Synthesis of polynitrostilbenes from 2,4,6-trinitro-m-xylene and 2,4,6-trinitrotoluene by a microwave-assisted solvent free method

Article abstract of DOI:10.3184/174751914X13944453321075

A microwave-assisted method for the synthesis of polynitrostilbenes involving the condensation of 2,4,6-trinitro-m-xylene and 2,4,6-trinitrotoluene with aryl aldehydes in the presence of piperidine and silica-gel is reported. Compared with conventional methods, a shorter reaction time is required and this method has a lower environmental impact. A mechanism for the reaction is also proposed and supported by UV-Vis absorption spectroscopy.

Full text of DOI:10.3184/174751914X13944453321075

240 RESEARCH PAPER
VOL. 38 APRIL, 240–244
JOURNAL OF CHEMICAL RESEARCH 2014
Synthesis of polynitrostilbenes from 2,4,6-trinitro-m-xylene and
2,4,6-trinitrotoluene by a microwave-assisted solvent free method
Junhui Xua, Fangmei Lia, Jianping Weia and Xinhua Penga*
School of Chemical Engineering, Nanjing University of Science and Technology, Nanjing 210094, P.R. China
A microwave-assisted method for the synthesis of polynitrostilbenes involving the condensation of 2,4,6-trinitro-m-xylene and
2,4,6-trinitrotoluene with aryl aldehydes in the presence of piperidine and silica-gel is reported. Compared with conventional
methods, a shorter reaction time is required and this method has a lower environmental impact. A mechanism for the reaction
is also proposed and supported by UV-Vis absorption spectroscopy.
Keywords: polynitrostilbenes, microwave irradiation, silica-gel supported, solvent-free reaction
Polynitrostilbenes, such as 2,2′,4,4′,6,6′-hexanitrostilbene
(HNS)1–3 are well known explosives with excellent thermal
stability and detonation properties. Nitrostilbene-based
compounds are also widely used as organic nonlinear optical
materials4–9 for high-performance electro-optical devices.
The Mizoroki–Heck reaction, Negishi–Stille coupling and
Wittig-type reactions have proved to be quite versatile in the
preparation of different substituted stilbenes. However, they
need transition-metal catalysis and complicated sequences
to form halogen- and phosphorus-containing substrates.10–15
More recently, transition metal catalysts especially palladium
have been widely studied in stilbene syntheses. Other methods
include the McMurry coupling and alkene cross-metathesis as
well as one-pot multicatalytic processes.16–19 These sometimes
lacked stereoselectivity and the cost was increased by using
noble metals. We have reported20 that 2,4,6-trinitro-m-xylene
(TNMX) will condense with two equivalents of aromatic
aldehydes in boiling benzene with a piperidine catalyst. The
whole process was time-consuming but proceeded with high
stereoselectivity.
Recently, microwave-assisted organic synthesis (MAOS)
has developed into a popular branch of synthetic organic
chemistry,21–25 as it helps in minimising the energy
consumption required for heating as well as the time required
for the reaction. However, a combination of microwave and
solvent-free conditions are rare in polynitrostilbene chemistry.
We now report a useful and solvent-free method for the
synthesis of an array polynitrostilbenes based on TNMX and
2,4,6-trinitrotoluene (TNT) with piperidine catalysis utilising
microwave irradiation. To make the system safer, silica-gel was
used as an effective solid support. In order to shed more light
on this reaction, the mechanism of the reaction was also studied
by UV-Vis absorption.
were identified with this oven and a laboratory oven was used.
Silica-gel was used as a security guard with economical and
recyclable properties. Furthermore, by increasing the reaction
temperature to 130 °C, the product 3 was obtained with 75%
yield (Table 1, entry 5). When the reaction was carried out
at 140 °C, no significant change in the yield was observed
(Table 1, entry 6). Increasing the irradiation time to 20 min,
enhanced the yield to 85% (Table 1, entries 6 and 7). On further
increasing the irradiation time, the yield decreased (Table 1,
entry 8). It was observed in this study that the temperature did
not have much influence on the reaction (Table 1, entries 4, 5
and 6). High temperature (more than 150 °C) might cause the
catalyst to evaporate and carbonise since some black substance
appeared. On the other hand, the reaction time proved to
have a great influence on the yield (Table 1, entries 4, 7 and
8). Screening these reaction parameters revealed that a time
of 20 min was most appropriate and the temperature was
controlled at 120 °C.
Finally, we examined the amount of piperidine loaded on the
silica-gel. We carried out the reaction with different amounts of
piperidine. (Table 2) The optimum amount amount of piperidine
loaded on the silica-gel was 2.0 mmol for the synthesis of 3
(Table 1, entry 7). Moreover, to elucidate the importance of
microwave irradiation, we also carried out the reaction under
conventional heating (oil bath) and even after a long reaction
time (100 min) only 45% yield of desired product was achieved
(Table 1, entry 12).
Once we had established the best conditions, we then
examined the scope of the reaction (Table 3). At first, a
variety of aromatic aldehydes were reacted with TNMX in
order to synthesise different polynitrostilbenes. Furthermore,
to reveal the advantages of a microwave-assisted synthesis
of polynitrostilbenes, the traditional thermal assisted results
were also examined. The electronic effects of substituents in
aromatic aldehydes were evaluated and a remarkable effect on
the reaction was discovered. For instance, when there was a
chlorine substituent in the aldehyde, a significant increase in
the reaction time ranging from 26 h to 45 h was observed and
the yield of the products decreased compared to benzaldehyde
in the traditional method. However, by using a microwave-
assisted method the reaction time was controlled at only 20 min
and the yield of the desired products was nearly the same as the
traditional method (Table 2, entries 1–5).
Results and discussion
Initially, we performed the reaction using TNMX, benzaldehyde
and silica-gel in the absence of piperidine with an irradiation
power of 300 W at 120 °C for 15 min. Even though in some
reports, the silica gel supporter was an effective catalyst for
Knoevenagel reactions under microwave irradiation,26–28 no
catalytic effect was found with silica-gel which lacked the basic
strength for this reaction. (Table 1, entries 1 and 2) The two
starting materials were then mixed without silica-gel but in
the presence of piperidine. The reaction was originally carried
out in a domestic microwave oven for 15 min, affording the
desired product 3 in 74% yield (Table 1, entry 3). However,
in some cases, decomposition occurred and potential hazards
If
a
strong electron-withdrawing nitro group was
employed, the corresponding products were obtained in
lower yields. About 5% of the product was achieved after
24 h with ortho-nitrobenzaldehyde using the traditional
method. Notably, the yield increased to 50% by applying
the microwave methodology in 20 min (Table 2, entry 6).
It might be explained by “nonthermal” microwave effects.
* Correspondent. E-mail: xhpeng@mail.njust.edu.cn
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JOURNAL OF CHEMICAL RESEARCH 2014 241
Table 1 Optimisation of silica-gel supported microwave-assisted condensationa
NO2
CHO
NO2
H3C
O2N
CH3
NO2
Silica-gel
Piperidine ,
Microwave 300 W
O2N
NO2
3
1
2
Entry
Piperidine loading/mmol
Time/min
Temperature/°C
Yield/%b
1
2c
3c
4
5
6
7
8
9
10
0.0
0.0
2.0
2.0
2.0
2.0
2.0
2.0
1.5
2.5
3.0
2.0
15
15
15
15
15
120
120
120
120
130
140
120
120
120
120
120
120
0
0
74
73
75
76
85
83
77
85
84
45
15
15
25
20
20
20
100
11
12d
aReactions were carried out with 2.0 mmol of TNMX and 4.2 mmol of benzaldehyde, 3.5 g of
silica gel. Irradiations were carried out in a microwave oven operating at 300 W.
bIsolated yield after recrystallisation of via silica gel column.
cWithout SiO2.
dConventional heating, oil bath.
Table 2 Diversification of polynitrostilbenes via substituted aldehydesa
NO2
NO2
NO2
Ar
Ar
Ar
A)Thermal,piperidine,
O
H3C
O2N
CH3
H3C
O2N
benzene, reflux
+
+
H
Ar
NO2
NO2
B) Microwave, piperidine,
O2N
NO2
silica-gel
mono-condensation
di-condensation
Entry
Ar
Method
Time
Yield of di-/%b
Yield of mono-/%b
Ac
Bd
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
A
B
26 h
20 min
28 h
20 min
26 h
20 min
26 h
20 min
45 h
20 min
24 h
20 min
25 h
20 min
19 h
20 min
12 h
20 min
12 h
20 min
40 h
85
83
81
80
82
80
79
77
70
70
5
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
14
4
20
5
1
2
C6H5-
2-ClC6H4-
3-ClC6H4-
4-ClC6H4-
3
4
5
2,4-Cl2C6H3-
2-NO2C6H4-
3-NO2C6H4-
4-NO2C6H4-
4-CH3C6H4-
4-OCH3C6H4-
3-OHC6H4-
6
50
30
55
0
7
8
0
88
86
89
87
55
64
75
85
9
10
11
12
20 min
24 h
20 min
4-N(CH3)2C6H4-
aReactions were carried out with 2.0 mmol of TNMX and 4.2 mmol of aromatic aldehyde, 2.0 mmol of piperidine.
bIsolated yield after recrystallisation of via silica column.
cBenzene as a solvent, the reflux rate was controlled at about 100 drops/min.
dIrradiations were carried out in a microwave oven operating at 300 W, temperature 120 °C, 3.5 g of silica gel.
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242 JOURNAL OF CHEMICAL RESEARCH 2014
Table 3 Condensation of TNT and aromatic benzaldehydea
CH3
NO2
NO2
N
O2
O2N
O
Ar
+
Piperidine , Silica-gel
Microwave 300W
O2N
H
Ar
NO2
Entry
Ar
Yield/%b
Entry
Ar
Yield/%b
1
2
3
4
5
C6H5-
88
82
83
82
80
6
7
8
9
10
2-NO2C6H4-
3-NO2C6H4-
4-NO2C6H4-
4-CH3C6H4-
78
82
76
82
80
2-ClC6H4-
3-ClC6H4-
4-ClC6H4-
2,4,-Cl2C6H3-
4-N(CH3)2C6H4-
aReactions were carried out with 2.0 mmol of TNT and 2.1 mmol of aromatic aldehyde, piperidine, 2.0 mmol. Irradiations
were carried out in a microwave oven operating at 300 W, temperature 120 °C, time 20 min, silica gel, 3.5 g.
bIsolated yield after recrystallisation.
Using meta-nitrobenzaldehyde as the aldehyde, the yield of
was used for detecting the changes. When we mixed TNMX
with piperidine in an acetonitrile solution, a new absorption
peak appeared around 330 nm. However, no changes happened
in absorption when mixing of benzaldehyde and piperidine
(ESI) It is proposed that the formation of a methylene anion
occurs first with the piperidine catalyst. A plausible pathway
for the synthesis of polynitrostilbenes is illustrated in Scheme 1.
We assumed that initially one of the two methyl groups in
TNMX a was deprotonated by the organocatalyst piperidine
affording the intermediate carbanion b, which then reacted
with the aromatic aldehyde in an aldol reaction and formed
the product c. Subsequently, c was deprotonated to give d in
another piperidine catalysed step and furnished the elimination
product e. The final di-condensation product f was formed by
a similar sequence.
the product was 30% by the traditional method while a 55%
yield was obtained by the microwave irradiation (Table 2, entry
7). Interestingly, para-nitrobenzaldehyde did not undergo in
this reaction at all using the either traditional method or the
microwave (Table 2, entry 8).
Using an electron-donating methyl and methoxyl group in
the para-position in the aldehydes, the corresponding products
were obtained in yields of 88% and 89% by the conventional
method while nearly the same yield was obtained by microwave
methodology (Table 2, entries 9 and 10). Furthermore, it was
observed in this study that mono-condensation products
could be isolated for meta-hydroxybenzaldehyde and para-
dimethylamino-benzaldehyde by the traditional method
(Table 2, entries 11 and 12). However, applying the microwave
methodology, we found that the yield of mono-condensation
products decreased while the di-condensation products
increased.
Conclusion
In summary, we have described a new approach to the synthesis
of polynitrostilbenes. The process takes place under silica-
gel supported solvent-free conditions utilising microwave
irradiation with a piperidine catalyst. Applying this new
methodology, we obtained the desired compounds in good
yields within a short time. Moreover, two mono-condensation
products were separated successfully with TNMX. The
mechanism of this reaction was also studied by UV-Vis
absorption spectra. The extension of this approach to other
polynitrostilbenes and more detailed work on the mechanisms
are in progress in our laboratory.
To establish the generality and scope of the method, the
procedure was successfully applied to TNT and afforded the
desired condensation products in excellent yields, as the methyl
group in TNT was more activated than TNMX (Table 3).
Aromatic aldehydes substituted with a nitro-group also gave
the corresponding products in an acceptable yield (Table 3,
entries 6–8).
Interestingly, when piperidine was added to TNMX solution,
the colour of the solution changed, which gave a better
understanding of this type of reaction. In order to investigate
the mechanism of the condensation, UV-Vis absorption spectra
H
NO2
NO2
NO2
Ar
CH
C
H
H3C
O2N
H3C
O2N
CH3
H3C
O2N
CH2
OH
Piperidine
ArCHO
Piperidine
NO2
N
O2
N
O2
a
c
b
NO2
Ar
H
Ar
NO2
Ar
H
H
N
O2
r
A
H
CH C
NO2
C
C
H3C
O2N
CH
NO2
C
C
H
H3C
O2N
Piperidine, ArCHO
H
OH
O2N
NO2
f
e
d
Scheme 1 Possible mechanism of this type condensation catalysed by piperidine.
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JOURNAL OF CHEMICAL RESEARCH 2014 243
1402, 1347, 979. 1H NMR (500 MHz, CDCl3),ꢀδꢀ8.78ꢀ(s,ꢀ1H),ꢀ7.46ꢀ(s,ꢀ2H),ꢀ
7.37–7.33 (m, 6H), 7.21 (d, J=16.60 Hz, 2H), 6.81 (d, J=16.60 Hz, 2H).
trans,trans-1,3-Di[4′-chlorostyryl]-2,4,6-trinitrobenzene (Table 2,
entry 4): Yellow solid, recrystallisation from ethanol/acetone, m.p.
158–160ꢀ°C,ꢀ IRꢀ (ν,ꢀ cm–1): 3094, 1634, 1588, 1543, 1490, 1333, 972;
1H NMR (500 MHz, CDCl3),ꢀδꢀ8.76ꢀ(s,ꢀ1H),ꢀ7.43–7.37ꢀ(m,ꢀ8H),ꢀ7.17ꢀ(d,ꢀ
J=16.60 Hz, 2H), 6.84 (d, J=16.60 Hz, 2H); 13C NMR (126 MHz,
CDCl3),ꢀδꢀ145.70,ꢀ136.68,ꢀ135.02,ꢀ132.31,ꢀ129.89,ꢀ128.26,ꢀ127.68,ꢀ127.35,ꢀ
120.78, 115.34. HRMS calcd for C22H13Cl2N3O6 (M+H)+: 485.9780,
found 485.9749.
Experimental
CAUTION: Although no problems were encountered during the
synthesis, all polynitrocompounds are explosive and great care must
be taken in all the processes. Safety equipment such as Kevlar gloves,
bar shields, and ear plugs are highly recommended especially when
collecting the energetic materials. It is also advised to work on all small
quantities (<1.0 g). Large-scale reactions require other safety means.
All microwave reactions were carried out in specialised vessels in
the microcomputer microwave chemical reactor WBFY-201. The
temperature was monitored throughout the reaction by an infrared
detector. All chemical reagents and solvents (analytical grade) were
used as supplied unless otherwise stated. All experiments were
monitored by TLC, TLC plates were visualised by exposure to UV
light (254 nm). 1H and 13C spectra were recorded on a Bruker Avance III
500 MHz, using CDCl3 or DMSO-d6 as a solvent. Coupling constants
are reported in Hz. IR spectra were recorded using Bruker Tensor 27
with the sample dispersed in a KBr pellet. Multiplicities: s, singlet; d,
doublet; t, triplet; q, quartet; m, multiplet. Mass spectra were obtained
using an electrospray (ESI-TOF) mass spectrometer 6500 Series and
a Bruker Daltonics flexAnalysis instrument. The UV-Vis absorption
was carried out on Shimadzu UV-1800 Series, wavelength range (nm)
from 220.0 to 600.0, slit width is 1.0 nm and light source wavelength is
340.0 nm.
trans,trans-1,3-Di[2′,4′-dichlorostyryl]-2,4,6-trinitrobenzene
(Table 2, entry 5): Yellow solid, recrystallisation from ethanol/acetone,
1
m.p.ꢀ166–167ꢀ°C,ꢀIRꢀ(ν,ꢀcm–1): 3095, 1633, 1545, 1383, 1339, 976; H
NMR (500 MHz, CDCl3),ꢀδꢀ8.81ꢀ(s,ꢀ1H),ꢀ7.56ꢀ(d,ꢀJ=2.00 Hz, 2H), 7.50
(d, J=8.40 Hz, 2H), 7.32–7.30 (dd, J1 =2.00 Hz, J2 =8.40 Hz, 2H), 7.19
(d, J=16.55 Hz, 2H), 6.77 (d, J=16.55 Hz, 2H); 13C NMR (126 MHz,
CDCl3),ꢀ δꢀ 150.74,ꢀ 145.80,ꢀ 135.30,ꢀ 133.69,ꢀ 133.10,ꢀ 132.40,ꢀ 129.98,ꢀ
129.66, 128.11, 125.46, 120.94, 116.71. HRMS calcd for C22H11Cl4N3O6
(M+H)+: 555.9297, found 555.9294.
trans,trans-1,3-Di[2′-nitrostyryl]-2,4,6-trinitrobenzene (Table 2,
entry 6): Green yellow solid, recrystallisation from acetone, m.p. 212–
213ꢀ°C,ꢀIRꢀ(ν,ꢀcm–1): 3097, 1629, 1603, 1550, 1524, 1341, 975; 1H NMR
(500 MHz, DMSO-d6),ꢀδꢀ9.07ꢀ(s,ꢀ1H)ꢀ8.09ꢀ(d,ꢀJ=8.15 Hz, 2H), 7.86 (d,
J=3.95 Hz, 2H), 7.69–7.66 (m, 4H), 7.50 (d, J=16.45 Hz, 2H), 7.21 (d,
J=16.45 Hz, 2H); 13C NMR (126 MHz, DMSO-d6),ꢀδꢀ149.77,ꢀ147.23,ꢀ
146.48, 133.59, 131.04, 129.89, 129.54, 128.33, 127.86, 124.23, 122.43,
121.96. HRMS calcd for C22H13N5O10 (M+H)+: 508.0210, found (M+H)
508.0206, (M+Na) 530.0121, (M+K) 545.9988.
Traditional thermal synthesis
In a typical experiment, the polynitroaromatic (2.0 mmol), benzene
(40 mL), aromatic aldehyde (4.2 mmol), piperidine (2.0 mmol) were
placed in a 100 mL flask equipped with a Dean-Stark trap. The mixture
was heated to reflux for 15 h or even more. The whole process was
monitored by thin-layer chromatography (TLC). After evaporation of
the benzene (25–30 mL), ethanol was added dropwise to the residue
until a precipitate appeared. Then, the mixture was cooled to room
temperature and placed in a refrigerator overnight. The precipitated
product was collected, washed and dried. The solid was crystallised
from an appropriate solvents. In some cases, when ethanol was added,
no precipitate appeared and the product was isolated via silica gel
column chromatography.
trans,trans-1,3-Di[3′-nitrostyryl]-2,4,6-trinitrobenzene (Table 2,
entry 7): Pale yellow solid, recrystallisation from glacial acetic acid,
m.p.ꢀ 238–240ꢀ°C,ꢀ IRꢀ (ν,ꢀ cm–1): 3084, 1636, 1585, 1529, 1391, 1348,
973; 1H NMR (500 MHz, CDCl3),ꢀδꢀ8.89ꢀ(s,ꢀ1H),ꢀ8.34ꢀ(s,ꢀ2H),ꢀ8.27ꢀ(d,ꢀ
J=8.15 Hz, 2H), 7.82 (d, J=7.50 Hz, 2H),7.64–7.61 (dd, J =8.15 Hz,
1
J2 =7.50 Hz, 2H), 7.34 (d, J=16.45 Hz, 2H), 6.93 (d, J=16.45 Hz,
2H); 13C NMR (126 MHz, CDCl3),ꢀ δꢀ 147.76,ꢀ 145.97,ꢀ 135.34,ꢀ 135.14,ꢀ
131.98, 129.56, 129.13, 127.94, 123.43, 121.13, 121.05, 118.09. HRMS
calcd for C22H13N5O10 (M+H)+: 508.2436, found 508.2439(M+H),
568.2878(M+Na+K).
Microwave irradiation
trans,trans-1,3-Di[4′-methylstyryl]-2,4,6-trinitrobenzene (Table 2,
entry 9): Light yellow solid, recrystallisation from ethanol/acetone;
m.p. 158–159 °C, (lit.29ꢀ158.4ꢀ°C),ꢀIRꢀ(ν,ꢀcm–1): 3096, 1632, 1544, 1543,
1451, 1335, 974. H NMR (500 MHz, CDCl3),ꢀδꢀ8.69ꢀ(s,ꢀ1H),ꢀ7.39(d,ꢀ
J=8.00 Hz 4H), 7.22(d, J=8.00 Hz, 4H), 7.13(d, J=16.55 Hz, 2H), 6.86
(d, J=16.55 Hz, 2H), 2.39(s, 6H).
In a typical experiment, the polynitroaromatic (2.0 mmol) together
with aromatic aldehyde (4.2 mmol) and piperidine (2.0 mmol) were
dissolved in methylene dichloride (15 mL). Then 3.5 g silica gel (48–
75 um) was added and thoroughly mixed. The solution was evaporated
slowly to dryness under normal atmospheric pressure. The solid was
transferred into a specialised vessel and the glass vessel (Pyrex) was
irradiated in a microwave oven during appropriate time at the indicated
power (see Table 2). After cooling, the reaction product was isolated
by extraction of the silica gel with methylene dichloride (2×20 mL) or
acetone (2×20 mL).The organic layer was evaporated to dryness under
reduced pressure to obtain crude product. The product was purified by
recrystallisation or via silica gel column chromatography.
1
trans,trans-1,3-Di[4′-methoxystyryl]-2,4,6-trinitrobenzene (Table 2,
entry 10): Orange yellow solid, recrystallisation from ethanol/
acetone;ꢀm.p.ꢀ160–162ꢀ°C,ꢀIRꢀ(ν,ꢀcm–1): 3094, 1631, 1606, 1585, 1511,
1
1385, 1329, 973; H NMR (500 MHz, CDCl3),ꢀδꢀ8.65ꢀ(s,ꢀ1H),ꢀ7.42ꢀ(d,ꢀ
J=8.40 Hz, 4H), 7.01 (d, J=16.50 Hz, 2H), 6.91 (d, J=8.40 Hz, 4H),
6.82 (d, J=16.50 Hz, 2H), 3.84 (s, 6H); 13C NMR (126 MHz, CDCl3),
δꢀ160.15,ꢀ150.39,ꢀ145.23,ꢀ137.80,ꢀ130.26,ꢀ128.12,ꢀ126.75,ꢀ120.71,ꢀ113.39,ꢀ
112.19, 54.47. HRMS calcd for C24H19N3O8 (M+H)+: 478.2920, found
478.2924.
trans,trans-1,3-Distyryl-2,4,6-trinitrobenzene (Table 2, entry 1):
Yellow solid, recrystallisation from acetone, m.p. 149–150 °C, (lit.20
149.5–151.1ꢀ°C),ꢀIRꢀ(ν,ꢀcm–1): 3095, 1634, 1588, 1541, 1451, 1395, 1344,
trans,trans-1,3-Di[3′-hydroxystyryl]-2,4,6-trinitrobenzene (Table 2,
entry 11): Yellow solid, the product was achieved via silica gel column
withꢀhexane/ethylꢀacetateꢀ(5ꢀ:ꢀ1);ꢀm.p.ꢀ194–196ꢀ°C,ꢀIRꢀ(ν,ꢀcm–1): 3400,
1
968. H NMR (500 MHz, CDCl3),ꢀδꢀ8.72ꢀ(s,ꢀ1H),ꢀ7.50–7.37ꢀ(m,ꢀ10H),ꢀ
7.20 (d, J=16.60 Hz, 2H), 6.90 (d, J=16.6 Hz, 2H).
1
trans,trans-1,3-Di[2′-chlorostyryl]-2,4,6-trinitrobenzene (Table 2,
entry 2): Yellow solid, recrystallisation from ethanol/acetone, m.p.
167–168ꢀ°C,ꢀIRꢀ(ν,ꢀcm–1): 3099, 1631, 1582, 1552, 1534, 1511, 1468, 1386,
3095, 1635, 1609, 1586, 1514, 1395, 1323, 972; H NMR (500 MHz,
DMSO-d6),ꢀ δꢀ 9.60ꢀ (s,ꢀ 2ꢀH),ꢀ 9.00(s,ꢀ 1H),ꢀ 7.29ꢀ (d, J=16.60 Hz, 2 H),
7.23(t, J=7.85 Hz, 2 H), 6.98 (d, J=7.70 Hz, 2 H), 6.94 (s, 2 H), 6.81–
6.78, (dd, J 1 =8.10 Hz, J2 =1.75 Hz, 2H), 6.78 (d, J=16.60 Hz, 2 H); 13
C
1
1334, 966. H NMR (500 MHz, CDCl3),ꢀδꢀ8.82ꢀ(s,ꢀ1H),ꢀ7.66–7.64ꢀ(m,ꢀ
2H), 7.42–7.40 (m, 2H), 7.33–7.32 (m, 4H), 7.29 (d, J=16.60 Hz, 2H),
7.20 (d, J=16.60 Hz, 2H); 13C NMR (126 MHz, CDCl3), 151.01, 145.83,
134.10, 133.32, 132.25, 130.22, 129.83, 129.03, 126.40, 126.27, 120.80,
117.58. HRMS calcd for C22H13Cl2N3O6 (M+H)+: 485.9780, found
485.9776.
trans,trans-1,3-Di[3′-chlorostyryl]-2,4,6-trinitrobenzene (Table 2,
entry 3): Yellow solid, recrystallisation from ethanol/acetone, m.p. 142–
143 °C, (lit.20ꢀ142.5–143.1ꢀ°C),ꢀIRꢀ(ν,ꢀcm–1): 3098, 1631, 1602, 1547, 1473,
NMR (126 MHz, DMSO-d6),ꢀδꢀ157.26,ꢀ149.90,ꢀ145.98,ꢀ136.58,ꢀ135.74,ꢀ
129.96, 129.49, 122.13, 117.87, 116.63, 116.31, 112.99. HRMS calcd for
C22H15N3O8 (M+H)+: 450.0968, found 450.0975, 511.0722(M+Na+K).
3-Methyl-trans-3′-hydroxy-2,4,6-trinitrostilbene (Table 2, entry
11): Yellow solid, the product was achieved via silica gel column with
hexane/ethylꢀacetateꢀ(5ꢀ:ꢀ1);ꢀm.p.ꢀ160–162ꢀ°C,ꢀIRꢀ(ν,ꢀcm–1): 3408, 3092,
1633, 1605, 1576, 1524, 1394, 1313, 975; 1H NMR (500 MHz, CDCl3),
δꢀ 8.71ꢀ (s,ꢀ 1ꢀ H),ꢀ 7.29ꢀ (t,ꢀ J=9.3 Hz, 1H), 7.16 (d, J=16.60 Hz, 1 H),
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244 JOURNAL OF CHEMICAL RESEARCH 2014
7.05(d, J=7.65 Hz, 1 H), 6.95 (t, J=2.05 Hz, 1H), 6.87(dd, J1 =8.05 Hz,
J2 =1.90 Hz, 1H), 6.80 (d, J=16.60 Hz, 1H), 2.60(s, 3H). 13C NMR
(126 MHz, DMSO-d6),ꢀδꢀ157.25,ꢀ151.25,ꢀ147.39,ꢀ145.42,ꢀ136.23,ꢀ135.76,ꢀ
129.94, 129.65, 129.44, 122.03, 117.82, 116.89, 116.25, 112.95, 14.14.
HRMS calcd for C15H11N3O7 (M+H)+: 346.0597, found 346.0592.
trans,trans-1,3-Di[4′-dimethylaminostyryl]-2,4,6-trinitrobenzene
(Table 2, entry 12): Black solid, recrystallisation from ethanol/acetone;
m.p.ꢀ199–200ꢀ°C,ꢀIRꢀ(ν,ꢀcm–1): 3089, 2894, 1606, 1606, 1575, 1525, 1439,
1365, 1327, 1185, 969; 1H NMR (500 MHz, CDCl3),ꢀδꢀ8.56ꢀ(s,ꢀ1H),ꢀ7.38ꢀ
(d, J=8.80 Hz, 4 H), 6.94(d, J=16.40 Hz, 2H), 6.84 (d, J=16.40 Hz,
2H), 6.72 (d, J=6.50 Hz,4 H), 3.03 (s, 12H); 13C NMR (126 MHz,
CDCl3),ꢀ δꢀ 150.44,ꢀ 150.00,ꢀ 144.41,ꢀ 138.71,ꢀ 130.42,ꢀ 128.16,ꢀ 122.43,ꢀ
120.81, 111.11, 109.27, 39.32. HRMS calcd for C26H25N5O6 (M+H)+:
504.1805, found 504.1811.
trans-4′-nitro-2,4,6-trinitrostilbene (Table 3, entry 8): Yellow
solid, recrystallisation from ethanol/acetone; m.p. 195–196 °C, (lit.33
196ꢀ°C),ꢀIRꢀ(ν,ꢀcm–1): 3099, 1698, 1539, 1509, 1401, 1344, 967. 1H NMR
(500 MHz, CDCl3), 8.97 (s, 2H), 8.29(d, J=8.70 Hz, 2H), 7.66(d,
J=8.70 Hz, 2H), 7.53 (d, J=16.65 Hz, 1H), 6.78(d, J=16.65 Hz, 1H).
trans-4′-Methyl-2,4,6-trinitrostilbene (Table 3, entry 9): Light yellow
solid, recrystallisation from ethanol/acetone; m.p. 162–163 °C, (lit.34
162.3ꢀ°C),ꢀIRꢀ(ν,ꢀcm–1): 3083, 1628, 1597, 1536, 1407, 1342, 974.
trans-4′-Dimethylamino-2,4,6-trinitrostilbene (Table 3, entry
10):Yellow solid, recrystallisation from ethanol/acetone; m.p. 232–
233 °C, (lit.34ꢀ232–233ꢀ°C),ꢀIRꢀ(ν,ꢀcm–1): 3092, 3078, 1631, 1580, 1526,
1443, 1362, 1332, 1235, 1170, 962.
This project was funded by the Priority Academic Program
Development of Jiangsu Higher Education Institutions (PAPD).
3-Methyl-trans-4′-dimethylamino-2,4,6-trinitrostilbene (Table 2,
entry 12): Dark green solid, the product was achieved via silica gel
columnꢀwithꢀhexane/ethylꢀacetateꢀ(6ꢀ:ꢀ1);ꢀm.p.ꢀ204–205ꢀ°C,ꢀIRꢀ(ν,ꢀcm–1):
Received 13 January 2014; accepted 14 February 2014
Paper 1402398 doi: 10.3184/174751914X13944453321075
Published online: 2 April 2014
1
3078, 2896, 1580, 1526, 1362, 1332, 1170, 973; H NMR (500 MHz,
CDCl3),ꢀδꢀ8.62ꢀ(s,ꢀ1H),ꢀ7.39ꢀ(d,ꢀJ=8.70 Hz, 2H), 6.94 (d, J=16.45 Hz,
1H), 6.84 (d, J=16.45 Hz, 1H), 6.74 (d, J=6.50 Hz, 2H), 3.04 (s, 6H),
2.57 (s, 3H); 13C NMR (126 MHz, CDCl3),ꢀδꢀ151.63,ꢀ150.54,ꢀ145.64,ꢀ
145.22, 139.16, 130.17, 129.42, 128.78, 128.27, 120.81, 111.15, 108.85,
39.33, 14.04. HRMS calcd for C17H16N4O6 (M+H)+: 373.1070, found
373.1066.
trans-2,4,6-Trinitrostilbene (Table 3, entry 1): Yellow solid,
recrystallisation from ethanol/acetone, m.p. 155–156 °C (lit.11 156 °C),
IRꢀ (ν,ꢀ cm–1): 3104, 3074, 1629, 1600, 1532, 1450, 1402, 1086, 975.
1HNMR (500 MHz, CDCl3),ꢀδꢀ8.86ꢀ(s,ꢀ2H),ꢀ7.49–7.36ꢀ(m,ꢀ5H),ꢀ7.36ꢀ(d,ꢀ
J=16.60 Hz, 1H), 6.79 (d, J=16.60 Hz, 1H).
References
1
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7
trans-2′-Chloro-2,4,6-trinitrostilbene (Table 3, entry 2): Yellow
solid, recrystallisation from ethanol/acetone; m.p. 146–147 °C, (lit.30
145.5–146ꢀ°C),ꢀIRꢀ(ν,ꢀcm–1): 3084, 1630, 1604, 1542, 1469, 1403, 1343,
1
A.M. Moran, G.P. Bartholomew, G.C. Bazan and A.M. Kelley, J. Phys.
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7.43–7.41 (m, 1H), 7.36–7.32 (m, 3H), 7.17 (d, J=16.60 Hz, 1H).
trans-3′-Chloro-2,4,6-trinitrostilbene (Table 3, entry 3): Yellow
solid,ꢀrecrystallisationꢀfromꢀethanol/acetone,ꢀm.p.ꢀ141–142ꢀ°C,ꢀIRꢀ(ν,ꢀ
8
9
S.R. Marder, Chem. Commun., 2006, 131.
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1
cm–1): 3106, 3075, 1636, 1598, 1548, 1473, 1425, 1346, 981; H NMR
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13 B.M. Choudary, S. Madhi, M.L. Kantam, B. Sreedhar and Y. Iwasawa, J.
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(500 MHz, CDCl3),ꢀδꢀ8.91ꢀ(s,ꢀ2H),ꢀ7.48(s,ꢀ1H),ꢀ7.38–7.33ꢀ(m,ꢀ4H),ꢀ6.70ꢀ
(d, J=16.60 Hz, 1H); 13C NMR (126 MHz, CDCl3),ꢀδꢀ149.30,ꢀ145.27,ꢀ
135.98, 135.53, 134.10, 132.42, 129.28, 128.98, 126.29, 124.65, 121.31,
117.13. HRMS calcd for C14H8ClN3O6 (M+H)+: 350.0102, found
350.0105.
trans-4′-Chloro-2,4,6-trinitrostilbene (Table 3, entry 4): Yellow
solid, recrystallisation from ethanol/acetone; m.p. 156–157 °C, (lit.31
154–155ꢀ°C),ꢀIRꢀ(ν,ꢀcm–1): 3103, 3072, 1633, 1597, 1543, 1472, 1421,
1
1342, 978; H NMR (500 MHz, CDCl3),ꢀδꢀ8.89ꢀ(s,ꢀ2H),ꢀ7.43–7.38(dd,ꢀ
J1 =19.05 Hz, J2 =8.60 Hz, 4H), 7.34 (d, J=16.60 Hz, 1H), 6.73 (d,
J=16.60 Hz, 1H).
18 P. Colbon, J.H. Barnard, M. Purdie, K. Mulholland, I. Kozhevnikov and J.
Xiao, Adv. Synth. Catal., 2012, 354, 1395.
trans-2′,4′-Dichloro-2,4,6-trinitrostilbene (Table 3, entry 5): Yellow
solid, recrystallisation from ethanol/acetone, m.p. 165–166 °C,
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1
IRꢀ(ν,ꢀcm–1): 3073, 1635, 1593, 1535, 1469, 1390, 1345, 980; H NMR
(500 MHz, CDCl3),ꢀ δꢀ 8.92ꢀ (s,ꢀ 2H),ꢀ 7.57(d,ꢀ J=2.05 Hz, 1H) 7.50(d,
J=8.35 Hz, 1H), 7.36–7.31 (m, 2H), 6.66 (d, J=16.60 Hz, 1H); 13C
NMR (126 MHz, CDCl3),ꢀ δꢀ 149.28,ꢀ 145.39,ꢀ 134.75,ꢀ 133.71,ꢀ 133.12,ꢀ
132.45, 132.17, 130.01, 128.09, 125.42, 121.36, 117.60. HRMS calcd for
C14H7Cl2N3O6 (M+H)+: 383.9712, found 383.9720.
trans-2′-Nitro-2,4,6-trinitrostilbene (Table 3, entry 6): Yellow
solid, recrystallisation from acetone, m.p. 179–180 °C, (lit.32 181 °C),
25 C.O. Kappe, B. Pieber and D. Dallinger, Angew. Chem. Int. Ed., 2013, 52,
1088.
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IRꢀ(ν,ꢀcm–1): 3112, 3090, 1606, 1541, 1439, 1405, 1347, 969; H NMR
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(500 MHz, CDCl3), 8.99 (s, 2H), 8.15(d, J=8.20 Hz, 1H), 7.75(d,
J=3.70 Hz, 2H), 7.60–7.57 (m, 1H), 7.32 (d, J=16.40 Hz, 1H), 7.26(d,
J=16.40 Hz, 1H).
trans-3′-Nitro-2,4,6-trinitrostilbene (Table 3, entry 7): Yellow solid,
recrystallisation from ethanol/acetone; m.p. 159–160 °C, (lit.32 159 °C),
1
IRꢀ(ν,ꢀcm–1): 3090, 1635, 1600, 1534, 1438, 1410, 1352, 973. H NMR
(500 MHz, CDCl3), 8.96 (s, 2H), 8.34 (s, 1H), 8.25(t, J=8.0 Hz, 1H),
7.82(d, J=8.0 Hz, 1H), 7.62 (t, J=8.0 Hz, 1H), 7.52 (d, J=16.60 Hz,
1H), 6.78(d, J=16.60 Hz, 1H).
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