Epoxidation of monomaleate with hydrogen peroxide catalyzed by [π-C 5H5N(CH2)15CH3] 3PO4(WO3)4

Article abstract of DOI:10.1080/00397911.2010.518277

In the study, epoxidation of dodecanol monomaleate, hexadecanol monomaleate, and octadecanol monomaleate were carried out using [π-C ₅H₅N(CH₂)₁₅CH₃] ₃PO₄(WO₃)₄ as phase-transfer catalyst with 30% hydrogen peroxide as oxidant. The experimental results showed that [π-C₅H₅N(CH₂)₁₅CH ₃]₃PO₄(WO₃)₄ had excellent catalytic effect on translating C=C double-bond into an epoxy group and had a good yield rate. The synthesized epoxides of decanol monomaleate, hexadecanol monomaleate, and octadecanol monomaleate have enormous potential application in organic synthesis, and they could be readily transformed into various synthetically useful intermediates or final products in many fields of chemistry.

Full text of DOI:10.1080/00397911.2010.518277

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Epoxidation of Monomaleate with
Hydrogen Peroxide Catalyzed by [π-
C H N(CH ) CH ] PO (WO )
5
5
2 15
3 3
4
3 4
a
a
Zhiliang Zhang & Tianduo Li
a
Research Center of Analysis and Testing, Shandong Institute of
Light Industry, Jinan, China
Published online: 26 Jul 2011.
To cite this article: Zhiliang Zhang & Tianduo Li (2011) Epoxidation of Monomaleate with
Hydrogen Peroxide Catalyzed by [π-C H N(CH ) CH ] PO (WO ) , Synthetic Communications: An
5
5
2 15
3 3
4
3 4
International Journal for Rapid Communication of Synthetic Organic Chemistry, 41:22, 3417-3423,
DOI: 10.1080/00397911.2010.518277
To link to this article: http://dx.doi.org/10.1080/00397911.2010.518277
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1
Synthetic Communications , 41: 3417–3423, 2011
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.518277
EPOXIDATION OF MONOMALEATE WITH
HYDROGEN PEROXIDE CATALYZED BY
p-C H N(CH ) CH ] PO (WO )
[
5
5
2 15
3 3
4
3 4
Zhiliang Zhang and Tianduo Li
Research Center of Analysis and Testing, Shandong Institute of Light
Industry, Jinan, China
GRAPHICAL ABSTRACT
Abstract In the study, epoxidation of dodecanol monomaleate, hexadecanol monomaleate,
and octadecanol monomaleate were carried out using [p-C
WO as phase-transfer catalyst with 30% hydrogen peroxide as oxidant. The experi-
mental results showed that [p-C N(CH 15CH PO (WO had excellent catalytic
5 5 2 3 3 4
H N(CH )15CH ] PO
(
3 4
)
5
H
5
2
)
]
3 3
4
3 4
)
effect on translating C=C double-bond into an epoxy group and had a good yield rate.
The synthesized epoxides of decanol monomaleate, hexadecanol monomaleate, and octa-
decanol monomaleate have enormous potential application in organic synthesis, and they
could be readily transformed into various synthetically useful intermediates or final products
in many fields of chemistry.
Keywords Epoxidation; monomaleate; phase-transfer catalyst
Received May 18, 2010.
Address correspondence to Zhiliang Zhang, Research Center of Analysis and Testing, Shandong
Institute of Light Industry, Jinan 250353, China. E-mail: zhzhl5686@163.com
3
417

3418
Z. ZHANG AND T. LI
INTRODUCTION
Epoxide compounds, especially,a,b-unsaturated carbonyl epoxidized com-
pounds, have become some of the most significant organic chemicals, not only
because the resulting epoxy compounds could be directly used in organic synthesis
as essential building blocks but also because they could be readily transformed into
various synthetically useful intermediates for both laboratory and industry in a wide
[
1–3]
range of fields within chemistry.
sizes developing new, effective methodologies that can epoxize a series of carbonyl
The research in recent years particularly empha-
[
4–8]
compounds with the C=C double bond and advance the yields.
As an a,b-unsaturated carbonyl compound derivative, monomaleate is electron
deficient because of the electron-withdrawing substituents adjacent to the C=C dou-
ble bond, so it is difficult to epoxidize them using electron-rich olefins, generally
[
9–15]
achieved with polyoxometalates.
and W(VI)] complexes bring about epoxidation through metal–hydroperoxide com-
In these cases, transitional-metal [V(V), Mo(VI),
[
plexes, whereas aqueous hydrogen peroxide epoxidizes in the presence of tungstate
or molybdate through peroxy acid. At the same time, it is also impossible to epox-
[
idize monomaleate with aqueous a,b-unsaturated carbonyl compound,
16]
[17]
18–23]
because
monomaleate is immiscible with aqueous oxidant phase, especially when it has long
carbon chain, such as decanol monomaleate, hexadecanol monomaleate, and octa-
decanol monomaleate.
According to a review of the literature available to us, no research articles or
investigation of epoxidation of decanol monomaleate, hexadecanol monomaleate,
or octadecanol monomaleate have been reported. This article presents an effective
epoxidation method of decanol monomaleate, hexadecanol monomaleate, and
octadecanol monomaleate with H O as green oxidant catalyzed by phase-transfer
2
2
catalyst [p-C H N(CH ) CH ] PO (WO ) .
5
5
2 15
3 3
4
3 4
RESULTS AND DISCUSSION
Phase-transfer catalysis is a technique by which reactions between substances
located in mutually immiscible phases are brought about or accelerated. In compari-
son with traditional methods, phase-transfer catalysis has the following advantages:
no need for expensive aprotic solvent, simpler workup, shorter reaction time, and
lower reaction temperature. In the study, a phase-transfer catalyst, Q PO (WO )
3 4
3
4
þ
(
Q ¼ [p-C H N(CH ) CH ] ), was synthesized according to Scheme 1, which was
5
5
2 15
3
[24–26]
similar to methods given in the literature.
The syntheses of monomaleates 2a–c were carried out according to the proto-
col described in Scheme 2 by the esterification of maleic acid with the corresponding
decanol, hexadecanol, and octadecanol respectively and heating the solution of the
ꢀ
reactants at 82 C. No solvents were needed to prepare the monomaleates 2a–c.
3 4 3 4
Scheme 1. Synthesis of Q PO (WO ) .

EPOXIDATION OF MONOMALEATE
3419
Scheme 2. Epoxidation of decanol monomaleate, hexadecanol monomaleate, and octadecanol monomaleate.
The use of hydrogen peroxide as oxidant in epoxidation was attractive both from
environmental and economical standpoints. It was cheap and readily available and
gave water as the only by-product.
Decanol monomaleate, hexadecanol monomaleate, and octadecanol mono-
maleate were epoxidized according to the protocol described in Scheme 2. To obtain
the basic information regarding the optimum reaction conditions, decanol mono-
maleate was attempted first as a model compound under the various reaction con-
ditions, and the results are summarized in Table 1.
As shown in Table 1, the pH of solution had a significant effect on the epox-
idation. Monomaleate (2a, 1 mmol) was reacted with H O (1.5 mmol) under
2
2
0.005 mol equivalent Q PO (WO ) catalyst. When pH was 4.0 (entry 1–3), the best
3 4 3 4
yield of 3a was 46% (entry 2); when pH was 5.0 (entry 4–6), the best yield of 3a was
6
8
7% (entry 5); and when pH was 6.0 (entry 7–9), the best yield of 3a was 52% (entry
). The reason was possibly that the Q PO (WO ) had better catalytic effect when
3
4
3 4
the pH of solution was 5.0. The influence of temperature on the reaction was also
investigated. When increasing the temperature at the very start, the yield also
Table 1. Effect of reaction condition on epoxidation of monomaleate (2a) with H
PO (WO
O
2 2
catalyzed by
Yield (%)
Q
3
4
3 4
)
ꢀ
Entry
pH
Temperature ( C)
Reaction time (h)
1
2
3
4
5
6
7
8
9
4.0
4.0
4.0
5.0
5.0
5.0
6.0
6.0
6.0
50
60
70
50
60
70
50
60
70
2
3
4
4
2
3
3
4
2
32
46
38
51
67
48
43
52
42

3420
Z. ZHANG AND T. LI
Table 2. Epoxidation of monomaleate (2a–3c) with H
2
O
2
3 4 3 4
catalyzed by Q PO (WO )
Entry
Substrate (mmol)
H
O
2 2
(mmol)
Q
3
PW 16 (mmol)
4
O
Yield (%)
1
2
3
2a
2b
2c
1.5
0.005
0.005
0.005
67
63
61
1.5
1.5
ꢀ
Note: Reaction condition: pH 5.0, 60 C, reation time 2 h, and the amount of 2a–c was 1.0 mmol respec-
tively.
increased. With further increase of temperature, the yield would decreased. For
ꢀ
example, when temperature was 50 C, the epoxidation of 2a was carried out in
ꢀ
3
5
2% yield (entry 1); when the temperature increased to 60 C, the yield of 3a was
ꢀ
1% (entry 4); and when temperature was 70 C, the yield of 3a decreased to 43%
(entry 7). This was because epoxidation of decanol monomaleate was not easy to
carry out at a lower temperature, and at the same time the epoxy group was unstable
and easy to decompose at the higher temperatures. The reaction time had little effect
on the reaction, and the proper reaction time was 2 h. We also did experiments in the
absence of Q PO (WO ) catalyst, and no yield was obtained at the same reaction
3
4
3 4
conditions. It was apparent that the Q PO (WO ) catalyst played a critical role dur-
3 4
3
4
ing the reaction of 2a to 3a.
From these results, the reaction conditions we chose were as follows: decanol
monomaleate (2a, 1 mmol), hydrogen peroxide (30%, 1.5 mmol), Q PO (WO ) cata-
3
4
3 4
ꢀ
lyst (0.005 mmol), pH 5.0, 60 C, and reation time 2 h. Using this reaction system, we
did a series of experiments for the epoxidation of monomaleate (2a–c). The results
are summarized in Table 2.
In summary, this was the first time epoxidation of dodecanol monomaleate,
hexadecanol monomaleate, and octadecanol monomaleate was carried out using
Q PO (WO ) as catalyst with H O as green oxidant, and the research indicated
3
4
3 4
2
2
that Q PO (WO ) had an excellent catalytic effect on translating the C=C double
3
4
3 4
bonds of the monomaleates into epoxy groups. This method was a useful and
attractive process for the epoxidation of monomaleates with long carbon chains in
a single-step operation.
EXPERIMENTAL
Maleic anhydride, dodecanol, hexadecanol, and octadecanol were from Tianjin
Kemiou Chemical Co., Ltd. Sodium tungstate and hydrogen peroxide (30 wt%) were
purchased from Chinese Medical Group (Shanghai Medicament Co., Ltd.). Tungstic
acid (37 wt%), phosphoric acid, and dichloromethane were all obtained from Tianjin
Dacheng Chemical Co., Ltd.). The other chemicals were analytical or high-reagent
grade.
ꢁ1
Fourier transform infrared (FTIR) spectra in the range of 400–4000 cm were
recorded on a FTIR Tensor 27 instrument (Bruker, Germany). KBr pellets were used
1
for sample preparation. H NMR spectra were collected on a Bruker AV400 spec-
trometer (Bruker AXS, Germany) using CD Cl as solvent and and tetramethylsilane
3
(
TMS, d ¼ 0 ppm) as internal standard. Elemental analyses were performed on a
Vario EL III (Elmentar, Germany).

EPOXIDATION OF MONOMALEATE
3421
Synthesis of [p-C H N(CH ) CH ] PO (WO ) Phase-Transfer
5
5
2 15
3 3
4
3 4
Catalyst
A suspension of tungstic acid (10 mmol) in 10 ml of 30% aqueous H O was
2
2
ꢀ
heated to 60 C and stirred for 60 min. To the obtained colorless solution, at room
temperature, 85% H PO (2.5 mmol) dissolved in 1 ml of water was added, and the
3
4
whole was diluted with another 20 ml of water and then stirred for 30 min. To the
resultant solution, cetylpyridiniumammonium chloride (5 mmol) in dichloromethane
(40 ml) was added dropwise with stirring over about 2 min. Stirring was continued
for an additional 60 min. The organic phase was then separated, dried over Na SO ,
2
4
ꢀ
filtered, and distilled at 50–60 C (water bath) at atmospheric pressure. The dried
yellow powder (85.0% yield by weight based on the quaternary ammonium salt
charged) was obtained by further evaporation under reduced pressure.
Synthesis of Monomaleate 2a–c
Dodecanol (0.1 mol) was added to a four-necked flask equipped a thermometer
ꢀ
and a magnetic stirrer and heated to 82 C. Maleic anhydride (0.11 mol) were added
ꢀ
slowly into the flask. The reactants were maintained at 82 C for 2 h. The unreacted
ꢀ
maleic anhydride was removed by washing at 80 C. After washing, the product was
ꢀ
kept at 35 C under vacuum drying for 10 h, and dried white powder (96%) was
obtained. A similar procedure was employed for the syntheses of hexadecanol mono-
maleate and octadecanol monomaleate.
Synthesis of Monomaleate Epoxide 3a–c
Dodecanol monomaleate (20 mmol), Q PO (WO ) (0.1 mmol), and 10 mL
3
4
3 4
deionized water were added to a four-necked flask equipped with a thermometer
ꢀ
and stirred for 30 min at 50 C. Hydrogen peroxide (3.6 mL) was added to the mix-
ꢀ
ꢀ
ture during 30 min at 50 C, and the temperature slowly rose to 60 C. After the mix-
ꢀ
ture was reacted for 3 h at 60 C and the impurities were removed, the epoxides of
dodecanol monomaleate were obtained. A similar procedure was employed for the
epoxidation of hexadecanol monomaleate and octadecanol monomaleate.
Data
ꢁ1
[
468, 721 (CH –(CH ) -); 1581, 1502, 1436 (pyridine vibration); 1077 (P-O); 941
p-C H N(CH ) CH ] PO (WO ) . IR (KBr, n, cm ): 2960, 2920, 2852,
5
5
2 15
3 3
4
3 4
1
3 2 15
(
W=O); 882, 816 (W-O-W); 836 (-O-). Elemental analysis calcd. for Q PO (WO )
3 4 3 4
(%): C, 39.08; H, 5.95; N, 2.17. Found: C, 38.12; H, 6.08; N, 2.46. Determination
of active oxygen showed that no peroxo bridge existed in the molecule.
ꢁ
1
Dodecanol monomaleate 2a. IR (KBr, n, cm ): 3560 (-OH); 2956, 2922,
2
(
852, 1460, 1360 (CH –(CH ) -); 1724, 1706 (-C=O); 1648 (C=C), 1217, 1167
3
2 11
1
-C-O-). H NMR (400 MHz, CDCl , ppm): 6.398 (d, 1H, -HC=CH-C=O); 6.325
3
(
d, 1H, -HC=CH-C=O); 4.218 (m, 2H, -O-CH -CH -); 1.652 (m, 2H, -O-CH -
2
2
2
CH -); 1.192 (m, 18H, -(CH ) -), 0.826 (m, 3H, -CH ).
2
2 9
3
ꢁ
1
Hexadecanol monomaleate 2b. IR (KBr, n, cm ): 3520 (-OH); 2952, 2910,
852, 1450, 1362 (CH –(CH ) -); 1726, 1702 (-C=O); 1642 (C=C), 1215, 1152
2
3
2 15

3422
Z. ZHANG AND T. LI
1
(
-C-O-). H NMR (400 MHz, CDCl , ppm): 6.402 (d, 1H, -HC=CH-C=O); 6.336 (d,
3
1
1
H, -HC=CH-C=O); 4.226 (m, 2H, -O-CH -CH -); 1.662 (m, 2H, -O-CH -CH -);
2
2
2
2
.195 (m, 26H, -(CH ) -); 0.830 (m, 3H, -CH ).
2
13
3
ꢁ
1
Octadecanol monomaleate 2c. IR (KBr, n, cm ): 3556 (-OH); 2952, 2920,
2
836, 1450, 1356 (CH –(CH ) -); 1722, 1712 (-C=O); 1646 (C=C), 1208, 1152 (-C-
3
2 17
1
O-). H NMR (400 MHz, CDCl , ppm): 6.412 (d, 1H, -HC=CH-C=O); 6.365 (d, 1H,
3
-
HC=CH-C=O); 4.236 (m, 2H, -O-CH -CH -); 1.668 (m, 2H, -O-CH -CH -); 1.121
2
2
2
2
(
m, 30H, -(CH ) -); 0.836 (m, 3H, -CH ).
2
15
3
ꢁ
1
Epoxide of dodecanol monomaleate 3a. IR (KBr, n, cm ): 3562 (-OH);
2
O-); 1050 (-C-O-C). H NMR (400 MHz, CDCl , ppm) 4.276 (m 2H, -O-CH -
952, 2916, 2850, 1462, 1366 (CH –(CH ) -); 1726, 1702 (-C=O); 1220, 1165 (-C-
3
2 11
1
3
2
CH -); 1.748 (m, 2H, -O-CH -CH -); 1.326 (m, 18H, -(CH ) -); 0.906 (m, 3H, -
2
2
2
2 9
CH ); 3.808 (d, 2H, H of epoxy group), 3.765 (d, 2H, H of epoxy group).
3
ꢁ1
Epoxide of hexadecanol monomaleate 3b. IR (KBr, n, cm ): 3552
(
-OH); 2956, 2912, 2842, 1458, 1346 (CH –(CH ) -); 1728, 1704 (-C=O); 1226,
3
2 11
1
1
170 (-C-O-); 1046 (-C-O-C). H NMR (400 MHz, CDCl , ppm) 4.265 (m, 2H,
3
-
(
O-CH -CH -); 1.732 (m, 2H, -O-CH -CH -); 1.332 (m, 26H, -(CH ) -); 0.912
2 2 2 2 2 13
m, 3H, -CH ); 3.825 (d, 2H, H of epoxy group), 3.726 (d, 2H, H of epoxy group).
3
ꢁ1
Epoxide of octadecanol monomaleate 3c. IR (KBr, n, cm ): 3556 (-OH);
2
1
1
3
962, 2912, 2842, 1460, 1362 (CH –(CH ) -); 1728, 1706 (-C=O); 1220, 1166 (-C-O-);
3
2 11
1
052 (-C-O-C). H NMR (400 MHz, CDCl , ppm) 4.268 (m, 2H, -O-CH -CH -);
3
2
2
.742 (m, 2H, -O-CH -CH -); 1.322 (m, 30H, -(CH ) -); 0.916 (m, 3H, -CH );
3
2
2
2 15
.832 (d, 2H, H of epoxy group), 3.772 (d, 2H, H of epoxy group).
ACKNOWLEDGMENT
Financial support from the Shandong Province Municipal Major Science and
Technology Special Project (2006GG1108097-10) is gratefully acknowledged.
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