A green protocol for synthesis of methylene dioximes promoted by an ionic liquid [bmim]BF4

Article abstract of DOI:10.3184/030823409X466735

The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim]BF₄, has been demonstrated to be an effective catalyst for synthesis of methylene dioximes. These reactions proceed with excellent yields under shorter reaction times than ot

Full text of DOI:10.3184/030823409X466735

Journal of Chemical Research
2009
ISSN 0308-2342
Issue No. 8
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Contents
ReseaRch PaPeRs
O
473
Ionic liquid promoted and mediated green
preparation of arylbispyranylmethane and
pyran derivatives and their hybrid with a
pyrimidine nucleoside
OAc
HN
N
O
O
O
O
OAc
O
N
O
O
CHO
O
HN
OH OH
O
[bmim]BF4
OH
O
2
O
+
Xinying Zhang, Yingying Qu, Xuesen Fan,
Xia Wang and Jianji Wang
AcO
O
OAc
HN
N
O
(CH3CO)2O
OAc
O
O
O
OAc
O
O
O
478
482
485
489
Iron-catalysed Sonogashira reactions
Fe(acac)3 / L1
Ar1
Ar2
Ar2
I
Ar1
H
Cs2CO3, toluene,135 o
C
Changduo Pan, Fang Luo, Wenhui Wang,
Zhishi Ye and Miaochang Liu
N
N
An efficient synthesis of (+/-) cherylline
dimethyl ether
O
O
O
O
O
CN
N
A.Sanjeev Kumar, Samir Ghosh, Kale Bhima and
G.N. Mehta
O
An efficient synthesis of phenyl-substituted
dibenzonaphthyridines
R
Cl
N
R = R' = H
R = CH3, R' = H
R = H, R' = CH3
R = Cl, R' = H
R'
Ph
N
CH3
Manickam Manoj and Karnam Jayaramapillai
Rajendra Prasad
Addition–cyclisation of 3-(2-thienyl)acryloyl
isothiocyanate with hydrazine derivatives as
a source of triazoles and thiadiazoles
O
CH=CH
S
N=C=S
Magdy M. Hemdan
JCR_08_2009 Book.indb
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CONTENTS
492
n
Synthesis, characterisation and luminescence
properties of novel Eu(TTA)3−co-polymer and
Tb(TPC)3−co-polymer
m
N
N
N
O
(Ligand)3
Re
Siqing Wang, Hui Cang, Wenzhong Yang and
Jintang Wang
RE-co-polymer
495
499
505
508
511
515
Synthesis of spiro(cyclohexa-diene-pyrazolo
[1,5-a]pyrimidine-4-ylidene)-malononitrile
derivatives
Ar
N
H2N
CN
CN
NH
N
CN
H2N
6
Yusria R. Ibrahim
Proline triflate catalysed Diels–Alder reaction in
the synthesis of tetrahydroquinoline derivatives
H
H
CHO
R
NH2
O
O
Proline triflate ( 5 mol%)
25 oC, CH3CN
+
+
NH
R= o-OH or m-OCH3
R= m-NO2 or p-OCH3
cis- 100%
trans- 100%
R
Jianjun Li, Jia Li and Weike Su
In situ halo-aldol reaction of aldehydes with
cyclopropyl ketone promoted by MgI2 etherate
O
O
OH
MgI2 (OEt2)n
CH2Cl2, r.t.
RCHO
+
H3C
H3C
R
I
Xingxian Zhang
Facile synthesis of amide and
amine derivatives of
2,2,3,3-tetramethylcyclopropanecarboxylic acid
R2
N
R1
Hui-Long Wang, Wen-Feng Jiang and Zhe-Qi Li
Synthesis, characterisation, cytotoxicity and
radioprotective effect of novel chiral nitronyl
nitroxyl radicals
O
O
N
N
N
O
N
N
O
O
N
O
Boc
Boc
Xiang-Yang Qin, Gui-Rong Ding, Xiao-Wu Wang,
Juan Tan, Guo-Zhen Guo and Xiao-Li Sun
L-NNVP
L-NNP
6
6
9
9
Synthesis and conformational studies
of 9-methoxy- and 9-methyl-
2,11-dithia[3.3]metacyclophanes
R
R
OMe
Me
S
S
S
15
tBu 15
tBu
S
R= H, tBu
anti-conformation
R= H, Me, Et. tBu, Br
syn-conformation
Tomoe Shimizu, Takayuki Maeda, Katsuhiro Hida
and Takehiko Yamato
JC0809_Contents.indd
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10/8/09 12:10:01

CONTENTS
520
Cu(OTf)2-catalysed synthesis of structurally
novel bicyclic 1,3-oxazines via condensation-
dehydrazinative ring transformation cascades
Ph
HO
N
O(S)
O
(CHOH)n-2
3
CH2OH
Lal Dhar Singh Yadav, Ankita Rai, Vijai Kumar Rai
and Chhama Awasthi
527
Synthesis, characterisation and activity in
catalytic epoxidation of olefins of new dinuclear
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Manindranath Bera
Innovations for
Journal of
Chemical Research
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J. Eames and N. Weerasooriya, Recent Studies on the regioselective C-protonation of enol derivatives using carbonyl-containing
proton donors. J. Chem. Research (S), 2001, 2-8.
J.R. Hanson, A.J.M. Sanchez and C. Uyanik, Applications of tetracyanoethylene as a p-acid catalyst. J. Chem. Research (S), 2001, 121-123.
K. Hemming, Recent developments in the synthesis, chemistry, and applications of the fully unsaturated 1,2,4-oxadiazoles. J. Chem. Research (S),
2001, 209-216.
A.G. Davies, The generation of organic radical cations: a guide to current practice for EPR spectroscopic studies. J. Chem. Research (S), 2001,
253-261.
D.J. Evans, Metal-sulfur chemistry with a view to modelling the active sites of some enzymes of environmental importance. J. Chem. Research (S), 2001,
297-303.
L.J. Twyman and A.S.H. King, Catalysis using peripherally functionalized dendrimers J. Chem. Research (S), 2002, 43-59.
R.L. Richards and M.C. Durrant, Copper complexes with N-donor ligands as models of the active centres of nitrite reductase and
related enzymes. J. Chem. Research (S), 2002, 95-98.
T. Thiemann and K.G. Dongol, Thiophene S-oxides. J. Chem. Research (S), 2002, 303-308.
R.A. Henderson, Protonation mechanisms of nickel complexes relevant to industrial and biological catalysis. J. Chem. Research (S), 407-411.
W. Levason and G. Reid, Early transition metal complexes of polydentate and marcrocyclic thio- and seleno-ethers. J. Chem. Research (S), 2002, 1-5.
J.R. Hanson, Directing effects in the hydroboration of steroidal alkenes. J. Chem. Research, 2004, 1-5.
Z.V. Todres, Recent advances in the study of mechanochromic transitions of organic compounds. J. Chem. Research, 2004, 89-93.
S. Ghosh, Recent research and development in synthetic polymer-based drug delivery systems. J. Chem. Research, 2004, 241-246.
A.G. Davies, Difunctional distannoxanes. J. Chem. Research, 2004, 241-246
J.A.R. Salvador and J.R. Hanson, Solid phase oxidation of steroidal alkenes with potassium permanganate and metal salts. J. Chem. Research, 2004,
513-516
K. Hemming and C. Loukou, Synthetic approaches to 1,2,5-benzothiadiazepine 1,1-dioxides: sulphonamide analogues of 1,4-benzodiazepines. J. Chem.
Research, 2005, 1-12.
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N.L. Lancaster, Organic reactivity in ionic liquids: some mechanistic insights into nucleophiloic substitution reactions. J. Chem. Research, 2005, 413-417.
A.G. Davies, Recent advances in the chemistry of the organotin hydrides. J. Chem. Research, 2006, 141-148.
Goreti Ribeiro Morais, Masataka Watanabe, Masao Imai, Naho Yoshioka, Tomohiro Matsumoto, Shuntaro Mataka and Thies Thiemann, Ring D
16,17–heteroannelated estranes. J.Chem. Research, 2006, 617-622.
Simón E. López, Jelem Restrepo and José Salazar, Polyphosphoric acid trimethylsilylester: a useful reagent for organic synthesis. J.Chem. Research,
2007, 497-502.
Dennis N. Kevill and Malcolm J. D’Souza, Sixty years of the Grunwald–Winstein equation: development and recent applications. J.Chem. Research,
2008, 61-66.
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JCR_08_2009 Book.indb
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JOURNAL OF CHEMICAL RESEARCH 2009
AUGUST, 465–467
RESEARCH PAPER 465
A green protocol for synthesis of methylene dioximes promoted by an
ionic liquid [bmim]BF4
Hongjun Zang*, Yong Zhang, Meiling Wang and Bo-Wen Cheng
Department of Material Science and Chemistry Engineering, Tianjin Polytechnic University, Tianjin Municipal Key Laboratory of
Fiber Modification and Functional Fiber, Tianjin 300160, P.R. China
The ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim]BF4, has been demonstrated to be an effective
catalyst for synthesis of methylene dioximes. These reactions proceed with excellent yields under shorter reaction
times than other reported methods. Furthermore, the ionic liquid [bmim]BF4 can be recycled and reused without
loss of catalytic activity.
Keywords: methylene dioximes, phase transfer catalyst, ionic liquid
In recent years, room-temperature ionic liquids (RTILs),
new types of solvent for green chemistry, have been studied
because they are stable, nonvolatile, and easy to recycle. Many
important reactions have been carried out in ionic liquids.1-5
Although many types of reactions have been investigated in
ionic liquids, only a few examples of nucleophilic substitution
reactions have been reported.6-9 Nucleophilic displacement
reactions are often carried out using phase transfer catalysts
(PTC) to facilitate the reaction between the organic reactants
and the inorganic ionic salts that provide the nucleophiles.10
We envisaged the use of ionic liquids as catalysts would be
advantageous in such a reaction as the synthesis of methylene
dioximes.
Methylene dioximes are important chemicals useful as
metal capturers, and anti-inflammatory and antibacterial
agents.11 The main synthetic route involves the use of phase
transfer catalysts (PTCs) in the heterogenous reaction between
oximes and dichloromethane. The synthesis of methylene
dioximes involves alkylation of oximes with dichloromethane
using either: (1) quaternary ammonium salt with 50%
aqueous solutions of sodium hydroxide for 16 h,12 (2) sodium
hydroxide in combination with tetrabutylammonium bromide
for 20 h,13 (3) potassium superoxide in the presence of di-μ-
chlorobis (2-methylallyl) dipalladium (II) catalyst for 72 h,14,15
(4) potassium carbonate in combination with 18-crown-
6 for 12 h under argon at 50°C,15 (5) sodium hydroxide in
the presence of a low-molecular weight polyethylene glycol-
400 (PEG-400) for 14–20 h,16 (6) potassium hydroxide in
combination with 18-crown-6 in acetonitrile at 70°C,17 (7)
and sodium hydroxide in the presence of benzyldimethyl-
tetradecylammonium chloride for 2–3.5 h.18 However, some
of these methods have not been entirely satisfactory, with
disadvantages such as relatively long reaction times, low
yield, high reaction temperature and using a catalyst that
cannot be recycled. Therefore, the development of a simple,
efficient, and environmentally benign method for the synthesis
of methylene dioximes remains desirable.
for the preparation of methylene dioximes using ionic liquids
as a substitute for phase transfer catalysis methods.
In our initial research, acetophenone oximes were selected
as a representative reactant in order to optimise the reaction
conditions. Reactions were carried out in different ionic
liquids at room temperature under stirring. As shown in
Table 1, the reaction proceeded efficiently in the ionic liquids
[bmim]Br, [bmim]BF4, [bmim]OH, [amim]Cl and [bmim]PF6.
The best reaction performance was delivered by [bmim]BF4
(Table 1, Entry 3), which provided the product 3a in 96%
yield in 30 min. Whereas in other reported methods,12-18
to obtain the same yield needed 3.5 h. It was clear that
synthesis of methylene dioximes using the ionic liquid as a
catalyst was a quick and effective method. So [bmim]BF4 was
chosen for further study in this work.
Effects of reaction time on the yields of the products were
also studied by prolonging the reaction time. When the
reaction time was prolonged to 60 min, the compound 3a
(entries 2, 6, 8 and 10) was obtained in nearly 95% yield with
different ionic liquids. The results showed that the reactions
could proceed more efficiently with a prolonged reaction
time.
Table
1 The reaction of acetophenone oxime with
dichloromethane in different ionic liquids at room temperature
under stirring
Entrya
RTIL
Time/min
Yield/%b
1
2
[bmim]Br
[bmim]Br
[bmim]BF4
[bmim]BF4
[bmim]OH
[bmim]OH
[amim]Cl
[amim]Cl
[bmim]PF6
[bmim]PF6
30
60
30
30
30
60
30
60
30
60
87
94
96
94c
89
93
91
95
84
93
3
4
5
6
7
8
9
10
aReaction conditions: 0.5 mmol acetophenone oxime, 3.5 mL
dichloromethane, 0.1 mmol ionic liquid, 4 mmol sodium hydroxide
bIsolated yield.
As a continuation of our endeavours in green synthesis and
using ionic liquids as a recyclable, eco-friendly catalysts,19 we
report here an efficient and environmentally friendly procedure
c[bmim]BF4 was reused.
R1
R1
[bmim]BF4
CH2
CH2Cl2
C
N
O
C
N
OH
+
NaOH
R2
R2
2
1
2
3
Scheme 1
* Correspondent. E-mail: zanghongjun@tjpu.edu.cn
PAPER: 09/0462

466 JOURNAL OF CHEMICAL RESEARCH 2009
Table 2 Synthesis of methylene dioximes by [bmim]BF4 with different alkalies
Entry
Time/min
Alkali
Yield/%a
1
2
3
4
5
6
7
8
9
30
30
120
30
120
30
120
30
NaOH
K2CO3
K2CO3
Na2CO3
Na2CO3
CH3COONa
CH3COONa
None
96
0
0
0
0
10
30
0
120
None
0
aIsolated yield.
Since the recovery and reuse of catalyst and solvent are
highly preferable for a green process, we next investigated the
reusability and recycling of the ionic liquid. After completion
of the reaction, water was added into the reaction mixture, and
the mixture was extracted by CH2Cl2. The water containing
[bmim]BF4 was evaporated under reduced pressure to
recover the ionic liquid. The recycled [bmim]BF4 (Table 1,
entry 4) was reused in the reaction of acetophenone oxime
with dichloromethane. The catalytic activity of did not show
any significant decrease.
Simultaneously, the reaction of acetophenone oxime
with dichloromethane was also performed in the presence
of different alkalis such as NaOH, K2CO3, Na2CO3, CH3COONa
or without alkali in [bmim]BF4 under the same reaction
conditions (Table 2). The result showed that the reaction could
not occur in the presence of potassium carbonate and sodium
carbonate (Table 2, entries 2–5). Though in the presence of
sodium acetate methylene dioximes could be obtained, the yield
(only 10% and 30%) was lower than with sodium hydroxide
(Table 2, entry 1). As shown in the Table 2 (entries 8, 9), the
reaction did not occur without alkali. It showed that only in
alkaline conditions, the reaction could be carried out. In the
presence of strong base, the reaction was more easily carried out
than with the weak base. These results revealed that [bmim]BF4
combined with NaOH could effectively accelerate the reaction
at room temperature under stirring.
With these results in hand, we turned our attention
to the scope of the oximes in the reaction. The results
were summarised in Table 3. For most of substrates, the
reaction was completed at 20–30 min with high yields.
whereas in reported methods,12-18 the reaction was completed
to need not less than 2 h with similar or lower yields. For
example, compound 3e was previously prepared in 90%
yield within 3.5 h under ultrasonication,18 whereas in the
presence of [bmim]BF4, 3e was obtained in 93% yield in
30 min. The yield of 3e was increased and the reaction time
was shortened.
Experimental
Materials and instruments
Melting points were recorded on an electrothermal apparatus and
were uncorrected. The 1H NMR and 13C NMR spectra were measured
on a Bruker AVANCE 300 spectrometer using TMS as internal
standard and CDCl3 as solvent. IR spectra were measured with a
BIO-RAD FTS3000 spectrometer. Mass spectra were obtained in
ESI mode using a BrukerEsquire 3000 mass spectrometer. Elemental
analyses were obtained using a Perkin–Elmer auto-analyser.
General procedure for the preparation of methylene dioximes
Theoxime(1,0.5mmol)wasdissolvedindichloromethane(2,3.5mL).
[bmim]BF4 (0.227g,0.1mmol)andsodiumhydroxidepowder(0.160g,
4
mmol) were added. The reaction mixture was stirred at
room temperature for 30 min. The mixture was washed with water
(10 mL) and extracted with CH2Cl2 (3.15 mL). The combined
organic layers were dried over anhydrous sodium sulfate, filtered,
and evaporated to dryness in vacuo. The product was purified by
chromatography on silica (200–300 mesh). Elution with a mixture
of petroleum ether and ethyl acetate (20/1, V/V) afforded the
methylene dioximes 3a–j. All the known products 3a–g, 3j were fully
1
characterised by IR and H NMR spectroscopy, and melting points,
which were consistent with the literature data. The new compounds
3h–i were identified by IR,1H NMR, 13C NMR, MS spectroscopy and
elemental analysis.
3h: White solid; m.p. 162–164°C. nmax (KBr)/cm−1 3417, 3053,
2941, 1649, 1518, 1044, 832. 1H NMR (300 MHz, CDCl3) 2.21
(s, 6H, CH3), 3.80 (brs, 4H, NH2), 5.80 (s, 2H, CH2), 6.65 (d, J = 8.9 Hz,
4H, ArH), 7.51(d, J = 8.9 Hz, 4H, ArH). 13C NMR (300 MHz, CDCl3)
156.9, 147.8, 127.8, 126.9, 114.8, 99.2, 13.3. MS: m/z 335 [M + Na]+,
313 [M + 1]+. Anal. Calcd for C17H20N4O2: C 65.38, H 6.41, N 17.95.
Found C 65.35, H 6.43, N 17.99%.
3i: White solid; m.p. 144–146°C. nmax (KBr)/cm−1 3324, 2961,
1
1638, 1502, 1125, 811. H NMR (300 MHz, CDCl3) 2.99 (s, 12H,
CH3), 5.72 (s, 2H, CH2), 6.68 (d, 4H, J = 8.9 Hz, ArH), 7.49 (d, 4H,
J = 8.9 Hz, ArH), 8.12 (s, 2H, N=CH). 13C NMR (300 MHz, CDCl3)
151.6, 151.4, 128.7, 119.4, 111.7, 99.1, 40.2. MS: m/z 363 [M + Na]+,
341 [M + 1]+. Anal. Calcd for C19H24N4O2: C 67.06, H 7.06, N 16.47.
Found C 67.03, H 7.08, N 16.46%.
The project was supported by the Tianjin National Natural
Science Foundation (No. 07JCYBJC02200).
Table 3 Synthesis of methylene dioximes in ionic liquid [bmim]BF4 in presence of NaOH
Entry
Oximes
Time/min
Yielda/%
M.p./°C (lit.)
R1
R2
3a
3b
3c
3d
3e
3f
Ph
Ph
Me
Ph
30
20
30
30
30
20
30
30
30
20
96
99
87
78
93
97
81
94
92
97
95–97(94–96)15
81–83(81–83)15
41–43(44–46)15
52–54(56–58)15
142–144(136–138)15
147–150(158–160)15
42–44(44)14
—(CH2)5—
—(CH2)4—
4-MeOC6H4
4-O2NC6H4
Me
4-H2NC6H4
4-(CH3)2NC6H4
2-MeOC6H4
Me
Me
Me
Me
H
3g
3h
3i
162–164
144–146
3j
H
91–94(98–99)15
aIsolated yield.
PAPER: 09/0462

JOURNAL OF CHEMICAL RESEARCH 2009 467
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Received 24 February 2009; accepted 8 June 2009
Paper 09/0462 doi: 10.3184/030823409X466735
Published online: 14 August 2009
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