assisted Epoxidation of Simple Alkenes in the Presence of
Hydrogen Peroxide, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 35:23, 2973-2983
To link to this article: http://dx.doi.org/10.1080/00397910500278479
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Synthetic Communications , 35: 2973–2983, 2005
Copyright # Taylor & Francis, Inc.
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910500278479
Microwave-Assisted Epoxidation
of Simple Alkenes in the Presence
of Hydrogen Peroxide
D. Bogdal
Faculty of Chemical Engineering and Technology, Politechnika
Krakowska, Krakow, Poland
M. Lukasiewicz
Department of Carbohydrates Technology, Agricultural University
of Krakow, Krakow, Poland
J. Pielichowski and S. Bednarz
Faculty of Chemical Engineering and Technology, Politechnika
Krakowska, Krakow, Poland
Abstract: A novel application of microwave irradiation for the epoxidation of some
simple alkenes, in which hydrogen peroxide was used as an oxidant together with
sodium tungsten and phosphorous acid under phase-transfer catalytic (PTC) con-
ditions, is described as a new environmentally benign method. In comparison with con-
ventional heating, the microwave process is a very useful alternative for introducing of
the oxirane ring into some unsaturated hydrocarbons because of reduction of the
reaction time and increase in yield.
Keywords: Alkenes, epoxidation, hydrogen peroxide, microwave
Received in Poland March 18, 2005
Address correspondence to D. Bogdal, Faculty of Chemical Engineering and
Technology, Politechnika Krakowska, ul. Warszawska 24, 31-155 Krakow, Poland.
Tel./Fax: þ48 12 628-20-38; E-mail: pcbogdal@cyf-kr.edu.pl
2
973

2974
D. Bogdal et al.
INTRODUCTION
The epoxidation reactions of carbon–carbon double bonds are very useful
transformations in organic synthesis because of the high reactivity of
resulting oxirane rings, which are easy to open in a number of different
[1]
chemical transformation to give hydroxy derivatives as main products.
Use of aqueous hydrogen peroxide for the epoxidation of carbon–carbon
double bonds under phase transfer catalytic (PTC) conditions was described
[
2]
by Venturello et al.,
ammonium salt as a combined catalyst and chlorinated hydrocarbons as
who employed Na WO -H PO -quaternary
2 4 3 4
[
3]
solvents. However, Ishii et al. improved PTC protocol by using tungsten-
based heteropolyacid and N-cetylpyridinium chloride in a chloroform/water
biphasic system; a more effective solvent- and halide-free version of this
[4]
process was recently published by Sato et al. They found that the substi-
tution of ammonium chlorides with ammonium hydrogen sulfates under sol-
ventless organic/aqueous biphasic conditions in the presence of
(aminomethyl)phosphonic acid led to the increase of the reaction yields as
well as made the process clean, safe, and operationally simple.
Recently, it has been shown that application of microwave irradiation led
[
to an acceleration of the reaction including oxidation with hydrogen
5]
[6]
peroxide. In particular, such a phenomenon is observed for many PTC-
[
7]
catalyzed reactions, so we decided to explore such procedures for epoxida-
tion of alkenes under microwave irradiation employing aqueous hydrogen
peroxide. Because one of drawbacks of a number of procedures given in litera-
ture is the preparation of catalyst systems prior to reactions, we planned to
elaborate a microwave procedure in which only commercially available
reagents could be used.
RESULTS AND DISCUSSION
Under microwave irradiation, the epoxidation reactions of simple alkenes were
carried out employing the modification of the classic Venturello’s procedure
[
2]
given for PTC conditions. In the course of the research, we obtained
the best results when an 8% solution instead of a 30% solution of hydrogen
peroxide was applied in the presence of Na WO , H PO , and Aliquat 336
2
4
3
4
as a PTC catalyst in a two-phase system water/ethylene chloride (Scheme 1).
Scheme 1. Epoxidation of alkenes in the presence of hydrogen peroxide.

Epoxidation of Simple Alkenes
2975
The experimental procedure involves
.
a
Na WO 2H O, a 40% solution of phosphoric acid, and an 8% solution of
simple mixing of
2
4
2
hydrogen peroxide followed by the addition of Aliquat 336 in ethylene
chloride in a 1 : 5 : 140 : 1 molar ratio. Then, the mixture was stirred vigorously
and an alkene was added to obtain the molar ratio of alkene to hydrogen
peroxide of 4 : 5, while the pH of the solution was maintained at 1.6 by
using a small amount of a 30% solution of sulfuric acid. The mixture was
placed in an open vessel and irradiated in the microwave reactor at 708C
for the time needed for the consumption of hydrogen peroxide (ca. 15 min;
monitored by the color reaction with FeCl and K Fe[CN] ); then in 15-min
3
3
6
intervals, an 8% solution of hydrogen peroxide was added so that the final
molar ratio of hydrogen peroxide to alkene was 5 : 1 and total reaction time
1 h. The same experiments were run under conventional conditions, and the
results of all the experiments are summarized in Table 1.
It is worth of pointing out that in the case of conventional reactions the
final yields of the oxiranes was always lower than under microwave
irradiation. Even though the reaction time under conventional conditions
was longer, final products were separated in lower yield than in microwave
experiments. For example, the yield of 1,2-epoxydodecane after 210 min
reached only 85%.
In general, this protocol was most effective for simple unsubstituted linear
or cyclic alkenes, whereas in the case of substituted olefins, yields of these
reactions were lower. For example, after the epoxidation of a-pinene and
trans-stillbene under microwave conditions, the desired products were
afforded in 45 and 53% yields, respectively.
In the case of the epoxidation of N-allylcarbazole under conventional
conditions, no traces of epoxy compound (i.e., N-[2,3-epoxypropyl]carbazole)
were detected. The epoxidation under microwave irradiation allowed us to
obtain N-(2,3-epoxypropyl)carbazole in 14% yield after 1.5 h. However, the
yield was still low; according to our knowledge, it was first example of epoxi-
dation of N-allylcarbazole. All epoxidation reaction attempts that followed
[
12]
[13]
protocols described by Rudolph et al.,
et al.
Yamaguchi et al.,
in the presence of hydrogen peroxide failed; however, other
and Pillai
[14]
alkenes were epoxidized, and we could only recover N-allylcarbazole from
the reaction mixtures with ,95% yield. Eventually, to obtain a reference
sample of N-(2,3-epoxypropyl)carbazole, we managed to prepare it by the
alkylation of carbazole with epichlohydrin under PTC conditions, applying
microwave protocols as well.
To avoid compounds containing halogens such as ethylene chloride and
PTC catalyst, ethylene chloride was replaced by toluene and halogen-free
PTC catalyst was used (i.e., hexadecyl-trimethylammonium hydrogen-
sulphate). The yield of these transformations was lower (for instance, 2,3-
epoxyoctene was obtained in 68% yield in comparison with 90%), but it
could be an interesting greener alternative for such epoxidation reactions. A
solvent-free protocol under microwave conditions afforded epoxy

2976
D. Bogdal et al.
Table 1. Epoxidation of simple alkenes in the presence of hydrogen peroxide.
a
Yield (%)
mp (8C)/bp (8C/mmHg)
Product
no.
[
8]
Substrate
Microwave Conventional
Exp.
Lit.
98
58
89
27
91
62
123–124/15 124–125/15
b
c
d
1
b
6
3
9
2
0
0
65
76
92–93/15
61–63/15
94/15
d
2
3
b
68
32
60–62/15
d
4
5
45
35
38
10
100–101/50 102/50
114–117/760 115–117/760
6
7
53
14
44
0
63–67
67–69
g
[9]
109–111
108–112
f
[10]
8
9
98
69
68
118–120/15 118/15
97
47–50
49–51
f
[11]
110/5
10
95
40
112/5
a
b
Isolated yield. The reaction time: 60 min.
The reaction carried out in toluene using hexadecyltrimethylammonium
hydrogensulphate.
c
2 2
The reaction in the presence of 30% H O .
d
The reaction in the solventless system.
Yield of 5,10-dioxatricyclo[7.1.04,6]decane.
Yield of 1,3-oxabicyclo[10.1.0.]trideca-4,8-diene.
e
f
g
The compound was obtained by two other methods presented in the experimental
section.

Epoxidation of Simple Alkenes
2977
compounds in much lower yield. For example, 1,2-epoxyoctane, 1,2-epoxyde-
cane, and 1,2-epoxydodecane were given in 32, 30, and 28% yields,
respectively.
As far as the biphasic epoxidation with aqueous hydrogen peroxide is
concerned, the use of lipophilic quartenary ammonium salts is crucial for
[2–4]
the process.
We have shown that in the microwave-assisted reactions
there is no need for the preparation of such ammonium salts prior to
reactions, and they could be successfully substituted with commercially
[
6a]
available ammonium salts.
However, the study on the application of
different PTC catalysts (Fig. 1) has shown that yield of the epoxidation
reactions was strongly dependent on the types of salt cations. Cations that
consist of long aliphatic chains were preferable as PTC catalysts, and the
origin of an anion seems to have smaller influence. The lowest activity is
observed for a non-salt-like catalyst such as polyethylene glycol (yield
about 10%) or crown ethers (traces). The conversions of 1-dodecene to 1,2-
epoxydodecane in the presence of different catalysts are shown in Fig. 1.
Discussed effects are observed under both microwave and conventional
conditions, which shows that they are independent of a heating method.
In conclusion, we have described an efficient microwave-assisted
protocol for the epoxidation of carbon–carbon double bonds that is a modifi-
[
2–4]
cation of previous methods
of the synthesis of oxiranes by using hydrogen
peroxide under PTC conditions. Because of the reduction of reaction times,
the subsequent ring-opening reactions of the oxirane rings were limited,
which influences both yield and selectivity of the processes. The advantages
Figure 1. Conversion of 1-dodecene to 1,2-epoxydodecene in the presence of differ-
ent PTC catalysts (1 h, 708C): A, Aliquat 336; B, triethylbenzylammonium chloride;
C, tetrabutylammonium bromide; D, PEG 2000; E, tetrabutylammonium hydrogensul-
phate; and F, triphenylphosphine hydrobromide.

2978
D. Bogdal et al.
of this microwave protocol include application of commercially available 8%
or 30% aqueous solutions of hydrogen peroxide as well as PTC catalysts,
shorter reaction times, and simple setup.
EXPERIMENTAL
All the chemicals were purchased from Aldrich and used as received. The
reactions were carried out in a multimode microwave reactor with a continuous
power regulation (PLAZMATRONIKA, Poland), which is equipped with
magnetic stirrer and two inlets on the top and one side of the reactor. The inlets
allowed applying an upright condenser and introducing a fiber-optical sensor
(ReFlex, Nortech), which was used to control temperature during microwave
experiments. IR spectra were recorded on FT-IR Biorad FTS-165 spectropho-
1
tometer as liquids on KBr disks or as pellets with KBr. H NMR spectra were
collected on Tesla 487C (80-MHz) spectrometer using TMS as an internal
standard. GC/MS spectra were determined on GC/MS 5890 series II Hewlett-
Packard gas chromatograph equipped with Ultra 2 (25 m ꢀ 0.25 mm ꢀ
0.25 mm) column with Hewlett-Packard 5971 series mass selective detector.
General Method for the Epoxidation of Alkenes
All the reactions were carried out according the epoxidation procedure given
for 1-dodecene, which is representative of the general procedure employed for
microwave and conventional conditions.
Microwave Procedure for the Epoxidation of 1-Dodecane
Sodium tungstate dihydrate (0.72 mmol, 0.24 g), 40% phosphoric acid
w
(
1.72 mmol, 0.17 g), 8% hydrogen peroxide (35 mmol, 4.50 g), Aliquat 336
trioctylmethylammonium chloride, 0.1 g), and ethylene chloride (2.1 mL)
(
were mixed together. Then, the mixture was intensively stirred for 15 min at
room temperature. After that, 1-dodecene (28 mmol, 4.7 g) was added, while
the appropriate pH (ca.1.6) was estimated using 30% solution of sulfuric
acid. The intensively stirred mixture was placed in a long-neck open vessel
and irradiated in the microwave reactor at 708C for time needed for the
consumption of hydrogen peroxide (ca. 15 min; monitored by the color
reaction with FeCl3 and K Fe[CN] ), and then in an 8% solution of
3
6
hydrogen peroxide was added 15-min intervals so that the final molar ratio
of hydrogen peroxide to alkene was 5 : 1 and total reaction time was 1 h.
After completion of the reaction monitored by GC/MS, the phases were
separated, the organic layer was evaporated, and the crude product was
purified by Kugelrohr distillation at vacuum to afford 5.05 g (98% yield) of
1
,2-epoxydodecane.

Epoxidation of Simple Alkenes
2979
Conventional Procedure the Epoxidation of 1-Dodecane
Sodium tungstate dihydrate (0.72 mmol, 0.24g), 40% phosphoric acid
w
(
1.72 mmol, 0.17g), 8% hydrogen peroxide (35 mmol, 4.50 g), Aliquat 336
trioctylmethylammonium chloride, 0.1 g) and ethylene chloride (2.1mL) were
(
mixed together. Then, the mixture was intensively stirred for 15 min at room
temperature. After that 1-dodecene (28 mmol, 4.7 g) was added, while the appro-
priate pH (ca.1.6) was estimated using a 30% solution of sulfuric acid. The inten-
sivelystirredmixturewasplacedina long-neckopenvesselandthermostatedina
water bath at 708C; then, in 15-min intervals, an 8% solution of hydrogen
peroxide was added so that the final molar ratio of hydrogen peroxide to
alkene was 5 : 1 and total reaction time was 1 h. After completion of the
reaction monitored by GC/MS, the phases were separated, the organic layer
was evaporated, and the crude product was purified by Kugelrohr distillation
at vacuum to afford 3.2 g (62% yield) of 1,2-epoxydodecane.
1
1
,2-Epoxydodecane (1): IR (KBr) v ¼ 2956 (s), 2924 (s), 2866 (s), 1467 (m),
2
1
129 (w), 917 (w), 834 (m), 772 (m) cm . MS m/z ¼ 183 [(M-1), 1%], 141
(
1%), 127 (3%), 113 (5%), 98 (8%), 85 (23%), 71 (100%), 67 (49%), 57 (49%),
1
4
3 (69%), 29 (26%). H NMR (CDCl ) d ¼ 0.93 (t, 3H, CH –), 1.18–1.55
2
3
3
(
m, 18H, –CH –), 2.28 (dd, 1H, –CH), 2.56 (dd, 1H, –CH), 2.74 (m, 1H,
CH–) ppm.
–
1
1
1
4
,2-Epoxydecane (2): IR (KBr) v ¼ 2957 (m), 2926 (s), 2856 (s), 1467 (m),
2
1
130 (w), 1079 (w), 916 (m), 845 (m), 723 (w) cm . MS m/z ¼ 155 [(M-1),
%], 113 (8%), 98 (9%), 85 (16%), 71 (100%), 68 (45%), 57 (41%), 43 (64%),
1
1 (71%), 29 (32%). H NMR (CDCl ) d ¼ 0.90 (t, 3H, CH –), 1.10–1.60
3
3
(
m, 18H, –CH –), 2.29 (dd, 1H, –CH), 2.54 (dd, 1H, –CH), 2.71 (m, 1H,
2
–
CH–) ppm.
1
1
1
,2-Epoxyoctane (3): IR (KBr) v ¼ 2958 (s), 2930 (s), 2859 (s), 1467 (m),
2
1
379 (m), 1130 (m), 1072 (w), 918 (m), 847 (m), 725 (m) cm . MS m/z ¼
27 [(M-1), 1%], 99 (5%), 85 (14%), 71 (100%), 69 (25%), 58 (45%), 43
1
(
32%), 41 (69%), 29 (36%). H NMR (CDCl ) d ¼ 0.91 (t, 3H, CH –),
3
3
1
2
.31–1.53 (m, 10H, –CH –), 2.47 (dd, 1H, –CH), 2.74 (dd, 1H, –CH),
2
.91 (m, 1H, –CH–) ppm.
5
,7,7-Trimethyl-3-oxa-tricyclo[4.1.1.02,4]octane (4): IR (KBr) v ¼ 2978
(
s), 2953 (s), 2917 (s), 1469 (m), 1460 (m), 1377 (m), 1196 (m), 1097 (m),
2
1
1
045 (w), 934 (m), 867 (m), 840 (m), 767 (m) cm . MS m/z ¼ 152
[
(
(Mþ), 1%], 137 (18%), 123 (2%), 119 (6%), 109 (38%), 95 (20%), 83
1
40%), 67 (100%), 55 (38%), 53 (18%), 43 (58%), 41 (61%), 27 (3%). H
NMR (CDCl ) d ¼ 0.94 (s, 6H, CH –), 1.29 (m, 3H, –CH –), 1.62 (s, 2H,
3
3
3
–
CH –), 1.74–2.00 (m, 4H, –CH–, –CH –), 3.07 (t, 1H, –CH–) ppm.
2 2

2980
D. Bogdal et al.
2
1
-(Chloromethyl)oxirane (5): IR (KBr) v ¼ 3004 (m), 2963 (m), 2926 (m),
2
438 (m), 1398 (m), 1267 (m), 1137 (m), 927 (s), 854 (s), 761 (s) cm . MS
1
m/z ¼ 64 (5%), 62 (16%), 57 (100%), 49 (26%), 42 (8%), 31 (25%), 29
1
(
(
26%), 27 (47%). H NMR (CDCl ) d ¼ 2.69 (m, 1H, –CH–), 2.89
3
m, 1H, –CH–), 3.26 (m, 1H, –CH–), 3.57 (m, 1H, –CH–) ppm.
2
,3-Diphenyloxirane (7): IR (KBr) v ¼ 3036 (m), 2990 (m), 1604 (m), 1501
2
1
(m), 1463 (m), 1348 (m), 1095 (m), 836 (m), 749 (s), 697 (s) cm . MS m/
z ¼ 196 [(M þ ), 100%], 195 (42%), 178 (14%), 167 (84%), 152 (9%), 132
(
(
1%), 118 (4%), 105 (11%), 90 (69%), 89 (60%), 77 (20%), 63 (16%), 51
1
13%). H NMR (CDCl ) d ¼ 7.06–7.22 (m, 10H, ArH–), 7.44 (s, 2H,
3
–
CH–) ppm.
5
2
,10-Dioxa-tricyclo[7.1.0.4,6]decane (8): IR (KBr) v ¼ 2939 (s), 2916 (m),
848 (s), 1463 (m), 1437 (m), 1090 (w), 1050 (w), 1020 (m), 941 (m), 913
2
1
(
w), 868 (m), 780 (m) cm . MS m/z ¼ 121 (0.5%), 111 (0.5%), 95 (1%),
8
3
3 (13%), 79 (14%), 69 (11%), 67 (43%), 55 (39%), 43 (23%), 41 (100%),
1
9 (43%), 29 (22%), 27 (19%). H NMR (CDCl ) d ¼ 2.13 (m, 8H,
3
–
CH –), 2.89 (m, 4H, –CH–) ppm.
2
cis-9-Oxabicyclo[6.1.0.]nonane (9): IR (KBr) v ¼ 2971 (m), 2928 (s), 2855
(
(
(
(
(
m), 1471 (m), 1464 (m), 1289 (w), 1185 (w), 1016 (m), 923 (m), 846 (s), 767
21
s), 741 (m) cm . MS m/z ¼ 126 [(M þ ), 2%], 111 (6%), 99 (1%), 97
20%), 83 (29%), 69 (19%), 67 (53%), 55 (100%), 41 (64%), 39 (43%), 29
1
1
24%), 27 (25%). H NMR (CCl4) H NMR (CDCl ) d ¼ 0.95–1.88
3
m, 2H, –CH–), 2.13 (m, 2H, –CH –), 2.89 (m, 10H, –CH –) ppm.
2
2
1
2
3-Oxabicyclo[10.1.0.]tridecadiene (10): IR (KBr) v ¼ 2931 (s), 2918 (s),
866 (s), 1658 (w), 1438 (s), 1405 (w), 1312 (m), 1284 (w), 1190 (m), 1108
2
1
(m), 978 (s), 958 (s), 874 (s), 766 (m), 703 (s), 609 (m) cm . MS m/
z ¼ 178 [(M þ ), 1%], 163 (2%), 149 (6%), 134 (3%), 123 (21%), 109
(
20%), 97 (16%), 93 (22%), 81 (42%), 79 (71%), 67 (90%), 54 (80%), 41
1
(100%), 27 (33%). H NMR (CDCl ) d ¼ 2.37 (m, 4H, –CH –, –CH 55 ),
3
2
2
.78 (m, 4H, –CH –), 3.18 (m, 4H, –CH –), 4.38 (m, 2H, –CH–), 5.45
2 2
(m, 4H, –CH –, –CH 55 ) ppm.
2
Microwave Procedure for the Synthesis
[
of N-(2,3-Epoxypropyl)carbazole
15]
Carbazole (30 mmol, 5.0 g), potassium carbonate (120 mmol, 16.5 g),
powdered potassium hydroxide (30 mmol, 1.7 g), epichlorohydrin
(195 mmol, 18 g), and tetrabutylammonium bromide (15 mmol, 0.50 g) were
placed in a toluene solution (90 mL) in a one-necked 250-mL round-bottom
flask equipped with an upright condenser. The reaction mixture was stirred

Epoxidation of Simple Alkenes
2981
quickly with a magnetic stirrer and irradiated with the full power in the
microwave reactor Plazmatronika for 5 min; then, the power of microwave
irradiation was reduced to 50%, and the reaction was continued for another
5
min. The mixture boiled intensively during the reaction, and its temperature
(
measured by means of a pyrometer) was maintained at 105–1068C. The
reaction mixture was passed through a funnel to remove salts, and the salt
was rinsed with toluene and acetone. The solvent was removed from the
filtered solution to give a yellowish mass that was dissolved and recrystallized
from ethanol to afford 6.0 g (90% yield; mp 109–1118C) of N-(2,3-
epoxypropyl)carbazole.
Conventional Procedure for the Synthesis
15]
of N-(2,3-Epoxypropyl)carbazole
[
Carbazole (26 mmol, 4.3 g), potassium carbonate (174 mmol, 24.1 g),
powdered potassium hydroxide (19 mmol, 1.05 g), epichlorohydrin
(
175 mmol, 16.2 g), and tetrabutylammonium bromide (2.6 mmol, 0.83 g)
were placed in an acetone solution (100 mL) in a one-necked 250-mL
round-bottom flask equipped with an upright condenser. The reaction
mixture was stirred quickly with a mechanical stirrer and heated at a water
bath at 528C for 1 h. Then, potassium carbonate (87 mmol, 12.0 g) and
powdered potassium hydroxide (19 mmol, 1.05 g) were added to the
mixture, and the reaction was continued for another 3 h. Then, inorganic sub-
stances were separated by filtration, and the solid was rinse with acetone. The
solvent was removed from the filtered solution to give a yellowish mass that
was dissolved and recrystallized from ethanol to afford 5.3 g (88% yield; mp
1
09–1118C) of N-(2,3-epoxypropyl)carbazole.
N-(2,3-Epoxypropyl)carbazole (6): IR (KBr) v ¼ 3048 (w), 1625 (m), 1595
(
m), 1485 (m), 1455 (s), 1417 (m), 1350 (m), 1328 (m), 1224 (m), 1152 (m),
2
1
9
01 (m), 839 (w), 747 (s), 720 (s), 631 (w), 563 (w), 458 (w) cm . MS m/
z ¼ 224 [(M þ 1), 10%], 223 [(M þ ), 57%], 204 (1%), 192 (2%), 180
(
(
100%), 166 (4%), 152 (14%), 140 (4%), 127 (2%), 112 (2%), 90 (2%), 76
1
2%), 63 (3%), 39 (2%). H NMR (CDCl ) d ¼ 2.602–2.626 (m, 1H,
3
–
CH ), 2.831–2.86 (m, 1H, –CH ); 3.367–3.416 (m, 1H, –CH–); 4.409–
2 2
4.704 (m, 2H, –CH –); 7.27–7.343 (m, 2H, Ar-H); 7.485–7.552 (m, 4H,
2
Ar-H); 8.123–8.156 (d, 2H, Ar-H) ppm.
ACKNOWLEDGMENTS
This work was undertaken as part of the EU-sponsored D32 COST Program
(
Chemistry in High-Energy Microenvironments).

2982
D. Bogdal et al.
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Epoxidation of Simple Alkenes
2983
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