Benzene-1,4-dicarboxylic acid–N,N-dimethyl­acetamide (1/2)

Abstract

The asymmetric unit of title compound, C₈H₆O₄·2C₄H₉NO, contains one half-mol­ecule (an inversion centre in P21/n generates the other half of the molecule) of terephthalic acid (TA) and one mol­ecule of N,N-dimethyl­acetamide (DMAC). The DMAC mol­ecules are linked to TA by strong O—H⋯O hydrogen bonds.

Related literature

For the crystal structure of terephthalic acid-bis­(N,N-dimethyl­formamide), see: Dale & Elsegood (2004 ▶). For the polymorphism of terephthalic acid, see: Bailey & Brown (1967 ▶); Sledz et al. (2001 ▶).

Experimental

Crystal data

• C₈H₆O₄·2C₄H₉NO

• M _r = 340.37

• Monoclinic,

• a = 10.191 (2) Å

• b = 8.5228 (17) Å

• c = 10.719 (2) Å

• β = 110.67 (3)°

• V = 871.0 (3) ų

• Z = 2

• Mo Kα radiation

• μ = 0.10 mm⁻¹

• T = 113 K

• 0.60 × 0.51 × 0.38 mm

Data collection

• Rigaku R-AXIS RAPID diffractometer

• Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.940, T _max = 0.961

• 6605 measured reflections

• 1522 independent reflections

• 1395 reflections with I > 2σ(I)

• R _int = 0.014

Refinement

• R[F ² > 2σ(F ²)] = 0.043

• wR(F ²) = 0.118

• S = 1.08

• 1522 reflections

• 116 parameters

• H atoms treated by a mixture of independent and constrained refinement

• Δρ_max = 0.58 e Å⁻³

• Δρ_min = −0.26 e Å⁻³

Data collection: RAPID-AUTO (Rigaku, 1998 ▶); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2⋯O1i	0.91 (3)	1.65 (3)	2.551 (2)	173 (2)

Symmetry code: (i) .

supplementary crystallographic information

Comment

Terephthalic acid (TA) is an important intermediate in the production of polyesters for plastics and fiber applications. According to Bailey & Brown (1967), TA exists in two polymorphic modifications (forms 1 and 2), both triclinic. Recently Sledz et al. (2001) reported a new crystalline form of TA which is monoclinic and designated as form 3.

N,N-Dimethylformamide (DMF) and N,N-dimethylacetamide (DMAC) are the two of a few organic solvents capable of dissolving TA. The crystal structure of the 2:1 DMF solvate of terephthalic acid was reported recently (Dale & Elsegood, 2004). The solvent molecules and TA form a centrosymmetric descrete planar assembly with both carboxylic acid groups hydrogen bonded to DMF molecules via R₂²(7) motif (O—H···O/C—H···O interactions). Recently we have obtained single crystals of the DMAC solvate of TA and here we report its crystal structure.

The asymmetric unit of title compound contains one half-molecule of TA and one N, N-dimethyl acetamide (DMAC) molecule (Fig. 2). The DMAC molecules are linked to TA by strong O—H···O hydrogen bonds (Fig.3 and Table 1), which may be effective in stablilizing the crystal structure. The carboxylic group is roughly coplanar with the benzene ring forming dihedral angle of 0.6 (3)° . The dihedral angle between TA and the dimethylacetamide molecule is 21.7 (1)°.

Experimental

Single crystals were obtained by dissolving TA (1.0 g) in DMAC (20 ml) at 80°C and then allowing the solvent to cool to room temperature. The sample proved unstable in the air.

Refinement

The H atom of the carboxylic group was located from a difference Fourier map and fully refined. The remaining H atoms were placed in geometrically calculated positions and refined using a riding model, with U_iso(H) = 1.2 U_eq(C).

Figures

Fig. 1.

View of the title compound showing 50% probability displacement ellipsoids. Symmetry operation for atoms with '#': -x,-y,-z + 1.

Fig. 2.

The packing diagram for the title compound; dashed lines indicate hydrogen bonds.

Crystal data

C8H6O4·2C4H9NO	F(000) = 364
Mr = 340.37	Dx = 1.298 Mg m−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 6873 reflections
a = 10.191 (2) Å	θ = 3.1–27.5°
b = 8.5228 (17) Å	µ = 0.10 mm−1
c = 10.719 (2) Å	T = 113 K
β = 110.67 (3)°	Block, colorless
V = 871.0 (3) Å3	0.60 × 0.51 × 0.38 mm
Z = 2

Data collection

Rigaku R-AXIS RAPID diffractometer	1522 independent reflections
Radiation source: fine-focus sealed tube	1395 reflections with I > 2σ(I)
graphite	Rint = 0.014
Detector resolution: 0 pixels mm-1	θmax = 25.0°, θmin = 3.1°
ω scans	h = −11→11
Absorption correction: multi-scan (ABSCOR; Higashi, 1995)	k = −9→10
Tmin = 0.940, Tmax = 0.961	l = −12→12
6605 measured reflections

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.043	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.118	H atoms treated by a mixture of independent and constrained refinement
S = 1.08	w = 1/[σ2(Fo2) + (0.0571P)2 + 0.6867P] where P = (Fo2 + 2Fc2)/3
1522 reflections	(Δ/σ)max < 0.001
116 parameters	Δρmax = 0.58 e Å−3
0 restraints	Δρmin = −0.26 e Å−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	0.74204 (15)	0.07465 (18)	0.88639 (15)	0.0233 (4)
O1	0.95506 (11)	0.13078 (14)	0.88125 (11)	0.0207 (3)
O2	0.30574 (13)	−0.23616 (15)	0.52621 (12)	0.0248 (3)
O3	0.35578 (12)	−0.10972 (15)	0.72025 (11)	0.0237 (3)
C1	0.89721 (19)	0.2372 (2)	1.06449 (18)	0.0266 (4)
H1A	0.9097	0.1670	1.1378	0.040*
H1B	0.8203	0.3067	1.0557	0.040*
H1C	0.9813	0.2973	1.0806	0.040*
C2	0.86637 (18)	0.1442 (2)	0.93832 (17)	0.0224 (4)
C3	0.71443 (18)	−0.0191 (2)	0.76458 (17)	0.0241 (4)
H3A	0.7248	0.0458	0.6954	0.036*
H3B	0.6206	−0.0598	0.7363	0.036*
H3C	0.7799	−0.1046	0.7824	0.036*
C4	0.63337 (19)	0.0830 (3)	0.9455 (2)	0.0304 (5)
H4A	0.6764	0.0888	1.0408	0.046*
H4B	0.5755	−0.0090	0.9216	0.046*
H4C	0.5768	0.1746	0.9131	0.046*
C5	−0.08828 (17)	−0.03522 (19)	0.37140 (16)	0.0171 (4)
H5	−0.1477	−0.0586	0.2852	0.020*
C6	0.04270 (17)	−0.10394 (19)	0.42154 (16)	0.0175 (4)
H6A	0.0712	−0.1734	0.3692	0.021*
C7	0.13228 (16)	−0.06918 (18)	0.55081 (15)	0.0152 (4)
C8	0.27579 (16)	−0.13973 (18)	0.60876 (15)	0.0163 (4)
H2	0.394 (3)	−0.276 (3)	0.563 (2)	0.052 (7)*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
N1	0.0191 (8)	0.0254 (8)	0.0268 (8)	−0.0007 (6)	0.0097 (6)	0.0006 (6)
O1	0.0166 (6)	0.0255 (7)	0.0209 (6)	−0.0043 (5)	0.0080 (5)	0.0014 (5)
O2	0.0174 (7)	0.0324 (7)	0.0224 (7)	0.0083 (5)	0.0044 (5)	−0.0055 (5)
O3	0.0182 (6)	0.0282 (7)	0.0200 (6)	0.0047 (5)	0.0012 (5)	−0.0035 (5)
C1	0.0258 (9)	0.0256 (10)	0.0299 (10)	−0.0037 (7)	0.0117 (8)	−0.0079 (7)
C2	0.0227 (9)	0.0179 (9)	0.0248 (9)	0.0013 (7)	0.0060 (7)	0.0051 (7)
C3	0.0227 (9)	0.0265 (10)	0.0205 (9)	−0.0061 (7)	0.0047 (7)	−0.0023 (7)
C4	0.0192 (9)	0.0407 (11)	0.0344 (11)	−0.0024 (8)	0.0133 (8)	−0.0086 (8)
C5	0.0168 (8)	0.0189 (8)	0.0145 (8)	−0.0012 (6)	0.0043 (6)	−0.0011 (6)
C6	0.0187 (8)	0.0176 (8)	0.0171 (8)	0.0005 (6)	0.0076 (6)	−0.0018 (6)
C7	0.0140 (8)	0.0156 (8)	0.0170 (8)	−0.0014 (6)	0.0066 (6)	0.0022 (6)
C8	0.0164 (8)	0.0159 (8)	0.0175 (8)	−0.0009 (6)	0.0072 (6)	0.0017 (6)

Geometric parameters (Å, °)

N1—C2	1.330 (2)	C3—H3B	0.9600
N1—C4	1.459 (2)	C3—H3C	0.9600
N1—C3	1.471 (2)	C4—H4A	0.9600
O1—C2	1.263 (2)	C4—H4B	0.9600
O2—C8	1.320 (2)	C4—H4C	0.9600
O2—H2	0.91 (3)	C5—C6	1.381 (2)
O3—C8	1.213 (2)	C5—C7i	1.397 (2)
C1—C2	1.502 (2)	C5—H5	0.9300
C1—H1A	0.9600	C6—C7	1.396 (2)
C1—H1B	0.9600	C6—H6A	0.9300
C1—H1C	0.9600	C7—C5i	1.397 (2)
C3—H3A	0.9600	C7—C8	1.498 (2)
C2—N1—C4	123.61 (16)	N1—C4—H4A	109.5
C2—N1—C3	117.98 (15)	N1—C4—H4B	109.5
C4—N1—C3	118.39 (14)	H4A—C4—H4B	109.5
C8—O2—H2	111.4 (16)	N1—C4—H4C	109.5
C2—C1—H1A	109.5	H4A—C4—H4C	109.5
C2—C1—H1B	109.5	H4B—C4—H4C	109.5
H1A—C1—H1B	109.5	C6—C5—C7i	120.51 (15)
C2—C1—H1C	109.5	C6—C5—H5	119.7
H1A—C1—H1C	109.5	C7i—C5—H5	119.7
H1B—C1—H1C	109.5	C5—C6—C7	119.99 (15)
O1—C2—N1	119.73 (16)	C5—C6—H6A	120.0
O1—C2—C1	121.74 (15)	C7—C6—H6A	120.0
N1—C2—C1	118.53 (16)	C6—C7—C5i	119.50 (15)
N1—C3—H3A	109.5	C6—C7—C8	121.80 (15)
N1—C3—H3B	109.5	C5i—C7—C8	118.70 (14)
H3A—C3—H3B	109.5	O3—C8—O2	123.91 (15)
N1—C3—H3C	109.5	O3—C8—C7	122.83 (15)
H3A—C3—H3C	109.5	O2—C8—C7	113.26 (14)
H3B—C3—H3C	109.5

Symmetry codes: (i) −x, −y, −z+1.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
O2—H2···O1ii	0.91 (3)	1.65 (3)	2.551 (2)	173 (2)

Symmetry codes: (ii) −x+3/2, y−1/2, −z+3/2.