The properties and structure of N-chloro-N-methoxy-4-nitrobenzamide

Article abstract of DOI:10.1016/j.mencom.2012.05.019

The XRD study of N-chloro-N-methoxy-4-nitrobenzamide revealed the high pyramidality degree of its amide nitrogen atom in O-N-Cl moiety. N-Chloro-N-methoxy-4-nitrobenzamide reacts with AcONa in MeCN selectively forming N-acetoxy-N-methoxy-4-nitrobenzamide,

Full text of DOI:10.1016/j.mencom.2012.05.019

Mendeleev
Communications
Mendeleev Commun., 2012, 22, 164–166
The properties and structure of N-chloro-N-methoxy-4-nitrobenzamide†
Vasiliy G. Shtamburg,*a,b Alexander V. Tsygankov,c Oleg V. Shishkin,d Roman I. Zubatyuk,d
Boris V. Uspensky,b Victor V. Shtamburg,b Alexander V. Mazepae and Remir G. Kostyanovsky*f
a Ukrainian State Chemico-Technological University, 49038 Dnepropetrovsk, Ukraine.
E-mail: stamburg@gmail.com
b National Technical University ‘Kharkov Polytechnical Institute’, 61002 Kharkov, Ukraine.
E-mail: polytehnik@gmail.com
c State Flight Academy of Ukraine, 25005 Kirovograd, Ukraine. E-mail: geminalsystemsn@gmail.com
d STC ‘Institute for Single Crystals’, National Academy of Sciences of Ukraine, 61001 Kharkov, Ukraine.
E-mail: shishkin@xray.isc.kharkov.com
e A. V. Bogatsky Physico-Chemical Institute, National Academy of Sciences of Ukraine, 65080 Odessa,
Ukraine. E-mail: almazepa@rambler.ru
f
N. N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, 119991 Moscow,
Russian Federation. Fax: +7 499 137 8284; e-mail: kost@center.chph.ras.ru
DOI: 10.1016/j.mencom.2012.05.019
The XRD study of N-chloro-N-methoxy-4-nitrobenzamide revealed the high pyramidality degree of its amide nitrogen atom in O–N–Cl
moiety. N-Chloro-N-methoxy-4-nitrobenzamide reacts withAcONa in MeCN selectively forming N-acetoxy-N-methoxy-4-nitrobenz-
amide, whereas its methanolysis in the presence of AcONa yields N,N'-bis(4-nitrobenzoyl)-N,N'-dimethoxyhydrazine.
As it was shown by S. A. Glover et al.,2–10 N-X-N-alkoxycarbox-
amides [X = OC(O)R, OAlk, Cl] represent a new unusual family
of amides, or anomeric amides. The presence of two strongly
electronegative substituents with lone electron pairs (Lp) should
effect the pyramidality of the amide nitrogen atom which should
be sp3 hybridized.2,10 In the O–N–X group of anomeric amides
the N–X bond should be elongated and destabilized and N–OAlk
bond should be shortened due to nO(Alk) ® s*N–X anomeric effect
action.2–9
The high IR n values of C=O group in most of such amides
was recognized as the argument for their nitrogen pyramidality,2,6
which was later confirmed by XRD studies.9–15 However, XRD
evidence for the case of N-chloro-N-alkoxybenzamides was lacking
because of their lability.
AcONa/
MeCN
MeO
MeO
MeO
ButOCl
NH
O
N
O
Cl
N
OAc
Ar
Ar
Ar
O
1
2
3
– Cl–
MeOH /AcONa
– MeOH+
O
MeO
MeO
Ar
OMe
N
O
N
O
N
Ar = 4-O2NC6H4
Ar
Ar
A
4
Herein, we have fulfilled XRD study of N-chloro-N-methoxy-
4-nitrobenzamide which was synthesized by the chlorination of
N-methoxy-4-nitrobenzamide (Scheme 1).‡ In fact, the investiga-
Scheme 1
N-Acetoxy-N-methoxy-4-nitrobenzamide 3. The solution of amide 2
(0.198 g, 0.856 mmol) in MeCN (15 ml) and AcONa (0.246 g, 3.00 mmol)
was stirred at 18–20°C for 32 h. Then CH2Cl2 (8 ml) was added, the
precipitate was filtered off, washed with CH2Cl2 (6 ml). The combined
filtrate was evaporated in vacuo, the residue was extracted with CH2Cl2
(8 ml), the extract was evaporated in vacuo, yielding 0.205 g (94%) of
amide 3, firstly as viscous oil, which then converted into colourless
crystals, mp 65–67°C (CH2Cl2–C6H14). 1H NMR (500 MHz, CDCl3) d:
2.175 (s, 3H, NOAc), 3.966 (s, 3H, NOMe), 7.937 (d, 2H, C2H, C6H,
3J 9.5 Hz), 8.316 (d, 2H, C3H, C5H, 3J 9.5 Hz). MS (FAB, H+): 255
[M+H]+ (2.5), 213 (5.5), 195 [M–AcO]+ (18), 150 (100). MS (FAB, K+):
293 [M+K]+ (12), 195 [M–AcO]+ (19), 150 (100). Found (%): N, 10.85.
Calc. for C10H10N2O6 (%): N, 11.02.
†
Geminal Systems. Part 62. For the previous communication, see ref. 1.
N-Methoxy-4-nitrobenzamide 1. 4-Nitrobenzoyl chloride (1.573 g,
‡
8.925 mmol) was added to the solution of methoxyamine (0.270 g,
8.925 mmol) and 2,6-dimethylpyridine (0.956 g, 8.925 mmol) in MeCN
(10 ml) at –22°C, the reaction mixture was heated to 20°C within 21 h
and kept at 20°C for 5 days, then it was evaporated in vacuo. The residue
was washed with water (15 ml), dried in vacuo at 1 Torr, yielding 1.491 g
(85%) of amide 1, yellow-white crystals, mp 176–179°C (CHCl3). 1H NMR
(500 MHz, DMSO-d6) d: 3.75 (s, 3H, OMe), 7.99 (d, 2H, C2H, C6H,
3J 10.8 Hz), 8.32 (d, 2H, C3H, C5H, 3J 10.8 Hz), 12.09 (br.s, 1H, NH).
Found (%): N, 14.02. Calc. for C8H8N2O4 (%): N, 14.28.
N-Chloro-N-methoxy-4-nitrobenzamide 2. The solution of ButOCl
(0.455 g, 4.191 mmol) in CH2Cl2 (2 ml) was added to the mixture of
N-methoxy-4-nitrobenzamide 1 (0.154 g, 0.785 mmol) and CH2Cl2 (5 ml)
at –25°C. The reaction mixture was kept at 5°C for 2.5 h, then it was
evaporated in vacuo. The residue was dissolved in CH2Cl2 (2 ml), and
then hexane (8 ml) was added. After keeping at 5°C the precipitate thus
formed was filtered off, dried in vacuo, yielding 0.142 g (78%) of amide 2,
white crystals, mp 93–95°C (decomp.). 1H NMR (500 MHz, CDCl3) d:
3.908 (s, 3H, OMe), 7.933 (d, 2H, C2H, C6H, 3J 9.5 Hz), 8.333 (d, 2H,
C3H, C5H, 3J 9.5 Hz). MS (FAB): 233 [M+H]+ (7.5), 231 [M+H]+ (22.5),
197 (100).
N,N'-Bis(4-nitrobenzoyl)-N,N’-dimethoxyhydrazine 4. The solution
of N-chloro-N-methoxy-4-nitrobenzamide 2 (0.086 g, 0.373 mmol) in
THF (2 ml) was added to the solution of AcONa (0.100 g, 1.220 mmol)
in MeOH (10 ml) at –23°C, the reaction mixture was heated to 20°C
within 24 h, MeOH was evaporated in vacuo, the residue was extracted with
CH2Cl2 (15 ml). The extract was evaporated in vacuo yielding 0.072 g
(99%) of the product 4, white crystals, mp 86–88°C (decomp.). 1H NMR
(500 MHz, CDCl3) d: 4.001 (s, 6H, NOMe), 8.233 (d, 4H, C2H, C6H,
3J 9.0 Hz), 8.311 (d, 4H, C3H, C5H, 3J 9.0 Hz). MS (FAB, H+): 391
[M+H]+ (7), 55 (100). MS (FAB, K+): 429 [M+K]+ (19.5), 192 (100).
Found (%): N, 14.20. Calc. for C16H14N4O8 (%): N, 14.35.
© 2012 Mendeleev Communications. All rights reserved.
– 164 –

Mendeleev Commun., 2012, 22, 164–166
C(8)
O(1)
O(3)
O(6)
C(9)
C(4)
Cl(1)
C(7)
C(2)
C(1)
N(1)
C(3)
C(2)
O(1)
N(1)
C(5)
C(6)
N(2)
C(1)
C(10)
O(2)
C(3)
O(5)
O(4)
O(3)
C(6)
C(5)
C(4)
N(2)
C(7)
O(2)
C(8)
O(4)
Figure 2 Molecular structure of compound 3. Selected bond lengths (Å) and
bond angles (°): O(1)–N(1) 1.3970(18), O(5)–N(1) 1.4214(16), O(2)–C(1)
1.2035(18), N(1)–C(1) 1.4113(19), O(6)–C(9) 1.1863(19), C(1)–C(2) 1.493(2);
O(1)–N(1)–O(5) 107.99(11), O(1)–N(1)–C(1) 112.04(13), C(1)–N(1)–O(5)
110.26(11).
Figure 1 Molecular structure of compound 2. Selected bond lengths (Å) and
bond angles (°): Cl(1)–N(1) 1.7288(14), O(2)–N(1) 1.3967(17), N(1)–C(1)
1.408(2), O(1)–C(1) 1.2046(19), C(1)–C(2) 1.490(2); O(2)–N(1)–C(1)
112.76(12), O(2)–N(1)–Cl(1) 110.84(10), C(1)–N(1)–Cl(1) 113.89(10).
tions done confirmed amide N(1) nitrogen pyramidal configura-
tion (Figure 1). The sum of bond angles centered at this nitrogen
atom (Sß) is 337.5(3)°, the deviation of N(1) atom from the
plane of bonded with N(1) atoms (hN) is equal to 0.418(2) Å
(for N-methoxy-4-nitrobenzamide 1 Sß is 354° as shown by the
reference XRD study).
anism produces aminyl radical A which then gives dimer 4. In
the same manner, N-chloro-N-methoxy-N-tert-alkylamines yield
azoxy compounds by alcoholysis in the presence of Et3N18 and in
reactions with some amines.19 Analogously, methyl N-chloro-
N-methoxycarbamate yields N,N'-bis(methoxycarbonyl)-N,N'-
dimethoxyhydrazine during methanolysis.20,21 This duality of
chemical properties of amide 2 towards the nucleophiles is similar
to that of N-chloro-N-alkoxycarbamates.17,20,21
Thus, in compound 2 the nitrogen pyramidality degree is lower in
comparison with that in N-chloro-N-methoxyurea12 [Sß = 329.0(2)°,
hN = 0.500(1) Å]. Probably this is caused by the bigger degree of
conjugation of Lp of N(1) atom with aroyl group in 2, than that
takes place with carbamoyl group in N-chloro-N-methoxyurea.
This conjugation increases p character of Lp(N1) and shortened
Cl(1)–N(1) bond to 1.7288(14) Å. In N-chloro-N-methoxyurea
the N–Cl bond is longer [1.7563(11) Å12], but in substituted
N-chloro-N-(phenyl)acetamides the N–Cl bond is somewhat
shorter (1.71–1.72 Å).16 The N–OMe bond lengths in amide 2
[1.3967(17) Å] and in N-chloro-N-methoxyurea [1.3984(13) Å]12
are similar to those in N-methoxy-N,N-bis(methoxycarbonyl)imide
[1.396(1) Å]13 and in compound 1 [1.394(5) Å]. In the latter, the
amide nitrogen atom has planar configuration as sp2 hybridized
one. In amide 2 strong pyramidal N(1) atom is sp3 hybridized as
it was predicted earlier.2 The length of Nsp3–OMe bond may be
equal to that of Nsp2–OMe bond only if the former bond is addi-
tionally shortened. Evidently this shortening of Nsp3–OMe bond
in amide 2 is caused by nO(Me) ® s*N–Cl anomeric effect action.
In compound 2 the amide N(1)–C(1) bond is shorter [1.408(2) Å]
than proper amide N–C bond in N-acyloxy-N-alkoxybenzamides6
(1.4394–1.4414 Å, Sß = 323.51°, 324.14°) and in N,N-dialkoxy-
benzamides9,10 [1.45 Å in N-ethoxy-N-methoxy-4-nitrobenzamide
and 1.42 Å in N-methoxy-N-(4-nitrobenzyloxy)benzamide]. In
methyl N-(4-chlorobenzoyloxy)-N-methoxycarbamate the amide
N–C bond is longer as well,11 1.423(2) Å (Sß is 334.1°, hN is
0.426 Å). Shortening amide N–C bond in amide 2 compared with
N–C bond in N-acyloxy-N-alkoxybenzamides,6 N,N-dialkoxy-
benzamides9 and N-acyloxy-N-alkoxycarbamates11 may resulted
from decrease in the N(1) nitrogen pyramidality degree. However,
in amide 1, containing the almost planar amide nitrogen atom, the
proper N–C bond is substantially shorter [1.319(5) Å] compared
with the N(1)–C(1) bond of compound 2.
The structure of N-acetoxy-N-methoxy-4-nitrobenzamide 3§
has been investigated by XRD study (Figure 2). The amide
N(1) atom has large pyramidality degree [Sß = 330.29°, hN
=
= 0.4550(15) Å] which is more compared with that in amide 2,
but less than that in the known N-acyloxy-N-alkoxybenzamides.6
Probably, the last decrease in pyramidality degree is caused by
the action of the 4-nitro group (cf. ref. 6).
The O(1)–N(1) bond [1.3970(18) Å] is shorter than the
O(5)–N(1) bond [1.4214(16) Å] due to nO(Me) ® s*N–O(Ac) anomeric
effect action. This O(1)–N(1) bond length is similar to N–OMe
bond lengths in amide 2, N-acetoxy-N-methoxyurea13 and N-meth-
oxy-N,N-bis(methoxycarbonyl)imide.13 However, in N-benzoyl-
oxy-N-benzyloxybenzamides these differences between lengths
of N–OC(O)R bond and N–OAlk bond are larger.6 In the case
of amide 3 the presence of 4-nitrobenzoyl group at N(1) atom
reduces the action of the nO(Alk) ® s*N–OC(O)R anomeric effect.
The amide N(1)–C(1) bond in 3 is longer [1.4113(19) Å] than
that bond in compound 2. The O(5)–C(9) bond is sp-oriented
§
Crystal data for 1: crystals were grown from CH2Cl2 at –20°C,
C8H8N2O4, monoclinic, space group Pc, a = 3.8578(5), b = 11.8168(16)
and c = 9.6848(12) Å, b = 100.297(11)°, V = 434.38(9) Å3, F(000) = 204,
dcalc = 1.500 g cm–3, Z = 2, m = 0.123 mm–1, M = 196.16.
Crystal data for 2: crystals were grown from CH2Cl2 at –20°C,
–
C8H7N2O4Cl, triclinic, space group P1, a = 6.7596(4), b = 7.8452(6) and
c = 9.6412(6) Å, a = 72.614(6)°, b = 84.737(5)°, g = 73.358(6)°, V =
= 467.47(5) Å3, F(000) = 236, dcalc = 1.638 g cm–3, Z = 4, m = 0.404 mm–1,
M = 230.61.
Crystal data for 3: crystals were grown from CH2Cl2–C6H14 at –20°C,
–
C10H10N2O6, triclinic, space group P1, a = 6.2863(4), b = 8.7528(7) and
c = 11.5095(8) Å, a = 68.848(7)°, b = 84.283(6)°, g = 75.474(6)°, V =
= 571.71(7) Å3, F(000) = 264, dcalc = 1.477 g cm–3, Z = 2, m = 0.124 mm–1,
M = 254.20.
In amide 2 the Lp(N1) is oriented perpendicular to the car-
bonyl group plane [the Lp(N1)–N(1)–C(1)–O(1) torsion angle is
–100°]. The methyl group has sc-orientation toward Lp(N1) [the
Lp(N1)–N(1)–O(2)–C(8) torsion angle is 31°], whereas the aryl
group is slightly turned round to the carbonyl group plane [the
O(1)–C(1)–C(2)–C(7) torsion angle is –30.4(2)°]. The nitro group is
situated in the aryl substituent plane [the O(3)–N(2)–C(5)–C(6)
torsion angle is 3.7(2)°].
Data were measured using an Xcalibur 3 diffractometer [T = 100 K (1
and 2), 180 K (3), graphite-monochromated MoKa radiation, 2q/q scan,
2qmax = 58.04° (1), 65.4° (2), 57.72° (3)]. The structures were solved by
direct method using the SHELXTL PLUS program package.22 Refine-
ment against F2 in an anisotropic approximation (the hydrogen atoms
isotropic in the riding model) by a full matrix least-squares method for
1195 reflections was carried out to wR2 = 0.106 [R1 = 0.054 for 969 reflec-
tions with F > 4s(F), S=1.06] for 1, for 3069 reflections was carried out
to wR2 = 0.112 [R1 = 0.042 for 2597 reflections with F > 4s(F), S = 1.08]
for 2, and for 2588 reflections was carried out to wR2 = 0.095 [R1 = 0.045
for 1713 reflections with F > 4s(F), S = 0.99] for 3.
As other N-chloro-N-alkoxybenzamides,17 compound 2 reacts
with AcONa in MeCN selectively yielding N-acetoxy-N-methoxy-
4-nitrobenzamide 3 by nucleophilic substitution at amide nitrogen
(see Scheme 1). Surprisingly, its methanolysis in the presence of
AcONa afforded only N,N'-bis(4-nitrobenzoyl)-N,N'-dimethoxy-
hydrazine 4. Apparently, reduction of compound 2 by SET-mech-
CCDC 857730–857732 contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
For details, see ‘Notice to Authors’, Mendeleev Commun., Issue 1, 2012.
– 165 –

Mendeleev Commun., 2012, 22, 164–166
10 S. A. Glover, J. M. White, A. A. Rosser and K. M. Digianantonio, J. Org.
towards Lp(N1) [the Lp(N1)–N(1)–O(5)–C(9) torsion angle is
–2°], whereas the C(9)–O(6) carbonyl has sp-orientation towards
N(1)–O(5) bond [the O(6)–C(9)–O(5)–N(1) torsion angle is
–3.4(4)°]. As in compound 2, the O(1)–C(8) bond is sp-oriented
towards Lp(N1) [the Lp(N1)–N(1)–O(1)–C(8) torsion angle is
26°]. The C(1)=O(2) carbonyl group has perpendicular orienta-
tion towards Lp(N1) [the Lp(N1)–N(1)–C(1)–O(2) torsion angle
is –100°]. The aryl group is some turned round to the C(1)=O(2)
carbonyl group [the O(2)–C(1)–C(2)–C(7) torsion angle is
–41.7(2)°].
Chem., 2011, 76, 9757.
11 O. V. Shishkin, R. I. Zubatyuk, V. G. Shtamburg, A. V. Tsygankov, E. A.
Klots,A.V. Mazepa and R. G. Kostyanovsky, Mendeleev Commun., 2006,
222.
12 V. G. Shtamburg, O. V. Shishkin, R. I. Zubatyuk, S. V. Kravchenko, A. V.
Tsygankov, A. V. Mazepa, E. A. Klots and R. G. Kostyanovsky, Mendeleev
Commun., 2006, 323.
13 O. V. Shishkin, V. G. Shtamburg, R. I. Zubatyuk, D. A. Olefir, A. V.
Tsygankov, A. V. Prosyanik, A. V. Mazepa and R. G. Kostyanovsky,
Chirality, 2009, 21, 642.
14 V. G. Shtamburg, O. V. Shishkin, R. I. Zubatyuk, S. V. Kravchenko, A. V.
Tsygankov, V. V. Shtamburg, V. B. Distanov and R. G. Kostyanovsky,
Mendeleev Commun., 2007, 17, 178.
To sum up, XRD study of a representative of N-chloro-N-alkoxy
-
benzamide confirmed the high degree of pyramidality of its amide
nitrogen atom. The influence of electron-withdrawing 4-nitro
substituent in benzoyl group of N-chloro-N-alkoxybenzamides
and N-acyloxy-N-alkoxybenzamides on their structure parameters
and chemical properties has been demonstrated.
15 V. G. Shtamburg, A. V. Tsygankov, M. V. Gerasimenko, O. V. Shishkin,
R. I. Zubatyuk,A.V. Mazepa and R. G. Kostyanovsky, Mendeleev Commun.
2011, 21, 50.
16 S.-Q. Dou, B. T. Gowda, H. Paulus and A. Weiss, Z. Naturforsch., A:
,
Phys. Sci., 1994, 49, 1136.
17 V. G. Shtamburg, E. A. Klots, A. P. Pleshkova, V. I. Avramenko, S. P.
Ivonin, A. V. Tsygankov and R. G. Kostyanovsky, Izv. Akad. Nauk, Ser.
Khim., 2003, 2132 (Russ. Chem. Bull., Int. Ed., 2003, 52, 2251).
18 R. G. Kostyanovsky, V. F. Rudchenko, V. G. Shtamburg, I. I. Chervin and
Sh. S. Nasibov, Tetrahedron, 1981, 37, 4245.
19 V. G. Shtamburg, V. F. Rudchenko, Sh. S. Nasibov, I. I. Chervin and
R. G. Kostyanovsky, Izv. Akad. Nauk SSSR, Ser. Khim., 1981, 2327 (Bull.
Acad. Sci. USSR, Div. Chem. Sci., 1981, 30, 1914).
20 V. G. Shtamburg, V. F. Rudchenko, Sh. S. Nasibov, I. I. Chervin and
R. G. Kostyanovsky, Izv. Akad. Nauk SSSR, Ser. Khim., 1981, 449 (Bull.
Acad. Sci. USSR, Div. Chem. Sci., 1981, 30, 423).
21 V. G. Shtamburg, V. M. Grinev, E. A. Klots and A. V. Tsygankov, Visnyk
Dnipropetrovsk. Univ., Ser. Khimiya, 2005, 11, no. 7, 104 (in Russian).
22 G. M. Sheldrick, Acta Crystallogr., 2008, A64, 112.
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Received: 16th December 2011; Com. 11/3850
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