p-Form­amido­benzoic acid

The title compound, C₈H₇NO₃, is an aromatic amide that forms an extensive hydrogen-bond network within the crystal. The crystals were obtained while preparing derivatives of benzoic acid as intermediaries in the synthesis of acridones.

S1. Comment

The title compound, (I), is an aromatic amide obtained in the final stages in the synthesis of 2-[(4-carboxyphenyl)amino]benzoic acid (Novoa de Armas et al., 2000), which is used as an intermediate in the synthesis of acridones. Crystals of (I) were isolated as pale-yellow plates, possibly formed as a colateral by-product in the reaction of 2-chlorobenzoic acid with 4-aminobenzoic acid in the presence of K₂CO₃, dimethylformamide and copper powder. In previous work on N-aromatic amides, the crystal structures of the amides have been classified into three types according to their scheme of N—H···O═C hydrogen bonds, namely 21, glide and translation (Haisa et al., 1980). The hydrogen-bond pattern in the present structure may be used to corroborate previous works in the systematization of crystal structures of aromatic compounds.

The bond lengths and angles in (I) are similar to those reported for p-amidoperbenzoic acids (Feeder & Jones, 1996) and N-aromatic amides (Kashino et al., 1986). In the crystal, nearly flat molecules lie almost parallel to (010) and extend approximately along a. The dihedral angle between the least-square planes involving the benzene ring (A) and the amide group (B) is 3.3 (1)°. The dihedral angle between the least-square planes involving A and the formyl group (C) is 15.0 (1)° and between planes B and C is 12.9 (1)°. The formyl group is out of the plane formed by A and B. An extensive hydrogen-bond network is formed within the crystal. Hydrogen bonds from the acid proton to the amido carbonyl O atom (O11···O4) are formed by a combination of a c glide and a translation in a. The imido proton is hydrogen bonded to the acid carbonyl O12 atom between molecules related by a and b translations (Fig. 2a). The hydrogen-bond motif forming this two-dimensional network is similar to those observed in p-amidoperbenzoic acids (Feeder & Jones, 1996). An N4—H4···O12 intermolecular hydrogen-bond connects translated molecules into a one-dimensional infinite chain running parallel to the [110] and [110] directions, respectively. The chains are cross-linked by O11—H12···O4 hydrogen bonds, resulting in a three-dimensional network (Fig. 2 b). The hydrogen-bond motifs in the crystal structure can be described using Etter's graph-set notation (Etter et al., 1990) as a first-order network C(10) and a second-order network of the type C₂²(8) C(10), obtained using the RPLUTO program implemented in a recent version of the Cambridge Structural Database (CSD release of April 2000; Allen & Kennard, 1993).

S2. Experimental

During the recrystallization of 2-[(4-carboxyphenyl)amino]benzoic acid (Novoa de Armas et al., 2000) from ethanol–water (1:1), pale-yellow plates of the title compound were obtained.

S3. Refinement

The H atoms were calculated geometrically and included in the refinement, but were restrained to ride on their parent atoms (O—H = 0.82, N—H = 0.86 and C—H = 0.93 Å). The isotropic displacement parameters of the H atoms were fixed to 1.5U_eq of their parent atoms. The absolute structure was not determined as the Flack (1983) parameter was indeterminate [given as 0.0 (4)] due to the lack of sufficient anomalous scatterers.

Computing details

Data collection: XSCANS (Siemens, 1996); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: DIAMOND (Bergerhoff, 1996); software used to prepare material for publication: PLATON (Spek, 1990), PARST (Nardelli, 1983, 1995) and PARSTCIF (Nardelli, 1991).

Figures

	Fig. 1. Plot showing the atomic numbering scheme for (I). Displacement ellipsoids are drawn at the 50% probability level for non-H atoms.
	Fig. 2. Projections of the crystal structure (a) viewed along b and (b) along a showing the cross-linked network.

p-Formamidebenzoic acid

Crystal data

C8H7NO3	F(000) = 172
Mr = 165.15	Dx = 1.491 Mg m^−3
Monoclinic, Pc	Cu Kα radiation, λ = 1.54184 Å
a = 8.0595 (7) Å	Cell parameters from 58 reflections
b = 3.8631 (2) Å	θ = 7.5–27.6°
c = 11.812 (1) Å	µ = 0.98 mm^−1
β = 90.160 (8)°	T = 293 K
V = 367.77 (5) Å^3	Plate, pale-yellow
Z = 2	0.48 × 0.36 × 0.06 mm

Data collection

Siemens P4 four-circle diffractometer	Rint = 0.080
ω/2θ scans	θmax = 69.1°
Absorption correction: ψ scan (North et al., 1968)	h = −1→9
Tmin = 0.609, Tmax = 0.943	k = −1→4
1166 measured reflections	l = −14→14
789 independent reflections	3 standard reflections every 100 reflections
769 reflections with F^2 > 2σ(F^2)	intensity decay: 0.0%

Refinement

Refinement on F^2	H-atom parameters constrained
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0921P)^2 + 0.0348P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.046	(Δ/σ)max = 0.001
wR(F^2) = 0.129	Δρmax = 0.21 e Å^−3
S = 1.13	Δρmin = −0.22 e Å^−3
789 reflections	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin((2θ)]^-1/4
111 parameters	Extinction coefficient: 0.066 (8)

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

	x	y	z	Uiso*/Ueq
C1	−0.2422 (4)	0.1414 (8)	0.9069 (3)	0.0292 (8)*
O11	−0.0396 (3)	0.1018 (7)	1.0496 (2)	0.0490 (8)*
C11	−0.0762 (3)	0.0236 (8)	0.9427 (2)	0.0317 (8)*
O12	0.0174 (3)	−0.1352 (6)	0.8820 (2)	0.0455 (7)*
C2	−0.2933 (3)	0.0814 (9)	0.7959 (3)	0.0309 (9)*
C3	−0.4501 (4)	0.1755 (9)	0.7587 (3)	0.0332 (8)*
O4	−0.7670 (3)	0.1527 (6)	0.6374 (2)	0.0447 (7)*
N4	−0.7195 (3)	0.4428 (7)	0.8037 (2)	0.0345 (8)*
C4	−0.5580 (4)	0.3352 (7)	0.8342 (3)	0.0284 (9)*
C41	−0.8105 (4)	0.3455 (9)	0.7144 (3)	0.036 (1)*
C5	−0.5078 (4)	0.4029 (8)	0.9450 (2)	0.0333 (9)*
C6	−0.3508 (4)	0.3066 (9)	0.9804 (2)	0.0325 (9)*
H11	0.04078	−0.01225	1.07031	0.022 (1)*
H2	−0.22056	−0.02422	0.74558	0.025 (2)*
H3	−0.4828	0.1327	0.6844	0.045*
H4	−0.76522	0.59015	0.84833	0.030 (2)*
H41	−0.9179	0.4328	0.7102	0.042*
H5	−0.57975	0.51235	0.99498	0.029 (1)*
H6	−0.3174	0.3530	1.0543	0.041*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O4	0.0323 (12)	0.0586 (15)	0.0431 (11)	−0.0025 (11)	−0.0128 (10)	−0.0065 (11)
O11	0.0379 (13)	0.0708 (17)	0.0383 (11)	0.0174 (13)	−0.0154 (11)	−0.0042 (11)
O12	0.0298 (11)	0.0614 (15)	0.0453 (12)	0.0136 (11)	−0.0045 (10)	−0.0084 (11)
N4	0.0256 (13)	0.0341 (13)	0.0438 (15)	0.0050 (11)	−0.0061 (11)	−0.0027 (11)
C1	0.0243 (15)	0.0307 (13)	0.0326 (14)	−0.0008 (12)	−0.0049 (13)	−0.0001 (12)
C2	0.0250 (16)	0.0367 (16)	0.0311 (14)	0.0021 (13)	−0.0050 (12)	−0.0019 (13)
C3	0.0308 (15)	0.0383 (16)	0.0304 (13)	0.0015 (14)	−0.0058 (13)	−0.0040 (12)
C4	0.0221 (14)	0.0264 (13)	0.0367 (15)	0.0009 (13)	−0.0077 (12)	0.0026 (13)
C5	0.0302 (15)	0.0378 (16)	0.0319 (15)	0.0047 (13)	−0.0020 (13)	−0.0056 (12)
C6	0.0285 (14)	0.0387 (16)	0.0302 (13)	0.0036 (14)	−0.0069 (12)	−0.0039 (12)
C11	0.0252 (13)	0.0343 (14)	0.0355 (15)	0.0014 (13)	−0.0095 (12)	0.0015 (13)
C41	0.0251 (16)	0.0421 (17)	0.0414 (16)	−0.0016 (13)	−0.0071 (13)	0.0056 (13)

Geometric parameters (Å, º)

C1—C11	1.474 (4)	O4—C41	1.227 (4)
C1—C2	1.393 (4)	N4—H4	0.860
C1—C6	1.389 (4)	N4—C4	1.412 (4)
O11—H11	0.820	N4—C41	1.337 (4)
O11—C11	1.331 (4)	C4—C5	1.394 (4)
C11—O12	1.209 (4)	C41—H41	0.930
C2—H2	0.930	C5—H5	0.930
C2—C3	1.385 (4)	C5—C6	1.383 (4)
C3—H3	0.930	C6—H6	0.930
C3—C4	1.391 (4)
C11—C1—C2	119.0 (3)	H4—N4—C41	115.8
C11—C1—C6	122.4 (3)	C4—N4—C41	128.5 (3)
C2—C1—C6	118.7 (3)	C3—C4—N4	123.0 (3)
H11—O11—C11	109.5	C3—C4—C5	120.3 (3)
C1—C11—O11	113.6 (3)	N4—C4—C5	116.7 (3)
C1—C11—O12	123.6 (3)	O4—C41—N4	126.7 (3)
O11—C11—O12	122.8 (3)	O4—C41—H41	116.7
C1—C2—H2	119.3	N4—C41—H41	116.7
C1—C2—C3	121.5 (3)	C4—C5—H5	120.1
H2—C2—C3	119.3	C4—C5—C6	119.7 (3)
C2—C3—H3	120.5	H5—C5—C6	120.1
C2—C3—C4	118.9 (3)	C1—C6—C5	120.8 (3)
H3—C3—C4	120.5	C1—C6—H6	119.6
H4—N4—C4	115.8	C5—C6—H6	119.6
C2—C1—C11—O11	178.6 (3)	C2—C3—C4—C5	0.8 (4)
C2—C1—C11—O12	−2.8 (5)	H3—C3—C4—N4	−0.5
C6—C1—C11—O11	−2.2 (4)	H3—C3—C4—C5	−179.2
C6—C1—C11—O12	176.3 (3)	H4—N4—C4—C3	−162.4
C11—C1—C2—H2	−2.3	H4—N4—C4—C5	16.4
C11—C1—C2—C3	177.7 (3)	C41—N4—C4—C3	17.6 (5)
C6—C1—C2—H2	178.5	C41—N4—C4—C5	−163.6 (3)
C6—C1—C2—C3	−1.5 (5)	H4—N4—C41—O4	176.1
C11—C1—C6—C5	−177.7 (3)	H4—N4—C41—H41	−3.9
C11—C1—C6—H6	2.3	C4—N4—C41—O4	−3.9 (5)
C2—C1—C6—C5	1.4 (5)	C4—N4—C41—H41	176.1
C2—C1—C6—H6	−178.6	C3—C4—C5—H5	179.2
H11—O11—C11—C1	164.8	C3—C4—C5—C6	−0.8 (4)
H11—O11—C11—O12	−13.8	N4—C4—C5—H5	0.4
C1—C2—C3—H3	−179.6	N4—C4—C5—C6	−179.6 (3)
C1—C2—C3—C4	0.4 (5)	C4—C5—C6—C1	−0.3 (5)
H2—C2—C3—H3	0.4	C4—C5—C6—H6	179.7
H2—C2—C3—C4	−179.6	H5—C5—C6—C1	179.7
C2—C3—C4—N4	179.5 (3)	H5—C5—C6—H6	−0.3

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4···O12^i	0.86	2.09	2.832 (3)	145
O11—H11···O4^ii	0.82	1.82	2.618 (3)	164
C3—H3···O4	0.93	2.36	2.926 (4)	119

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