Synthesis and structures of the CH acid salts obtained in the reactions of malonic acid esters and malononitriles with 2,4,6-trinitrohalobenzenes in the presence of triethylamine

Article abstract of DOI:10.1007/s11172-011-0249-x

Reactions of dimethyl malonate, diphenyl malonate, methyl cyanoacetate, and malono-nitrile with 1-chloro-2,4,6-trinitrobenzene or 1-fluoro-2,4,6- trinitrobenzene in the presence of triethylamine in organic solvents gave stable brightly colored crystalline

Full text of DOI:10.1007/s11172-011-0249-x

Russian Chemical Bulletin, International Edition, Vol. 60, No. 8, pp. 1663—1671, August, 2011
1663
Synthesis and structures of the CH acid salts obtained
in the reactions of malonic acid esters and malononitriles
with 2,4,6ꢀtrinitrohalobenzenes in the presence of triethylamine
Yu. G. Gololobov, S. V. Barabanov, A. S. Peregudov, P. V. Petrovskii,
Z. A. Starikova, V. N. Khrustalev, and I. A. Garbuzova
A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5085. Eꢀmail: Yugol@ineos.ac.ru
Reactions of dimethyl malonate, diphenyl malonate, methyl cyanoacetate, and malonoꢀ
nitrile with 1ꢀchloroꢀ2,4,6ꢀtrinitrobenzene or 1ꢀfluoroꢀ2,4,6ꢀtrinitrobenzene in the presence
of triethylamine in organic solvents gave stable brightly colored crystalline triethylammonium
salts of the corresponding 2,4,6ꢀtrinitrophenylmalonic acid derivatives.
Key words: 2,4,6ꢀtrinitrohalobenzenes, active methylene compounds, triethylammonium
salts, CH acids, malonates.
Most nucleophilic aromatic substitution reactions inꢀ
volving halonitrobenzenes usually follow a twoꢀstep addiꢀ
tion—elimination mechanism.1 The first step leads to
unstable, intensely colored cyclohexadienylide adducts
(σꢀcomplexes 1a,b), which undergo in situ transformaꢀ
tions into new aromatic compounds 2 (Scheme 1).
methods, the conclusions3 about the formation of stable
σFꢀcomplex 1c (Scheme 2).
Scheme 2
Scheme 1
i. Slow. ii. Rapid.
The basic reaction mixture is usually neutralized with
an acid solution, whereupon aromatic compounds are isoꢀ
lated in common ways. The possible formation of reaction
intermediates other than σꢀcomplexes 1a and 1b during
SNAr reactions was first discussed, to the best of our knowꢀ
ledge, by Leffek et al.2 When analyzing the results obtained
in the study3 of a reaction of ethyl malonate with 1ꢀfluoroꢀ
2,4ꢀdinitrobenzene (FDNB) in the presence of triethylꢀ
amine, Leffek et al.2 have disproved, using spectroscopic
i. FDNB.
They have found2 that the reaction of ethyl malonate
with FDNB actually gives, apart from σFꢀcomplex 1c,
unstable triethylammonium salt 4 in equilibrium with
a mixture of CH acid 3 and triethylamine. We replicated
the synthesis2 according to Scheme 2 and ascertained that,
in fact, salt 4 decomposes to CH acid 3 on attempted
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1637—1645, August, 2011.
1066ꢀ5285/11/6008ꢀ1663 © 2011 Springer Science+Business Media, Inc.

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Gololobov et al.
isolation from the solution. In another study,4 a similar
reaction of a substituted CH acid produces a mixture conꢀ
taining, apart from triethylamine hydrochloride, the corꢀ
responding triethylammonium salt with the 2,4,6ꢀtriꢀ
nitrophenyl substituent at the carbanion center. The forꢀ
mation of stable triethylammonium salts of CH acids in
reactions of active methylene compounds with polynitroꢀ
halobenzenes (with FDNB as an example) in the presence
of organic bases was first mentioned in our previous paper.5
Using physicochemical methods (including Xꢀray diffracꢀ
tion) for investigation of the reaction products, we also
demonstrated5 that methyl cyanoacetate arylated with
FDNB is a nonaromatic compound and that all functionꢀ
al groups in the anionic fragment of the salt are highly
conjugated. Earlier,6 we have described brightly colored
triethylammonium salts of 2,4ꢀdinitrophenylcyanoacetꢀ
amides, whose anions are also characterized by a system
of highly conjugated bonds. Apparently, such compounds
can change their properties when exposed to external facꢀ
tors (temperature, electromagnetic radiation, etc.),7 which
may be of interest for the design of practically useful elecꢀ
tronic devices. In addition, one can believe that the
triethylammonium salts of nitroarylated CH acids under
discussion can possess unusual biological properties since
these are organic salts containing nitro groups, which ofꢀ
ten impart a high biological activity to organic comꢀ
pounds.8 In connection with this, we continued to study
the synthesis and properties of new stable triethylammoꢀ
nium salts with a highly conjugated anion.
Scheme 3
i. CTNB, Et3N. ii. FTNB, Et3N.
and the resulting CH acid A is deprotonated by triethylꢀ
amine to the corresponding salt 5—8.
Scheme 4
The instability of triethylammonium salt 4 in THF is
probably due to the relatively low acidity of the correꢀ
sponding CH acid 3. Obviously, triethylammonium salts
of the type 4 will be more stable if (1) stronger starting CH
acids are used (e.g., alkyl cyanoacetates instead of alkyl
malonates)5,6 and (2) the CH acid is arylated with a stronꢀ
ger electron acceptor than the 2,4ꢀdinitrophenyl fragment.
Here we offer a synthetic route to stable triethylammoniꢀ
um salts of CH acids via reactions of malonic and cyanoꢀ
acetic acid esters and malononitrile with 1ꢀfluoroꢀ2,4,6ꢀ
trinitrobenzene (FTNB) in the presence of triethylamine.
Triethylammonium salts 5—8 were obtained in satisꢀ
factory yields from active methylene compounds and
1ꢀchloroꢀ2,4,6ꢀtrinitrobenzene (CTNB) or FTNB in the
presence of triethylamine (Scheme 3). The reaction rate is
sufficiently high, regardless of the solvents used. The
Nꢀarylation of the cyanoꢀcontaining carbanions with
FTNB, which has been noted earlier,9—12 does not occur
in these reactions.
The mechanism of the formation of salts 5—8 accordꢀ
ing to Scheme 3 is unclear. Apparently, the first step inꢀ
volves deprotonation of the active methylene compounds
under the action of triethylamine. The carbanion generatꢀ
ed in this equilibrium process (Scheme 4) reacts with
1ꢀhalotrinitrobenzene to give σꢀcomplex M. The latter
gives up the fluoride ion to the triethylammonium cation
R,R´ = CN, COOMe, COOAr
X = Cl, F
Free CH acid 9 was obtained by arylation of active
methylene compounds as shown in Scheme 5. The same
scheme was used to obtain CH acid 10, which was transꢀ
formed into salt 11 by deprotonation with triethylamine.

2,4,6ꢀTrinitrophenylmalonic acid derivatives
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
1665
Scheme 5
and H, I, and J (for 5) with different locations of the
negative charge.
The IR spectrum of CH acid 9 contains bands at 3096,
1606, and 758 cm–1 (benzene ring) and at 1746 and
1724 cm–1 (standard values for carboxylate groups). At
the same time, the IR spectra of salts 5, 7, and 8 show no
bands characteristic of the aromatic system; the bands of
the C=O groups in salts 5—7 are shifted by 60—150 cm–1
to the lower frequencies, which suggests the involvement
of the carboxylate groups in the chain of conjugation. Apꢀ
parently, some contribution from resonance structure J
provides sufficiently strong hydrogen bonds between the O
atoms of the C=O groups and the proton of the Et3NH+
group (see below). Analogous changes in position and inꢀ
tensity are experienced by the absorption bands due to the
CN groups. In the IR spectrum of salt 7, the band of the
cyano group is much more intense and appears at a subꢀ
stantially lower frequency (2173 cm–1) compared to the
standard values for the CN groups in the starting active
methylene compounds (2215—2230 cm–1). It should be
noted that salt 8 has a strong hydrogen bond between the
proton of the Et3NH+ group and the N atom of the cyano
group (Xꢀray diffraction data, see below), which can be
attributed to some contribution of resonance structure G
(cf. Ref. 6). Solutions of salts 5—8 in acetone are colored
deep cherryꢀred because of their absorption at 500—540 nm.
Comparison of the 1H NMR spectra of CH acids 9 and
10 with those of their salts 5 and 11 showed that the
negative charge acquired by a molecule causes an upfield
shift of the signals for the protons of all functional groups,
i. 1) Et3N; 2) CTNB; 3) HCl. ii. 1) NaH; 2) CTNB; 3) HCl.
The compositions and structures of triethylammoniꢀ
um salts 5—8 and 11 and CH acids 9 and 10 were conꢀ
firmed by elemental analysis, IR spectroscopy, and NMR
spectroscopy; compounds 5—9 were additionally examꢀ
ined by Xꢀray diffraction.
In salts 5—8 and 11, the negative charge of the anion
is delocalized over a system of conjugated double bonds.
The anions of these salts can be represented by resoꢀ
nance structures A, B, C, and D (for 7), E, F, and G (for 8),

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Gololobov et al.
much as in other similar cases.5,6,13 For instance, the proꢀ
tons of the MeO group and the metaꢀprotons of the benꢀ
zene ring in CH acid 9 resonate at δ 3.79 and 9.04, respecꢀ
tively (against δ 3.59 and 8.50 for analogous protons in the
anion of salt 5). Thus, the IR, UVꢀVis, and NMR spectra
of the salts under study suggest that the negative charge in
their anions is delocalized over all the functional groups,
although the contribution from each functional group in
this delocalization can be estimated only qualitatively so far.
Valuable information on the electronic structures of
salts 5, 7, and 8 and free CH acid 9 was obtained by Xꢀray
diffraction (Figs 1—3; Table 1). It can be seen in Table 1
that the geometrical parameters of the central framework
in salts 5, 7, and 8 are equal. The characteristic features
include (a) the shorter Ccarb—CAr bond (C(4)—C(1),
av. 1.434 Å) compared to a single Csp3—CAr bond; (b) the
longer C(4)—C(5) and C(4)—C(9) ring bonds compared
to the aromatic bonds in the benzene ring; (c) the shorter
N(3)—C(7) bond (av. 1.454 Å) and the nearly coplanar
arrangement of the paraꢀnitro group and the benzene ring
(the dihedral angle ϕ2 < 15°); the C—N bonds involving
the orthoꢀnitro groups are on average 1.474 Å, which apꢀ
proximates to the bond lengths in CH acid 9; (d) equalizaꢀ
tion of the bond lengths in the fragment C(5)—C(6)—
C(7)—C(8) as in structure 9, (e) the smaller exocyclic
angle C(5)—C(4)—C(9) (av. 111.8°) compared to this anꢀ
gle in structure 9.
One can infer from Xꢀray diffraction data that, to
a first approximation, resonance structures A and B (for 7),
E and F (for 8), and H and I (for 5) are most favorable.
The Ccarb—CAr bond in the anions is intermediate beꢀ
tween single and double bonds14 and the CAr—pꢀNO2
bond is substantially shorter than the chemically related
CAr—oꢀNO2 bonds. In addition, the paraꢀnitro group
is virtually coplanar with the phenyl ring, while the
orthoꢀnitro groups are noticeably rotated about the CAr—N
bond (see Table 1).
Shortening of the Ccarb—C(CN) and Ccarb—C(COOMe)
bonds and lengthening of the C≡N bonds in the anions,
which are possible in resonance structures C, D, G, and J,
are not very pronounced. Lengthening of the C=O bond
in compounds 5 and 7 (1.235(1) and 1.225(2) Å) is greatly
Table 1. Selected geometrical parameters of the central fragment in compounds 5 and 7—9*
Parameter
5
7
8
9
A
B
Bond
d/Å
C(2)—C(1)
C(3)—C(1)
C(4)—C(1)
C(4)—C(5)
C(5)—C(6)
C(6)—C(7)
C(7)—C(8)
C(8)—C(9)
C(9)—C(4)
C(5)—N(2)
C(7)—N(3)
C(9)—N(4)
N(2)—O
1.444(2)
1.445(2)
1.436(2)
1.436(2)
1.372(2)
1.386(2)
1.380(2)
1.378(2)
1.428(2)
1.478(2)
1.450(2)
1.475(2)
1.224(2),
1.230(2)
1.231(2),
1.232(2)
1.225(2),
1.228(2)
1.430(2)
1.415(2)
1.437(2)
1.420(2)
1.383(2)
1.382(2)
1.387(2)
1.382(2)
1.417(2)
1.473(1)
1.457(1)
1.473(1)
1.227(1),
1.232(1)
1.226(1),
1.235(1)
1.228(1),
1.221(1)
1.409(1)
1.418(1)
1.428(1)
1.426(1)
1.379(1)
1.382(1)
1.382(1)
1.383(1)
1.424(1)
1.473(1)
1.454(1)
1.471(1)
1.226(1),
1.225(1)
1.228(1),
1.228(1)
1.231(1),
1.226(1)
1.527(2)
1.527(2)
1.518(2)
1.399(2)
1.382(2)
1.375(2)
1.376(2)
1.382(2)
1.401(2)
1.472(2)
1.472(2)
1.483(2)
1.230(2),
1.217(2)
1.215(2),
1.224(2)
1.213(2),
1.215(2)
1.530(2)
1.524(2)
1.515(2)
1.397(2)
1.382(2)
1.382(2)
1.377(2)
1.384(2)
1.403(2)
1.479(2)
1.468(2)
1.487(2)
1.231(2),
1.218(2)
1.215(2),
1.229(2)
1.213(2),
1.216(2)
N(3)—O
N(4)—O
Angle
ω/deg
ϕ (N(2)O2)
41.1(1)
15.3(2)
51.1(1)
110.7(1)
125.5(1)
120.7(1)
125.6(1)
38.6(1)
6.1(1)
56.0(1)
1.3(1)
52.4(2)
27.2(2)
12.2(2)
114.1(2)
124.9(2)
122.7(2)
123.7(2)
52.3(2)
19.0(2)
19.1(2)
114.3(2)
125.2(2)
122.9(2)
123.4(2)
1
ϕ (N(3)O2)
2
ϕ (N(4)O2)
67.3(1)
112.6(1)
124.2(1)
121.4(1)
125.1(1)
42.5(1)
112.0(1)
125.1(1)
120.8(1)
124.6(1)
3
C(5)—C(4)—C(9)
C(4)—C(5)—C(6)
C(6)—C(7)—C(8)
C(8)—C(9)—C(4)
*The atomic numbering for the central fragment is shown in Fig. 3.

2,4,6ꢀTrinitrophenylmalonic acid derivatives
O(6)
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
1667
a
C(11)
N(4)
C(9)
O(10)
O(9)
C(16)
C(17)
O(5)
C(8)
O(4)
C(2)
C(1)
C(3)
C(12)
C(4)
C(13)
N(3)
C(7)
H(4N)
N(1)
C(14)
C(5)
N(2)
O(1)
C(6)
O(7)
C(15)
O(3)
O(8)
C(10)
O(2)
O(8)
b
N(1)
C(3)
O(7)
O(2)
N(4)
C(9)
C(10)
C(15)
C(1)
C(2)
C(8)
C(7)
O(1)
C(4)
C(5)
C(16)
O(3)
O(6)
N(5)
C(13)
N(2)
O(4)
N(3)
O(5)
C(6)
C(12)
C(11)
C(14)
c
O(6)
N(2)
O(5)
C(3)
N(5)
C(9)
C(1)
C(8)
C(4)
C(5)
N(1)
C(2)
C(10)
O(4)
C(15)
C(7)
O(1)
N(6)
C(11)
N(4)
O(3)
N(3)
O(2)
C(6)
C(14)
C(12)
C(13)
Fig. 1. Crystal structures of compounds 5 (a), 7 (b), and 8 (c) with atomic thermal displacement ellipsoids (p = 50%). The hydrogen
atoms in structures 7 (b) and 8 (c) are omitted, except for those involved in the hydrogen bonding (indicated with dashed lines).

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Gololobov et al.
O(6)
O(5)
is obvious, although steric repulsions between the cyano
and ester groups of the carbenoid fragment and the orthoꢀ
nitro groups of the trinitrophenyl substituent give rise to a
twistꢀconformation of the anions because of the rotation
about the Ccarb—CAr bond (the angles between the correꢀ
sponding planes are 36.54(2)°, 26.73(3)°, and 20.02(3)° in
compounds 7, 8, and 5, respectively). The above steric
repulsions are also responsible for the deviations of the N
atoms of the orthoꢀnitro groups from the plane of the benꢀ
zene ring (–0.326 and 0.095 Å in 7, –0.193 and 0.178 Å in
8, and –0.259 and 0.139 Å in 5). A similar effect has been
discovered earlier for related amides.6 The bond equalizaꢀ
tion in the fragment C(5)—C(6)—C(7)—C(8) of the benꢀ
zene rings of the anions is probably due to the electronic
and steric effects of the orthoꢀnitro groups, which is more
pronounced in dinitrophenyl amides.6
C(11)
N(4)
O(9)
O(4)
O(3)
C(9)
O(10)
O(7)
C(3)
C(8)
N(3)
C(2)
C(10)
C(4)
C(5)
C(7)
C(6)
C(1)
O(8)
N(2)
O(2)
O(1)
Fig. 2. One of the crystallographically independent molecules in
the crystal structure of compound 9 with atomic thermal disꢀ
placement ellipsoids (p = 50%).
It is known that the size of the endocyclic bond angles
in 1ꢀsubstituted benzene largely depends on the substituꢀ
ent: the endocyclic bond angles at the C atoms in posiꢀ
tions 1, 3, and 5 are reduced by σꢀelectron donors but
increased by σꢀelectron acceptors, as compared to an ideꢀ
alized value of 120°.15,16 The endocyclic bond angles in
the benzene fragments of the anions of compounds 5, 7,
and 8 is consistent well with this concept (see Table 1).
However, it should be noted that the endocyclic bond
angle at the carbenoid C(4) atom in the anions of salts 5,
7, and 8 (110.7(1)°, 112.62(9)°, and 112.01(7)°, respecꢀ
tively is much smaller than an analogous angle in related
amides (114.4(2)° and 114.4(3)° (see Ref. 6) and CH acid
9 (see Table 1). These facts provide further evidence that
the cyano and ester groups are more powerful σꢀelectron
acceptors than the amido group.
The triethylammonium cations and the anions in structuꢀ
res 5, 7, and 8 form ionic pairs through the strong hydrogen
bonds N+—H...O=C and N+—H...N≡C (see Fig. 1). In
the crystals of these compounds, the ionic pairs are stacked.
It is interesting to compare the bond length distribuꢀ
tion in the cyclic fragment of the anion of salt 5 with the
corresponding characteristics of the cyclic fragment in the
stable Meisenheimer σꢀcomplex 12 (Table 3).17
O(6)
N(4)
O(5)
C(2)
C(8)
C(3)
C(4)
O(4)
C(1)
N(3)
C(7)
C(5)
C(6)
C(3)
O(1)
O(3)
N(2)
O(2)
Fig. 3. Central fragment of compounds 5 and 7—9.
due to the intermolecular hydrogen bond N+—H...O=C
(Table 2).
Interestingly, we have found earlier6 that resonance
structures like A and B are preferred in related amides as
well. Note that the conjugation between the carbenoid
and trinitrophenyl fragments in the salts under discussion
When comparing the Xꢀray diffraction and spectroꢀ
scopic (IR and NMR) data for Meisenheimer σꢀcomꢀ
Table 3. Bond lengths d in the stable Meiꢀ
senheimer complex 12 containing the
2,4,6ꢀtrinitrocyclohexadienylide anion17
Table 2. Parameters of the hydrogen bonds in compounds 7—9
Bond
d/Å
Compound
Type of the H bond
H...A*
D...A
C(1)—C(2)
C(2)—C(3)
C(3)—C(4)
C(4)—C(5)
C(5)—C(6)
C(4)—C(7)
1.497
7
8
9
N(5)—H(5N)...O(1)
N(6)—H(6N)...N(1)
N(4)—H(4N)...O(7)
N(4)—H(4N)...O(9)
1.88
1.98
1.97
2.28
2.7896(14)
2.8943(11)
2 . 7 9 7 ( 2 )
2.910(2)
1.355(6)
1.396(6)
1.369(6)
1.378(6)
1.427(6)
* D is the proton donor and A is the proton acceptor.

2,4,6ꢀTrinitrophenylmalonic acid derivatives
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
1669
plexes17 with those for the anionic part of salts 5, 7, and 8,
one can conclude that they have closely related electronic
configurations. Analogous conclusions can be drawn from
comparison of the structures of Meisenheimer complexes
with the structures of the anions of the salts and zwitterꢀ
ions described earlier.5,6,9—12 Note, however, that the ring
C(4) atom in mesomeric ions 5, 7, and 8 has a nearꢀsp2
configuration, while the spiro C atom in Meisenheimer
complex 12 is sp3ꢀhybridized. Because the C(1)—C(4)
bond in the anions of salts 5, 7, and 8 is partially double,
their negative charge is delocalized over a longer chain
(compared to Meisenheimer complexes) including not
only the pꢀNO2 group of the benzene ring but also the
exocyclic ester and cyano groups.
When summing up the results obtained in this study
and previous data,3 one can conclude that attachment of
the 2,4,6ꢀtrinitrophenyl (instead of 2,4ꢀdinitrophenyl)
moiety to the central C atom of active methylene comꢀ
pounds makes the corresponding triethylammonium salts
more stable and allows their synthesis from not only malꢀ
onates but also less reactive CH acids. Development of the
latter approach will be useful for practical applications of
the discussed concept of designing stable monomeric,
dimeric, and polymeric triethylammonium salts with
a highly conjugated anion.
B. Triethylamine (0.55 mL, 4.00 mmol) was added to a soluꢀ
tion of methyl cyanoacetate (0.20 g, 2.00 mmol) and CTNB
(0.50 g, 2.00 mmol) in DMF (5 mL). The solution turned dark
cherry instantaneously; the reaction was exothermic. After 24 h,
triethylamine hydrochloride (180 mg, 65%) was separated. The
residue was crystallized from diethyl ether—acetone (1 : 1). The
yield of the product was 0.50 g (60%), m.p. 130—132 °C. Found (%):
C, 46.75; H, 5.04; N, 16.91. C10H5N4O8•C6H16N. Calculatꢀ
1
ed (%): C, 46.71; H, 5.11; N, 17.03. H NMR (CDCl3), δ: 1.39
3
(t, 9 H, CH3CH2N, JH,H = 7.3 Hz); 3.19 (q, 6 H, MeCH2N,
3JH,H = 7.3 Hz); 3.59 (s, 3 H, Me); 8.50 (s, 2 H, HAr); 9.75
(s, 1 H, NH). IR (Nujol), ν/cm–1: 2173 (CN), 1630 (CO), 1597
(system of the conjugated bonds), 1334 (NO2). UVꢀVis (aceꢀ
tone), λ/nm: 536 (ε 41 400).
Diphenyl 2,4,6ꢀtrinitrophenylmalonate, triethylammonium
salt (6). A solution of triethylamine (0.39 g, 4.0 mmol) in diethyl
ether (5 mL) was added dropwise at 5 °C to a stirred solution of
diphenyl malonate (0.5 g, 2.0 mmol) and CTNB (0.58 g,
2.3 mmol) in diethyl ether (10 mL). After 24 h, the precipitate of
triethylamine hydrochloride that formed was filtered off and the
mother liquor was placed in a refrigerator. After 72 h, product 6
(61%) was isolated as bright dark red crystals, m.p. 125—127 °C.
Found (%): C, 56,89; H, 4.96; N, 9.78. C27H28N4O10. Calculatꢀ
ed (%): C, 57,04; H, 4.93; N, 9.86. IR (KBr pellets), ν/cm–1
:
1712, 1594 (CO), 1335, 1191 (NO2). 1H NMR (CDCl3, 600.220
MHz), δ: 1.18 (t, 9 H, CH3CH2N, 3JH.H = 7.32 Hz); 2.96 (q, 6 H,
MeCH2N, 3JH.H = 7.32 Hz); 6.98 (m, 4 H, oꢀHPh); 7.15 (m, 2 H,
pꢀHPh); 7.28 (m, 4 H mꢀHPh); 8.77 (s, 2 H, C6H2(NO2)3). UVꢀVis
(acetone), λ/nm: 517 (ε 21 150).
According to the spectroscopic (IR, UVꢀVis, and
NMR) and Xꢀray diffraction data, the anionic charge in
the salts of the CH acids under study is delocalized more
strongly than that in salts containing the 2,4ꢀdinitrophenyl
substituent at the carbanionic center.5,6
Bis(4ꢀfluorophenyl) 2,4,6ꢀtrinitrophenylmalonate (10). Sodiꢀ
um hydride (0.32 g, 6.0 mmol) was added in small portions to
a solution of bis(4ꢀfluorophenyl) malonate (1 g, 3.0 mmol) in THF
(5 mL). After 10 min, CTNB (0.85 g, 3.0 mmol) in THF (5 mL)
was added under nitrogen. The solution turned intense red inꢀ
stantaneously, the color intensity increasing with time. After
24 h, the solvent was removed in vacuo and the residue was
washed with benzene and acidified with a solution of CF3COOH
in benzene. The precipitate that formed was filtered off, the
mother liquor was concentrated, and the residue was recrystalꢀ
lized from diethyl ether—acetone. The yield of compound 10
was 80—90%, light yellow fibrous crystals, m.p. 89—91 °C.
Found (%): C, 50.41; H, 2.51; N, 8.05; F, 7.13. C21H11N3O10F2.
Calculated (%): C, 50.10; H, 2.19; N, 8.35; F, 7.13. IR (KBr
pellets), ν/cm–1: 1767, 1741 (CO), 1545, 1356 (NO2). 1H NMR
(CDCl3, 400 MHz), δ: 5.91 (s, 1 H, CH); 7.09 (m, 8 H, FC6H4);
9.13 (s, 2 H, C6H2(NO2)3). 19F NMR (CDCl3, 282.4 MHz), δ:
–115.04 (s, FC6H4).
Experimental
NMR spectra were recorded on a Bruker AMXꢀ400 specꢀ
trometer (400.1 (1H) and 282.4 MHz (19F)). IR spectra were
recorded on a MagnaꢀIRꢀ750 FTIR spectrometer (Nicolet).
UVꢀVis spectra were recorded on a Specord Mꢀ40 spectrometer
in acetone. Reactions were carried out under dry nitrogen.
Methyl 2ꢀcyanoꢀ2ꢀ(2,4,6ꢀtrinitrophenyl)acetate, triethylꢀ
ammonium salt 7. A. Triethylamine (1.2 mL, 8.6 mmol) was
added to a stirred solution of methyl cyanoacetate (0.42 g,
4.3 mmol) and FTNB (0.1 g, 4.3 mmol) in benzene (5 mL). The
solution turned colored immediately, with gradual segregation
of a dark mass. After 2 h, the solution was separated, the segreꢀ
gated dark mass was washed three times with diethyl ether and
mixed with a minimum amount of acetone. The resulting soluꢀ
tion was added to a fivefold amount of light petroleum. The mass
that formed was kept in vacuo and dissolved in ethyl acetate.
The resulting solution was kept at –15 °C for 24 h. The black
crystals that formed were filtered off. The yield of salt 7 was
62.5%, m.p. 130—132 °C. Found (%): C, 46.75; H, 5.04; N, 16.91.
C10H5N4O8•C6H16N. Calculated (%): C, 46.71; H, 5.11;
N, 17.03. 1H NMR (CDCl3), δ: 1.39 (t, 9 H, CH3CH2N,
3JH,H = 7.3 Hz); 3.19 (q, 6 H, MeCH2N, 3JH,H = 7.3 Hz); 3.59
(s, 3 H, Me); 8.50 (s, 2 H, HAr); 9.75 (s, 1 H, NH). IR (Nujol),
ν/cm–1: 2173 (CN), 1630 (CO), 1597 (system of the conjugated
bonds), 1334 (NO2). UVꢀVis (acetone), λ/nm: 536 (ε 41 400).
Bis(4ꢀfluorophenyl) 2,4,6ꢀtrinitrophenylmalonate, triethylꢀ
ammonium salt (11). Triethylamine (0.26 g, 2.5 mmol) was addꢀ
ed to a solution of CH acid 10 (0.65 g, 1.3 mmol) in a mixture of
light petroleum (1 mL), acetone (2 mL), and toluene (2 mL).
The solution turned intense red instantaneously. The reaction
mixture was kept at –15 °C for 24 h. The precipitate that formed
was recrystallized from the above system of solvents. Storage at
–15 °C for 10 days produced dark red crystals. The yield of prodꢀ
uct 11 was 70%, m.p. 110—112 °C. Found (%): C, 53.95; H, 4.56;
N, 8.91; F, 6.65. C27H26N4O10. Calculated (%): C, 53.64;
H, 4.30; N, 9.27; F, 6.29. IR (KBr pellets), ν/cm–1: 1715, 1601
(CO), 1335, 1175 (NO2). 1H NMR (CDCl3, 400 MHz), δ: 1.15
3
(t, 9 H, CH3CH2N, JH,H = 8.0 Hz); 2.92 (q, 6 H, MeCH2N,
3JH,H = 8.0 Hz); 6.92 (m, 8 H, FC6H4); 8.74 (s, 2 H, C6H2(NO2)3).

1670
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
Gololobov et al.
19F NMR (CDCl3, 282.4 MHz), δ: –115.24 (s, FC6H4). UVꢀVis
(acetone), λ/nm: 521 (ε 18 800).
extracted with CH2Cl2 (3×15 mL). The combined extracts were
dried with Na2SO4 and concentrated. The residue was dissolved
in CH2Cl2—MeCN and the resulting solution was gradually acidꢀ
ified with 3% HCl. The organic layer was dried with Na2SO4 and
concentrated in vacuo. The residue was crystallized and recrysꢀ
tallized from acetone. The yield of compound 9 was 0.5 g (29%),
light yellow crystals, m.p. 145—147 °C. Found (%): C, 38.33;
H, 2.53; N, 12.11. C11H9N3O10. Calculated (%): C, 38.48; H, 2.62;
N, 12.24. IR, ν/cm–1: 1746, 1724 (C=O); 1545, 1356 (NO2);
3096, 1606, 758 (arom. ring). 1H NMR (CDCl3), δ: 3.79 (s, 6 H,
MeO); 9.04 (s, 2 H, HAr).
2,4,6ꢀTrinitrophenylmalononitrile, triethylammonium salt (8).
A solution of triethylamine (2.76 g, 20 mmol) in CH2Cl2 (20 mL)
was added dropwise to a stirred iceꢀcooled mixture of malonoꢀ
nitrile (0.66 g, 10 mmol) and CTNB (2.47 g, 10 mmol) in CH2Cl2
(5 mL). The reaction was exothermic. The reaction mixture was
stirred for 2 h, kept at room temperature for 12 h, and poured
into diethyl ether—light petroleum (1 : 1, 50 mL). The mass that
segregated was mixed with acetone. The precipitate of triethylꢀ
amine hydrochloride (1.4 g) was filtered off. The acetone was
removed in vacuo and the residue was washed with toluene, light
petroleum, and diethyl ether. The remaining dark mass was
dissolved in acetone and the solution was poured into ethaꢀ
nol—water (1 : 1). The orange precipitate that formed was dried.
The yield of salt 8 was 2.55 g (67%). Found (%): C, 47.41;
H, 4.69; N, 22.11. C15H18N6O6. Calculated (%): C, 47.62;
Dimethyl 2,4,6ꢀtrinitrophenylmalonate, triethylammonium
salt (5). Triethylamine (1.5 mL, 10 mmol) was added at 5 °C to
a stirred mixture of dimethyl malonate (0.57 g, 5 mmol) and
CTNB (1.23 g, 5 mmol) in diethyl ether (10 mL). The resulting
mixture was left for 12 h. The precipitate (2.4 g) that formed was
washed with acetone—diethyl ether (1 : 1). Triethylamine hydroꢀ
chloride (1.4 g) was filtered off. The solution was kept at –15 °C
for 24 h. The black precipitate that formed was dissolved in
acetone and the resulting solution was kept again at –15 °C for
24 h. The yield of product 5 was 1.0 g (45%), black crystalline
solid, m.p. 133—135 °C. Found (%): C, 46.07; H, 5.44; N, 12.66.
C17H24N4O10. Calculated (%): C, 45.94; H, 5.4; N, 12.61. IR,
ν/cm–1: 1689, 1597 (C=O), 1331 (NO2), 2827 (NH+). 1H NMR
(CDCl3), δ: 1.31 (t, 9 H, CH3CH2N, J = 7.24 Hz); 3.14 (q, 6 H,
MeCH2N, J = 7.24 Hz); 8.58 (s, 2 H, HAr); 10.11 (br.s, 1 H,
NH). 13C NMR (acetoneꢀd6), δ: 8.19 (CH3CH2N); 46.26
(MeCH2N); 48.22 (MeO); 74.8 (C–); 122.54 (CHAr); 138.40
(C—NO2ꢀp). UVꢀVis (acetone), λ/nm: 526 (ε 12 500).
Dimethyl 2,4,6ꢀtrinitrophenylmalonate (9). Triethylamine
(1.5 mL, 10 mmol) was added dropwise to a stirred mixture of
dimethyl malonate (0.66 g, 5.0 mmol) and CTNB (1.23 g,
5 mmol) in acetonitrile (2 mL). A slightly exothermic reaction
produced a black precipitate. After 2 h, the mixture was diluted
with acetone (20 mL) and mixed with water. The product was
Table 4. Crystallographic parameters and the data collection and refinement statistics for compounds 5 and 7—9
Parameter
Value
5
C17H24N4O10
444.40
7
C16H21N5O8
411.38
8
C15H18N6O6
378.35
9
C11H18N3O10
686.42
Molecular formula
Molecular mass
T/K
120
100
100
100
Crystal color and shape
Crystal dimensions (mm)
Crystal system
Space group
a/Å
b/Å
c/Å
α/deg
β/deg
Red plate
0.55×0.35×0.25
Triclinic
P –1
9.0455(7)
10.4472(8)
11.8088(9)
64.374(1)
85.670(2)
88.561(2)
1003.3(1)
2
Dark red prism
0.30×0.15×0.10
Triclinic
P –1
7.9663(5)
11.2277(7)
11.9043(7)
104.975(1)
99.672(1)
107.652(1)
944.41(10)
2
Dark red prism
0.25×0.20×0.20
Triclinic
P –1
7.9031(4)
10.1588(5)
12.3014(6)
68.683(1)
87.100(1)
73.427(1)
880.28(8)
2
Colorless plate
0.50×0.35×0.25
Monoclinic
P21/n
8.9399(7)
14.373(1)
21.997(2)
90.0
100.183(2)
90.0
γ/deg
3
V/Å
2781.9(4)
4
1.639
1408
0.148
Z
dcalc/g cm–3
F(000)
1.471
467
0.122
1.447
432
0.118
1.427
396
0.113
μ/mm–1
2θmax/deg
Number of reflections
measured
independent
56
65
60
54
10387
4825
14173
6841
11211
5072
28002
6054
(Rint
with I > 2σ(I)
)
(0.0216)
3717
(0.0294)
5120
(0.0155)
4462
(0.03625)
4983
Number of parameters refined
282
266
247
433
R1 (I > 2σ(I))
wR2 (all reflections)
GOOF
0.0426
0.0972
1.019
0.0452
0.1125
1.000
0.0341
0.0919
1.000
0.0417
0.1056
1.010

2,4,6ꢀTrinitrophenylmalonic acid derivatives
Russ.Chem.Bull., Int.Ed., Vol. 60, No. 8, August, 2011
1671
H, 4.76; N, 22.22. IR, ν/cm–1: 1330, 1298 (NO2); 2172, 2199 (CN);
3. P. Baudet, Helv. Chim. Acta, 1965, 49, 545.
4. M. Strauss, R. Torres, J. Org. Chem., 1989, 54, 756.
1
2748 (NH+). H NMR (acetoneꢀd6), δ: 1.42 (t, 9 H, CH3CH2,
3
3JH,H = 7.28 Hz); 3.48 (q, 6 H, MeCH2, JH,H = 7.28 Hz); 7.1
5. Yu. G. Gololobov, O. A. Linchenko, P. V. Petrovskii, Z. A.
Starikova, I. A. Garbuzova, Heteroat. Chem., 2007, 18, 108.
6. Yu. G. Gololobov, I. R. Gol´ding, F. Terrier, P. V. Petrovꢀ
skii, K. A. Lyssenko, I. A. Garbuzova, Izv. Akad. Nauk,
Ser. Khim., 2009, 2365 [Russ. Chem. Bull., Int. Ed., 2009,
58, 2445].
(br.s, 1 H, NH); 8.45 (s, 2 HAr).
Xꢀray diffraction studies of compounds 5 and 7—9. The unit
cell parameters and reflection intensities for compounds 7—9
were measured on a Bruker APEX II CCD automatic threeꢀ
circle diffractometer (λMoKα radiation, graphite monochroꢀ
mator, ϕ and ω scan modes). For compound 5, the experiment
was carried out on a Bruker SMART 1000 CCD diffractometer.
Selected crystallographic parameters and the data collection and
refinement statistics are summarized in Tables 1—4. The strucꢀ
tures of all the compounds were solved by the direct methods
and refined anisotropically by the fullꢀmatrix leastꢀsquares method
7. G. Inzelt, Conducting Polymers, Springer, Berlin—Heidelꢀ
berg, 2008.
8. M. D. Mashkovskii, Lekarstvennye sredstva [Drugs], 1985,
1—2, 10th ed., Novaya Volna, Moscow, 2002 (in Russian).
9. Yu. G. Gololobov, O. A. Linchenko, P. V. Petrovskii, I. A.
Garbuzova, V. N. Khrustalev, Izv. Akad. Nauk, Ser. Khim.,
2006, 1261 [Russ. Chem. Bull., Int. Ed., 2005, 55, 1309].
10. Yu. G. Gololobov, O. A. Linchenko, P. V. Petrovskii, Z. A.
Starikova, I. A. Garbuzova, Izv. Akad. Nauk, Ser. Khim.,
2005, 2393 [Russ. Chem. Bull., Int. Ed., 2005, 54, 2471].
11. Yu. G. Gololobov, O. A. Linchenko, P. V. Petrovskii, V. N.
Khrustalev, I. A. Garbuzova, Mendeleev Commun., 2007,
17, 232.
12. Yu. G. Gololobov, V. N. Khrustalev, N. V. Slepchenkov,
A. S. Peregudov, M. Yu. Antipin, Mendeleev Commun., 2010,
20, 39.
13. F. Terrier, E. Magnier, E. Kizilian, C. Wakselman, E. Bunꢀ
cel, J. Am. Chem. Soc., 2005, 127, 5563.
on F2 for nonꢀhydrogen atoms. The hydrogen atoms of the
hkl
amino groups of the cations were objectively located from elecꢀ
tronꢀdensity difference maps and refined with fixed coordinates
and thermal parameters. The other hydrogen atoms were locatꢀ
ed geometrically and refined with fixed coordinates (using
a riding model) and thermal parameters (Uiso(H) = 1.5Uequiv(C)
for the Me groups and Uiso(H) = 1.2Uequiv(C) for the other
groups). All calculations were performed with the SHELXTL
program package.18
The tables of atomic coordinates, bond lengths, bond angles,
and anisotropic thermal parameters for compounds 5 and 7—9
have been deposited with the Cambridge Crystallographic Data
Center (CCDC Nos 768508—768511).
14. International Tables for Crystallography, 2006, Vol. C, Ch.
9.5, pp. 790—811.
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 08ꢀ03ꢀ00196a).
15. A. Domenicano, A. Vaciago, C. A. Coulson, Acta Crystalꢀ
logr., 1975, 31, 221.
16. A. Domenicano, A. Vaciago, Acta Crystallogr., 1979, 35, 1382.
17. O. Ya. Borbulevych, J. Chem. Crystallogr., 2005, 35, 777.
18. G. M. Sheldrick, Acta Crystallogr., 2008, 64, 112.
References
1. F. Terrier, Nucleophilic Aromatic Displacement, WileyꢀVCH,
Weinheim, 1991, 420 pp.
Received July 28, 2010;
2. K. T. Leffek, P. H. Tremaine, Can. J. Chem., 1971, 49, 1979.
in revised form February 1, 2011