Synthesis of Epoxides
745
Table 6. Comparison of the epoxidation of 1-octene with different catalytic systems
Catalyst system
Catalyst composition
Reaction
time [h]
Reaction
temperature [◦C]
Solvent
Yield
[mol-%]
Present systemA
VenturelloB
IshiiC
NoyoriD
MizunoE
XiF
[(CH3(CH2)17)2N(CH3)2]3[PW4O32] (1)
2
1
5
4
10
7
60
70
60
90
32
45
Dioxan
97
81
80
94
90
79
Na2WO4 + H3PO4 + quaternary ammonium chloride
1,2-Dichloroethane
Chloroform
Toluene
MeCN
Mixed solventG
H3PW12O40 + cetylpyridinium chloride
Na2WO4·2H2O + NH2CH2PO3H2 + [CH3(n-C8H17)3N]HSO4
[γ-SiW10(H2O)2O34](Bu4N)4
[π-C5H5N(CH2)15CH3]3[PW4O16
]
APresent paper; Bref. [10]; Cref. [11]; Dref. [12]; Eref. [13]; Fref. [24]. GTrimethylbenzene and trioctylphosphate.
N 1.17%.) νmax(KBr)/cm−1 1479, 1080, 981, 895, 807, 729,
599, 517. δP (MAS) 2.1, −15.0.
were recorded at 9.4T on a Bruker Avance-400 wide-bore spec-
trometer. The 31P MAS NMR spectra of solid catalyst with
high-power proton decoupling were obtained at 161.9 MHz with
a broad band MAS probe head using 4-mm ZrO2 rotors, a 3.8-µs
pulse, 30-s repetition time, and 128 scans, with samples spun at
10 kHz and referenced to 85% H3PO4. GC analyses were per-
formedonaShimadzuGC-9AMwithaflameionizationdetector
equipped with an SE-54 capillary column (internal diameter
0.25 mm, length 30 m). GC-MS were recorded on a Finnigan
Trace DSQ (Thermo Electron Corporation) at an ionization volt-
age of 70 eV equipped with a DB-5 capillary column (internal
diameter 0.25 mm, film thickness 0.25 µm, length 30 m). Chem-
icalelementalanalysisofthecatalystswasdoneonaninductively
coupled plasma-atomic emission spectrometer (IRIS ER/S), and
C, H, and N contents were measured on a Elementar Vario EL
spectrometer. 1H NMR and 13C NMR spectra were recorded on
a Bruker AM-400 and Varian Mercury 300 MHz spectrometer
with TMS as an internal standard and CDCl3 as solvent unless
otherwise noted.
[π-C5H5N(CH2)13CH3]3[PW4O28]: (Anal. calc. for
C57H102N3PW4O28: C 33.49, H 4.99, N 2.06, P 1.52. Found:
C 33.87, H 4.77, N 1.97, P 1.46%.) νmax(KBr)/cm−1 1174, 1080,
953, 890, 821, 774, 722, 685, 645, 594. δP (MAS) 6.1, −1.3,
−7.7, −13.2, −15.8, −23.4.
[π-C5H5N(CH2)15CH3]3[PW4O28]: (Anal. calc. for
C63H114N3PW4O28: C 35.55, H 5.36, N 1.98, P 1.46. Found: C
35.77, H 5.17, N 1.77, P 1.42%.) νmax(KBr)/cm−1 1486, 1173,
1078, 978, 896, 809, 679, 596, 521. δP (MAS) 6.3, −1.6, −5.7,
−13.0, −15.2, −16.1.
[π-C5H5N(CH2)15CH3]3[PW12O40]: To
a solution of
cetylpyridinium bromide (5.2 mmol) in distilled water (70 mL)
was added dropwise H3PW12O40 (1.7 mmol) in distilled water
(10 mL) with stirring at ambient temperature and a white pre-
cipitate formed immediately. After being stirred continuously
for 3.5 h, the resulting mixture was filtered, washed several
times with distilled water, and then dried at room temperature.
νmax(KBr)/cm−1 1464, 1173, 1080, 978, 896, 830–740, 678,
522. δP (MAS) −15.4.
Catalytic Reaction
[π-C5H5N(CH2)11CH3]3[PW12O40]: To a solution of 1-
dodecylpyridinium chloride (0.51 mmol) in distilled water
(7 mL) was added dropwise H3PW12O40 (0.17 mmol) in dis-
tilled water (1 mL) with stirring at ambient temperature to form
a white precipitate immediately. After being stirred continu-
ously for 3.5 h, the resulting mixture was filtered, washed several
times with distilled water, and then dried at room temperature.
νmax(KBr)/cm−1 1463, 1171, 1082, 979, 898, 832–741, 677,
520. δP (MAS) −15.3.
The catalytic reactions were performed in a 25-mL two-necked
round-bottomed flask equipped with a septum, a magnetic stir-
ring bar, and a reflux condenser. The epoxidation was carried
out as follows: catalyst, solvent, substrate, and H2O2 (30% aq.)
were placed in the reaction flask. The reaction was carried out
at 333 K and detected by TLC accompanied with GC. After the
reaction was over, the organic layer was analyzed by GC. The
yield of products was calculated from the peak areas using an
internal standard method. The epoxide products were identified
byGC-MS(FinniganTraceDSQ).Atthesametime, assignments
of products were made by comparison with retention times of
authentic samples. The carbon balance in each experiment was
in the range of 95–100%. After reaction, the catalyst was precip-
itated from the solvent and was separated by centrifugation. For
the blank reaction, no catalyst was added to the flask and other
conditions were the same as above. For reactions in the absence
of molecular oxygen, the reaction vessel was purged with argon
and then capped with a rubber septum stopper. For reactions in
the presence of molecular oxygen, the reaction vessel was not
purged with argon or capped with a rubber septum.
[(CH3(CH2)17)2N(CH3)2]3[PW12O40]: To a solution of
dioctadecyldimethyl ammonium chloride (0.51 mmol) in
distilled water (7 mL) was added dropwise H3PW12O40
(0.17 mmol) in distilled water (1 mL) with stirring at ambient
temperature and a white precipitate formed immediately. After
being stirred continuously for 3.5 h, the resulting mixture was
filtered, washed several times with distilled water, and then dried
at room temperature. νmax(KBr)/cm−1 1467, 1171, 1081, 980,
896, 831–740, 678, 521. δP (MAS) −15.5.
[π-C5H5N(CH2)15CH3]3[PW4O16] (Xi’s catalyst) was syn-
thesized by the method reported in ref. [22]. (Anal. calc. for C
39.08, H 5.95, N 2.17, P 1.60. Found: C 38.34, H 6.17, N 2.31, P
1.52%.) νmax(KBr)/cm−1 1087, 1032, 942, 884, 776, 719, 686,
625, 582, 543. δP (MAS) 4.9, −2.8, −10.1.
For the characterization of diene products, the procedure was
as follows:
The precipitate was removed by centrifugation and filtration,
and the filtrate extracted with EtOAc (30 mL × 3); the organic
layer was collected and washed with water and brine, then dried
with anhydrous Na2SO4. After evaporation of the solvent under
reduced pressure, the residue was purified by column chromato-
graphy (light petroleum/ethyl acetate, 10:1) to give epoxides as a
Characterization Techniques
Infrared spectra were recorded on a Nocolet FTIR-360 spec-
trometer. The catalysts were measured using 2–4% (w/w) KBr
pellets prepared by manual grinding. 31P MAS NMR spectra