4,6-Dinitro-N,N′-di-n-octylbenzene-1,3-diamine, 4,6-dinitro-N, N′-di-n-undecyl-benzene-1,3-diamine and N,N′-bis-(2,4-dinitro-phen- yl)octane-1,8-diamine

Article abstract of DOI:10.1107/S0108270109001619

4,6-Dinitro-N,N′-di-n-octylbenzene-1,3-diamine, C22H ₃8N4O₄, (I), 4,6-dinitro-N,N′-di-n-undecyl-benzene- 1,3-diamine, C28H₅0N4O₄, (II), and N,N′-bis-(2,4- dinitro-phenyl)octane-1,8-diamine, C20H₂4N6O8

Full text of DOI:10.1107/S0108270109001619

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
polymer repeat units (Teng et al., 2006). These polymers were
prepared by the reactions of various aliphatic diamines
with 1,5-difluoro-2,4-dinitrobenzene (DFDNB) in dimethyl-
acetamide (DMAC) and diphenyl sulfone (DPS) at elevated
temperatures. Anhydrous potassium carbonate was used as
the acid scavenger and the resulting by-product, viz. water,
was removed by toluene via azeotropic distillation. The
aforementioned reaction conditions, in particular the need for
higher reaction temperatures to achieve high molecular
weight polymers, were ascertained from the preparation of
various model compounds. For example, the higher degree
of solubility of 4,6-dinitro-N,N0-di-n-octylbenzene-1,3-di-
amine, (I), in DMAC, in contrast with N,N0-bis(2,4-dinitro-
phenyl)octane-1,8-diamine, (III), which precipitates out of
refluxing DMAC, led us to use DPS (a higher boiling point
dipolar aprotic solvent) as co-solvent during polymer synth-
eses. The prepared polymers were soluble only in strong
mineral acids with bulky counter-ions, including nitric, sulfuric
and perchloric acids at room temperature. This exceptional
solvent resistance can be attributed to both inter- and intra-
chain hydrogen bonding and possible hydrophobic inter-
actions. In addition, the chain flexibility associated with longer
aliphatic chains (hexyl and higher) allows for semihelical
chains, which further facilitates a higher order of chain
packing. This was evidenced from the complex wide-angle
X-ray data for these polymers. Notwithstanding these strong
interactions, it is possible to obtain fingernail-creasable films
by compression-molding these polymers above their melting
points. This paper is part of our continuing study of the
structures of the monomer units for these polymers (Walczak
et al., 2008). Compounds (I), (II) (4,6-dinitro-N,N0-di-n-
undecylbenzene-1,3-diamine) and (III) constitute a new
family of dinitroarenes functionalized with long-chain alkyl
amines. These model compounds and their intermolecular
interactions offer insight into the physical properties of
polymers prepared from diamines and the corresponding
difluoro compound.
ISSN 0108-2701
4,6-Dinitro-N,N0-di-n-octylbenzene-
1,3-diamine, 4,6-dinitro-N,N0-di-n-
undecylbenzene-1,3-diamine and
N,N0-bis(2,4-dinitrophenyl)octane-
1,8-diamine
Gary Teng,a Christopher P. Walczak,a Philip J.
Squattrito,a* Dillip K. Mohanty,a* William Scharer,b
Mark R. Giolandob and Kristin Kirschbaumb
aDepartment of Chemistry, Central Michigan University, Mount Pleasant, MI 48859,
USA, and bDepartment of Chemistry, University of Toledo, Toledo, OH 43606, USA
Correspondence e-mail: p.squattrito@cmich.edu, mohan1dk@cmich.edu
Received 9 January 2009
Accepted 13 January 2009
Online 17 January 2009
4,6-Dinitro-N,N0-di-n-octylbenzene-1,3-diamine, C22H38N4O4,
(I), 4,6-dinitro-N,N0-di-n-undecylbenzene-1,3-diamine, C28H50-
N4O4, (II), and N,N0-bis(2,4-dinitrophenyl)octane-1,8-diamine,
C20H24N6O8, (III), are the first synthetic meta-dinitroarenes
functionalized with long-chain aliphatic amine groups to be
structurally characterized. The intra- and intermolecular
interactions in these model compounds provide information
that can be used to help understand the physical properties
of corresponding polymers with similar functionalities.
Compounds (I) and (II) possess near-mirror symmetry, with
the octyl and undecyl chains adopting fully extended anti
conformations in the same direction with respect to the ring.
Compound (III) rests on a center of inversion that occupies
the mid-point of the central C—C bond of the octyl chain. The
middle six C atoms of the chain form an anti arrangement,
while the remaining two C atoms take hard turns almost
perpendicular to the rest of the chain. All three molecules
display intramolecular N—Hꢀ ꢀ ꢀO hydrogen bonds between
the amine and nitro groups, with the same NH group forming a
bifurcated intermolecular hydrogen bond to the nitro O atom
of an adjacent molecule. In each case, these interactions link
the molecules into one-dimensional molecular chains. In (I)
and (II), these chains pack so that the pendant alkyl groups
are interleaved parallel to one another, maximizing non-
bonded C—H contacts. In (III), the alkyl groups are more
isolated within the molecular chains and the primary non-
bonded contacts between the chains appear to involve the
nitro groups not involved in the hydrogen bonding.
Molecules of (I) come close to having an internal mirror
plane but in fact reside on general positions (Fig. 1). The H
atoms on the N atoms of the n-octylamine groups participate
in strong intramolecular hydrogen bonds with the O atoms of
the adjacent nitro group (Table 1). This pattern has been
Comment
We have recently reported the preparation and characteristics
of polyamines containing two aromatic nitro groups in the
o76 # 2009 International Union of Crystallography
doi:10.1107/S0108270109001619
Acta Cryst. (2009). C65, o76–o80

organic compounds
Figure 1
The molecular structure of (I), showing the atom-numbering scheme.
Displacement ellipsoids are drawn at the 50% probability level and H
atoms are shown as small spheres of arbitrary radii. Intramolecular
hydrogen bonds are shown as dashed bonds.
Figure 3
The molecular structure of (II), showing the atom-numbering scheme.
Displacement ellipsoids are drawn at the 50% probability level and H
atoms are shown as small spheres of arbitrary radii. Intramolecular
hydrogen bonds are shown as dashed lines.
Figure 2
Figure 4
Portions of two adjacent molecular chains of (I) that run approximately
parallel to (120), viewed along the a axis. Intra- and intermolecular
N—Hꢀ ꢀ ꢀO hydrogen bonds are shown as dashed bonds.
Portions of two adjacent molecular chains of (II) that run approximately
parallel to (120), viewed along the a axis. Intra- and intermolecular
N—Hꢀ ꢀ ꢀO hydrogen bonds are shown as dashed lines.
ving nitro O atoms from different molecules has been
observed before (Panunto et al., 1987), but it appears to be
more commonly associated with the formation of isolated
dimers (akin to the behavior of carboxylic acid groups) rather
than chains. The linking of amine- and nitro-substituted
organic molecules into chains is more commonly accomplished
by bifurcated hydrogen bonds in which the N—H group of one
molecule interacts with two O atoms from the same nitro
group of an adjacent molecule (Panunto et al., 1987). In the
crystal structure of (I) described here, the chains are formed
such that the octyl groups of adjacent molecules point to
opposite sides of the chain. As a result, when the chains pack
in the c direction, the octyl groups interleave, thus forming
hydrophobic domains dominated by C—H interactions. In
addition, the arene rings are stacked on top of each other
observed previously in molecules with primary amine groups
on both sides of a nitro group (Ammon et al., 1982). A search
of the Cambridge Structural Database (Version 5.29 plus
updates in January 2008 and August 2008; Allen, 2002) reveals
three structures of 1,5-bis(amino)-substituted 2,4-dinitro-
benzene derivatives with 3-amino-1-pentanoic acid (Williams
et al., 1993), hydroxyethylamine (Lee et al., 2006) and
3-(2,2,5,5-tetramethylpyrrolidinyl N-oxide)amine (Hilti et al.,
1976) groups, respectively, that display the same intra-
molecular N—Hꢀ ꢀ ꢀO hydrogen bonding. In these other cases,
the amine functional groups contain strong hydrogen-bonding
donors and/or acceptors which create very different inter-
molecular interactions. Compound (I) is the first example we
are aware of in which the amine functional groups are long
alkyl chains with no additional substitution.
˚
The octyl groups in (I) adopt an anti conformation
throughout the chain. However, unlike what was observed in
1,3-bis(n-octylamino)-2-nitrobenzene (Walczak et al., 2008),
the chains are not coplanar with the ring. Rather, the axis of
the parallel chains in (I) is roughly 38ꢁ out of the plane
containing the ring, nitro groups and amine N atoms. This
difference is most likely associated with the formation of
intramolecular N—Hꢀ ꢀ ꢀO interactions in (I) that are not
observed in 1,3-bis(n-octylamino)-2-nitrobenzene. These H
atoms are further involved in bifurcated intermolecular
interactions (Table 1) that link the molecules of (I) into chains
that run in the [210] direction and stack parallel to (120)
(Fig. 2). This type of bifurcated N—Hꢀ ꢀ ꢀO interaction invol-
along the a axis at distances of ca 3.8–3.9 A apart. This is also
different from what was found for 1,3-bis(n-octylamino)-2-
nitrobenzene (Walczak et al., 2008).
Molecules of (II) adopt essentially the same molecular
structure as those of (I), with the alkyl chains simply extended
by three methylene groups (Fig. 3). Intramolecular N—Hꢀ ꢀ ꢀO
amine–nitro hydrogen bonds occur on both sides of the ring
(Table 2), the undecyl chains are in the anti conformation for
the length of the chain and the parallel chains are canted by ca
36ꢁ with respect to the plane of the arene ring. The packing in
the ab plane is virtually identical to that in (I), as indicated by
the similarity of the cell dimensions, with the same inter-
molecular hydrogen-bonding pattern and interleaving of the
ꢂ
Acta Cryst. (2009). C65, o76–o80
Teng et al.
C22H38N4O4, C28H50N4O4 and C20H24N6O8 o77

organic compounds
Because each molecule can form two such bifurcated inter-
actions, the net result is a motif of chains running along the c
direction (Fig. 6). These chains then stack along the b direc-
tion, with the nitro groups that are not involved in the
hydrogen bonds in close proximity to one another. Contrary to
(I) and (II), the packing in (III) does not cleanly maximize
contacts between either the alkyl chains or the arene rings. We
believe that this is the first N,N0-(2,4-dinitrophenyl)alkane-
diamine to be structurally characterized.
Figure 5
The molecular structure of (III), showing the atom-numbering scheme.
Displacement ellipsoids are drawn at the 50% probability level and H
atoms are shown as small spheres of arbitrary radii. Intramolecular
hydrogen bonds are shown as dashed lines. The asymmetric unit consists
of one half-molecule, and unlabeled atoms are related to labeled atoms
by the symmetry operator (1 ꢃ x, 1 ꢃ y, ꢃz).
Experimental
For the preparation of (I), octylamine (1.29 g, 0.01 mol), 1,5-difluoro-
2,4-dinitrobenzene (DFDNB) (1.02 g, 0.005 mol), anhydrous potas-
sium carbonate (2.20 g, excess), dimethylacetamide (DMAC) (20 ml)
and toluene (15 ml) were placed in a four-necked 100 ml round-
bottomed flask fitted with a thermometer, a nitrogen inlet, an over-
head stirrer and a Dean–Stark trap fitted with a condenser. The
reaction vessel was heated by an external oil bath to an initial
temperature of 333 K and the reaction was allowed to continue at this
temperature, with stirring, for 30 min. The temperature of the reac-
tion mixture was gradually raised to 423 K over a period of 2 h.
Water, the by-product of the reaction mixture, was removed by
azeotropic distillation with toluene. After complete removal of water,
the reaction mixture was cooled to room temperature, diluted with
tetrahydrofuran (25 ml), filtered, and the filtrate poured into a
rapidly stirred water–acetic acid mixture (1:1 v/v). The crude yellow
precipitate was isolated by filtration and washed with a saturated
sodium bicarbonate solution to remove residual acetic acid. The
product was air-dried under suction overnight, dissolved in di-
chloromethane and washed twice with water, and the organic layer
was dried over anhydrous magnesium sulfate. It was then filtered and
the volume of the solution was reduced using a rotary evaporator.
Compound (I) was then allowed to crystallize from the concentrated
solution [yield 80%, m.p. 355 K (differential scanning calorimetry)].
1H NMR (400 MHz, CDCl3): ꢀ 9.17 (d, 1H), 8.28 (t, 2H), 5.60 (s, 1H),
3.25 (m, 4H), 1.75 (m, 4H), 1.36 (m, 20H), 1.05 (t, 6H); 13C NMR
(CDCl3): ꢀ 148.78, 129.75, 124.18, 90.22, 43.59, 32.00, 29.47, 29.39,
28.67, 27.33, 22.87, 14.32; IR (KBr, ꢁ > 1400 cmꢃ1): 3379, 2921, 2847,
1616, 1581, 1542, 1411; MS (m/z) (% base peak): 422 (18), 387 (100),
323 (75), 305 (36).
Figure 6
Portions of two adjacent molecular chains of (III) running along the c
direction, viewed along the a axis. Intra- and intermolecular N—Hꢀ ꢀ ꢀO
hydrogen bonds are shown as dashed lines.
alkyl chains (Fig. 4). As a result of the additional methylene
˚
units, the c axis of (II) is about 4 A longer than that of (I).
Compound (II) was prepared by a similar procedure [yield 78%,
1
m.p. 365 K (differential scanning calorimetry)]. H NMR (400 MHz,
Molecules of (III) possess internal inversion symmetry
about the center of the C10—C10i bond [symmetry code: (i)
1 ꢃ x, 1 ꢃ y, ꢃz] (Fig. 5). The amine H atom participates in an
intramolecular hydrogen bond with the nearest nitro O atom
(Table 3). The majority of the octyl chain forms an extended
anti conformation (torsion angles all within 4ꢁ of 180ꢁ).
However, the last C atom at each end is gauche to the rest of
the chain (C10—C9—C8—C7 torsion angle ca 71ꢁ). As a
result, although the planes of the arene rings are parallel, they
are not coplanar. The octyl chain forms a modified S-shaped
connector between the rings. This conformation gives support
to the proposition that polymer chains made from this
monomer could have semihelical arrangements.
CDCl3): ꢀ 9.24 (d, 1H), 8.33 (t, 2H), 5.64 (s, 1H), 3.27 (m, 4H), 1.77 (m,
4H), 1.38 (m, 32H), 0.88 (t, 6H); 13C NMR (CDCl3): ꢀ 148.51, 129.50.
123.91, 90.50, 43.31, 31.86, 29.56, 29.53, 29.46, 29.29, 29.24, 28.39,
27.05, 22.64, 14.07; IR (KBr, ꢁ > 1400 cmꢃ1): 3379, 2916, 2848, 1618,
1581, 1411, 1254; MS (m/z) (% base peak): 506 (11), 471 (100),
389 (24), 365 (29).
Compound (III) was prepared from octane-1,8-diamine and two
equivalents of 2,4-dinitrofluorobenzene using a similar reaction
procedure. However, the resulting compound was sparingly soluble in
DMAC at its reflux temperature. The reaction mixture was cooled to
room temperature and then filtered. The residue was purified using a
Soxhlet apparatus. Acetone, water and acetone, in that order, were
used to remove residual salts and DMAC. The crude product was
dried and recrystallized from refluxing trichloromethane to obtain
suitable crystals for X-ray analysis [yield 75%, m.p. 415 K (differ-
ential scanning calorimetry)]. 1H NMR (400 MHz, D2SO4): ꢀ 8.6 (m,
1H), 8.1 (m, 1H), 5.6 (s, 1H), 7.4 (m, 1H), 3.0 (t, 2H), 1.2 (m, 2H),
0.9 (m, 4H); 13C NMR (D2SO4): ꢀ 147.08, 139.45, 132.60, 131.02,
Similarly to the case in (I) and (II), the molecules of (III)
are linked by four-center hydrogen bonds involving two amine
H atoms and two nitro O atoms, the same groups being
involved in the intramolecular N—Hꢀ ꢀ ꢀO interactions.
ꢂ
o78 Teng et al. C22H38N4O4, C28H50N4O4 and C20H24N6O8
Acta Cryst. (2009). C65, o76–o80

organic compounds
127.20, 122.30, 54.90, 26.67, 24.61, 23.98; IR (KBr, ꢁ > 1400 cmꢃ1):
3363, 1621, 1585, 1522, 1420; MS (m/z) (% base peak): 476 (2),
264 (12), 196 (100), 180 (55).
Table 1
Hydrogen-bond geometry (A, ) for (I).
ꢁ
˚
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
N3—H3Nꢀ ꢀ ꢀO1
N3—H3Nꢀ ꢀ ꢀO1i
N4—H4Nꢀ ꢀ ꢀO3
N4—H4Nꢀ ꢀ ꢀO3ii
0.843 (16)
0.843 (16)
0.799 (17)
0.799 (17)
2.008 (16)
2.354 (16)
2.027 (17)
2.312 (17)
2.6535 (13)
3.0166 (12)
2.6412 (14)
2.9647 (13)
132.7 (14)
135.8 (14)
133.5 (15)
139.3 (15)
Compound (I)
Crystal data
C22H38N4O4
Mr = 422.56
Triclinic, P1
ꢄ = 86.421 (1)ꢁ
V = 1138.49 (8) A
Z = 2
Mo Kꢂ radiation
ꢅ = 0.09 mmꢃ1
T = 120 (2) K
0.38 ꢄ 0.12 ꢄ 0.05 mm
Symmetry codes: (i) ꢃx þ 1; ꢃy; ꢃz; (ii) ꢃx ꢃ 1; ꢃy þ 1; ꢃz.
3
˚
˚
a = 4.6679 (2) A
˚
b = 15.5897 (6) A
Table 2
Hydrogen-bond geometry (A, ) for (II).
˚
c = 15.7690 (6) A
ꢁ
˚
ꢂ = 83.760 (1)ꢁ
ꢃ = 89.356 (1)ꢁ
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
N3—H3Nꢀ ꢀ ꢀO1
N3—H3Nꢀ ꢀ ꢀO1i
N4—H4Nꢀ ꢀ ꢀO3
N4—H4Nꢀ ꢀ ꢀO3ii
0.89 (2)
0.89 (2)
0.80 (2)
0.80 (2)
1.95 (2)
2.42 (2)
2.01 (2)
2.39 (2)
2.6456 (19)
3.0927 (19)
2.646 (2)
134 (2)
Data collection
132.5 (18)
135.9 (19)
140.3 (18)
Bruker SMART 6000 CCD area-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.866, Tmax = 0.996
20817 measured reflections
5647 independent reflections
4846 reflections with I > 2ꢆ(I)
Rint = 0.027
3.048 (2)
Symmetry codes: (i) ꢃx þ 3; ꢃy þ 1; ꢃz; (ii) ꢃx þ 1; ꢃy þ 2; ꢃz.
Table 3
Hydrogen-bond geometry (A, ) for (III).
Refinement
ꢁ
˚
R[F2 > 2ꢆ(F2)] = 0.044
wR(F2) = 0.116
S = 1.06
423 parameters
All H-atom parameters refined
D—Hꢀ ꢀ ꢀA
D—H
Hꢀ ꢀ ꢀA
Dꢀ ꢀ ꢀA
D—Hꢀ ꢀ ꢀA
ꢃ3
˚
Áꢇmax = 0.38 e A
ꢃ3
˚
5647 reflections
Áꢇmin = ꢃ0.23 e A
N3—H3ꢀ ꢀ ꢀO1
0.85 (2)
0.85 (2)
2.00 (2)
2.28 (2)
2.6382 (18)
3.0202 (18)
131.9 (18)
146.3 (18)
N3—H3ꢀ ꢀ ꢀO1i
Symmetry code: (i) ꢃx þ 1; ꢃy þ 1; ꢃz þ 1.
Compound (II)
Crystal data
Data collection
C28H50N4O4
Mr = 506.72
Triclinic, P1
ꢄ = 87.069 (2)ꢁ
V = 1459.44 (5) A
Z = 2
Mo Kꢂ radiation
ꢅ = 0.08 mmꢃ1
T = 293 (2) K
0.41 ꢄ 0.06 ꢄ 0.01 mm
3
˚
Bruker SMART 6000 CCD area-
detector diffractometer
Absorption correction: multi-scan
(SADABS; Sheldrick,1996)
Tmin = 0.759, Tmax = 0.986
8443 measured reflections
2096 independent reflections
1973 reflections with I > 2ꢆ(I)
Rint = 0.026
˚
a = 4.7349 (1) A
˚
b = 15.6273 (3) A
˚
c = 19.7771 (3) A
ꢂ = 87.282 (2)ꢁ
ꢃ = 88.549 (2)ꢁ
Refinement
R[F2 > 2ꢆ(F2)] = 0.044
wR(F2) = 0.109
S = 1.11
202 parameters
All H-atom parameters refined
Data collection
ꢃ3
˚
Áꢇmax = 0.34 e A
Rigaku RAPID diffractometer
Absorption correction: empirical
(using intensity measurements)
(D*TREK; Pflugrath, 1999)
Tmin = 0.822, Tmax = 1.000
22872 measured reflections
5726 independent reflections
4432 reflections with I > 2ꢆ(I)
Rint = 0.028
ꢃ3
˚
2096 reflections
Áꢇmin = ꢃ0.24 e A
All H atoms were located from difference Fourier syntheses and
refined isotropically [for all compounds, arene C—H = 0.89 (2)–
(expected range = 0.821–0.999)
˚
0.94 (2) A and alkyl C—H = 0.94 (4)–1.04 (2) A].
˚
Refinement
Data collection: SMART (Bruker, 2003) for (I) and (III); Crystal
Clear (Rigaku, 2002) for (II). Cell refinement: SAINT-Plus (Bruker,
2003) for (I) and (III); D*TREK (Pflugrath, 1999) for (II). Data
reduction: SAINT-Plus for (I) and (III); D*TREK for (II). For all
three compounds, program(s) used to solve structure: SHELXS97
(Sheldrick, 2008); program(s) used to refine structure: SHELXL97
(Sheldrick, 2008); molecular graphics: CrystalMaker (Palmer, 2008);
software used to prepare material for publication: SHELXL97.
R[F2 > 2ꢆ(F2)] = 0.058
wR(F2) = 0.176
S = 1.11
525 parameters
All H-atom parameters refined
ꢃ3
˚
Áꢇmax = 0.17 e A
ꢃ3
˚
5726 reflections
Áꢇmin = ꢃ0.24 e A
Compound (III)
Crystal data
3
˚
V = 1069.75 (5) A
Z = 2
C20H24N6O8
Mr = 476.45
DKM acknowledges financial support for this project from
the President’s Research Investment Fund and the President’s
Bridge to Commercialization Grant, and sabbatical support
from Central Michigan University. The authors thank the
College of Arts and Sciences of the University of Toledo and
Monoclinic, P21=c
Mo Kꢂ radiation
ꢅ = 0.12 mmꢃ1
T = 105 (2) K
0.30 ꢄ 0.20 ꢄ 0.12 mm
˚
a = 4.6740 (1) A
˚
b = 25.7389 (8) A
˚
c = 8.9254 (3) A
ꢃ = 94.949 (1)ꢁ
ꢂ
Acta Cryst. (2009). C65, o76–o80
Teng et al.
C22H38N4O4, C28H50N4O4 and C20H24N6O8 o79

organic compounds
Hilti, E., Ottersen, T. & Seff, K. (1976). J. Cryst. Mol. Struct. 6, 87–100.
Lee, S. C., Jeong, Y. G., Jo, W. H., Kim, H.-J., Jang, J., Park, K.-M. & Chung,
I. H. (2006). J. Mol. Struct. 825, 70–78.
the Ohio Board of Regents for generous financial support of
the X-ray diffraction facility.
Palmer, D. (2008). CrystalMaker. Version 8.1. CrystalMaker Software Ltd,
Yarnton, England.
Panunto, T. W., Urbanczyk-Lipkowska, Z., Johnson, R. & Etter, M. C. (1987).
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archives (Reference: SK3288). Services for accessing these data are
described at the back of the journal.
Rigaku (2002). CrystalClear. Version 1.3.6. Rigaku Corporation, Tokyo, Japan.
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