4-Amino-2-chloro-benzoic acid.

The title compound, C(7)H(6)ClNO(2), crystallizes with two roughly planar mol-ecules in the asymmetric unit (r.m.s. deviations = 0.073 and 0.074 Å). The amine H atoms of the two mol-ecules have opposite orientations. In the crystal, mol-ecules are linked into dimers by pairs of O-H⋯O hydrogen bonds, generating R(2) (2)(8) loops. N-H⋯N and N-H⋯Cl hydrogen bonds link the dimers into a three-dimensional network. The crystal studied was found to be a racemic twin.

Related literature

For an isomer (2-amino-4-chloro­benzoic acid) of the title compound, see: Farag et al. (2011 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C7H6ClNO2

M = 171.58

Monoclinic,

a = 3.9595 (2) Å

b = 22.6656 (11) Å

c = 8.0285 (4) Å

β = 104.257 (2)°

V = 698.32 (6) Å3

Z = 4

Mo Kα radiation

μ = 0.49 mm−1

T = 296 K

0.28 × 0.13 × 0.12 mm

Data collection

Bruker APEXII CCD diffractometer

3009 measured reflections

2295 independent reflections

2197 reflections with I > 2σ(I)

R int = 0.011

Refinement

R[F 2 > 2σ(F 2)] = 0.029

wR(F 2) = 0.077

S = 1.07

2295 reflections

218 parameters

7 restraints

H atoms treated by a mixture of independent and constrained refinement

Δρmax = 0.21 e Å−3

Δρmin = −0.23 e Å−3

Absolute structure: Flack (1983 ▶), 514 Freidel pairs

Flack parameter: 0.50 (6)

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶) and PLATON (Spek, 2009 ▶).

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536811030728/hb6334sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811030728/hb6334Isup2.hkl

Supplementary material file. DOI: 10.1107/S1600536811030728/hb6334Isup3.cml

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

C7H6ClNO2	F(000) = 352
Mr = 171.58	Dx = 1.632 Mg m−3
Monoclinic, P21	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2yb	Cell parameters from 3211 reflections
a = 3.9595 (2) Å	θ = 2.8–28.3°
b = 22.6656 (11) Å	µ = 0.49 mm−1
c = 8.0285 (4) Å	T = 296 K
β = 104.257 (2)°	Prism, reddish brown
V = 698.32 (6) Å3	0.28 × 0.13 × 0.12 mm
Z = 4

Bruker APEXII CCD diffractometer	2197 reflections with I > 2σ(I)
Radiation source: sealed tube	Rint = 0.011
graphite	θmax = 28.3°, θmin = 2.8°
φ and ω scans	h = −5→5
3009 measured reflections	k = −18→30
2295 independent reflections	l = −10→10

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.029	H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.077	w = 1/[σ2(Fo2) + (0.0454P)2 + 0.092P] where P = (Fo2 + 2Fc2)/3
S = 1.07	(Δ/σ)max < 0.001
2295 reflections	Δρmax = 0.21 e Å−3
218 parameters	Δρmin = −0.23 e Å−3
7 restraints	Absolute structure: Flack (1983), 514 Freidel pairs
Primary atom site location: structure-invariant direct methods	Flack parameter: 0.50 (6)

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating -R-factor-obs 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.

	x	y	z	Uiso*/Ueq
Cl1	0.23950 (15)	0.81998 (3)	0.56801 (6)	0.0427 (2)
O1	−0.2726 (5)	0.65233 (9)	0.6710 (2)	0.0502 (6)
O2	−0.0913 (6)	0.70711 (10)	0.4820 (2)	0.0577 (7)
N1	0.5447 (5)	0.83421 (11)	1.2139 (3)	0.0431 (7)
C1	0.2193 (5)	0.78948 (10)	0.7631 (3)	0.0277 (5)
C2	0.3803 (5)	0.82200 (12)	0.9065 (3)	0.0316 (5)
C3	0.3834 (5)	0.80158 (10)	1.0704 (3)	0.0306 (6)
C4	0.2106 (6)	0.74934 (11)	1.0871 (3)	0.0349 (6)
C5	0.0515 (6)	0.71758 (11)	0.9432 (3)	0.0338 (6)
C6	0.0508 (5)	0.73617 (10)	0.7767 (3)	0.0294 (6)
C7	−0.1085 (5)	0.69776 (11)	0.6301 (3)	0.0341 (6)
Cl2	0.80948 (15)	0.96180 (3)	0.66956 (7)	0.0442 (2)
O3	0.3027 (6)	1.13060 (8)	0.7718 (2)	0.0511 (6)
O4	0.4834 (7)	1.07555 (10)	0.5823 (2)	0.0581 (7)
N2	1.1098 (6)	0.94780 (12)	1.3131 (3)	0.0491 (8)
C8	0.7883 (5)	0.99282 (10)	0.8643 (3)	0.0293 (5)
C9	0.9466 (5)	0.96044 (12)	1.0074 (3)	0.0321 (5)
C10	0.9516 (5)	0.98080 (11)	1.1714 (3)	0.0349 (6)
C11	0.7808 (6)	1.03355 (12)	1.1881 (3)	0.0356 (6)
C12	0.6218 (6)	1.06497 (11)	1.0437 (3)	0.0347 (6)
C13	0.6238 (5)	1.04643 (10)	0.8776 (3)	0.0295 (6)
C14	0.4640 (5)	1.08498 (11)	0.7309 (3)	0.0336 (6)
HO1	−0.335 (8)	0.6315 (13)	0.585 (3)	0.0640*
H2	0.48700	0.85770	0.89330	0.0380*
HN1	0.607 (7)	0.8126 (13)	1.303 (3)	0.0510*
HN2	0.707 (6)	0.8583 (11)	1.203 (4)	0.0510*
H4	0.20270	0.73590	1.19550	0.0420*
H5	−0.05990	0.68240	0.95690	0.0410*
HO3	0.220 (8)	1.1532 (14)	0.694 (4)	0.0660*
HN3	1.163 (7)	0.9675 (13)	1.407 (3)	0.0530*
HN4	1.262 (6)	0.9232 (11)	1.296 (4)	0.0530*
H9	1.05120	0.92460	0.99420	0.0390*
H11	0.77480	1.04740	1.29640	0.0430*
H12	0.50820	1.09990	1.05690	0.0420*

	U11	U22	U33	U12	U13	U23
Cl1	0.0554 (3)	0.0449 (3)	0.0274 (2)	−0.0095 (3)	0.0097 (2)	0.0044 (2)
O1	0.0723 (11)	0.0413 (11)	0.0365 (9)	−0.0205 (9)	0.0123 (8)	−0.0066 (8)
O2	0.0901 (14)	0.0528 (12)	0.0312 (8)	−0.0299 (11)	0.0170 (9)	−0.0109 (9)
N1	0.0473 (10)	0.0514 (15)	0.0276 (9)	−0.0042 (9)	0.0033 (8)	−0.0061 (9)
C1	0.0280 (8)	0.0302 (11)	0.0252 (9)	0.0023 (8)	0.0073 (7)	0.0022 (8)
C2	0.0313 (8)	0.0335 (11)	0.0290 (9)	0.0005 (9)	0.0058 (7)	−0.0018 (10)
C3	0.0292 (8)	0.0340 (12)	0.0281 (9)	0.0038 (8)	0.0061 (7)	−0.0020 (8)
C4	0.0407 (10)	0.0384 (13)	0.0267 (10)	0.0060 (9)	0.0103 (9)	0.0025 (9)
C5	0.0384 (10)	0.0301 (12)	0.0332 (11)	−0.0001 (9)	0.0097 (8)	0.0019 (9)
C6	0.0316 (9)	0.0288 (11)	0.0274 (10)	0.0026 (8)	0.0068 (7)	0.0004 (8)
C7	0.0355 (9)	0.0323 (12)	0.0328 (11)	−0.0013 (8)	0.0053 (8)	−0.0034 (9)
Cl2	0.0540 (3)	0.0475 (3)	0.0305 (3)	0.0080 (3)	0.0091 (2)	−0.0060 (3)
O3	0.0750 (12)	0.0388 (11)	0.0384 (9)	0.0208 (10)	0.0121 (8)	0.0072 (9)
O4	0.0890 (14)	0.0535 (12)	0.0324 (9)	0.0303 (11)	0.0163 (9)	0.0112 (9)
N2	0.0545 (11)	0.0603 (17)	0.0320 (10)	0.0120 (11)	0.0095 (9)	0.0132 (11)
C8	0.0304 (8)	0.0325 (11)	0.0253 (9)	−0.0041 (8)	0.0073 (7)	−0.0026 (9)
C9	0.0319 (8)	0.0304 (10)	0.0335 (9)	0.0030 (9)	0.0072 (7)	0.0026 (10)
C10	0.0322 (9)	0.0419 (13)	0.0298 (10)	−0.0042 (9)	0.0062 (8)	0.0083 (9)
C11	0.0419 (10)	0.0379 (13)	0.0266 (10)	−0.0022 (9)	0.0077 (9)	−0.0037 (9)
C12	0.0421 (10)	0.0308 (11)	0.0314 (10)	−0.0001 (9)	0.0094 (8)	−0.0029 (9)
C13	0.0310 (9)	0.0290 (11)	0.0278 (10)	−0.0019 (8)	0.0057 (8)	0.0033 (8)
C14	0.0391 (10)	0.0322 (12)	0.0291 (10)	0.0004 (9)	0.0078 (8)	0.0039 (9)

Cl1—C1	1.732 (2)	C3—C4	1.390 (3)
Cl2—C8	1.735 (2)	C4—C5	1.375 (3)
O1—C7	1.302 (3)	C5—C6	1.401 (3)
O2—C7	1.226 (3)	C6—C7	1.475 (3)
O1—HO1	0.82 (3)	C2—H2	0.9300
O3—C14	1.299 (3)	C4—H4	0.9300
O4—C14	1.233 (3)	C5—H5	0.9300
O3—HO3	0.81 (3)	C8—C9	1.377 (3)
N1—C3	1.386 (3)	C8—C13	1.395 (3)
N1—HN1	0.85 (3)	C9—C10	1.391 (3)
N1—HN2	0.86 (3)	C10—C11	1.396 (4)
N2—C10	1.377 (3)	C11—C12	1.374 (3)
N2—HN4	0.86 (3)	C12—C13	1.400 (3)
N2—HN3	0.86 (3)	C13—C14	1.478 (3)
C1—C6	1.398 (3)	C9—H9	0.9300
C1—C2	1.383 (3)	C11—H11	0.9300
C2—C3	1.392 (3)	C12—H12	0.9300
C7—O1—HO1	108 (2)	C5—C4—H4	120.00
C14—O3—HO3	116 (2)	C3—C4—H4	120.00
C3—N1—HN1	111.7 (19)	C4—C5—H5	119.00
HN1—N1—HN2	112 (3)	C6—C5—H5	119.00
C3—N1—HN2	117 (2)	C9—C8—C13	121.7 (2)
C10—N2—HN4	115 (2)	Cl2—C8—C9	115.01 (18)
HN3—N2—HN4	117 (3)	Cl2—C8—C13	123.30 (18)
C10—N2—HN3	114.0 (19)	C8—C9—C10	120.7 (2)
Cl1—C1—C2	115.19 (18)	N2—C10—C11	121.2 (2)
Cl1—C1—C6	123.03 (18)	C9—C10—C11	118.7 (2)
C2—C1—C6	121.8 (2)	N2—C10—C9	120.0 (2)
C1—C2—C3	120.3 (2)	C10—C11—C12	119.7 (2)
C2—C3—C4	119.0 (2)	C11—C12—C13	122.6 (2)
N1—C3—C4	120.8 (2)	C8—C13—C12	116.5 (2)
N1—C3—C2	120.2 (2)	C8—C13—C14	124.8 (2)
C3—C4—C5	120.0 (2)	C12—C13—C14	118.7 (2)
C4—C5—C6	122.5 (2)	O3—C14—C13	114.2 (2)
C5—C6—C7	118.9 (2)	O4—C14—C13	123.5 (2)
C1—C6—C7	124.5 (2)	O3—C14—O4	122.3 (2)
C1—C6—C5	116.5 (2)	C8—C9—H9	120.00
O2—C7—C6	123.8 (2)	C10—C9—H9	120.00
O1—C7—C6	114.0 (2)	C10—C11—H11	120.00
O1—C7—O2	122.1 (2)	C12—C11—H11	120.00
C1—C2—H2	120.00	C11—C12—H12	119.00
C3—C2—H2	120.00	C13—C12—H12	119.00
Cl1—C1—C2—C3	−179.44 (17)	Cl2—C8—C9—C10	179.22 (17)
C6—C1—C2—C3	1.1 (3)	C13—C8—C9—C10	−0.9 (3)
Cl1—C1—C6—C5	−179.00 (17)	Cl2—C8—C13—C12	178.57 (17)
Cl1—C1—C6—C7	4.2 (3)	Cl2—C8—C13—C14	−3.3 (3)
C2—C1—C6—C5	0.4 (3)	C9—C8—C13—C12	−1.3 (3)
C2—C1—C6—C7	−176.4 (2)	C9—C8—C13—C14	176.8 (2)
C1—C2—C3—N1	−180.0 (2)	C8—C9—C10—N2	179.8 (2)
C1—C2—C3—C4	−2.5 (3)	C8—C9—C10—C11	2.6 (3)
N1—C3—C4—C5	179.9 (2)	N2—C10—C11—C12	−179.2 (2)
C2—C3—C4—C5	2.5 (3)	C9—C10—C11—C12	−2.0 (3)
C3—C4—C5—C6	−1.0 (4)	C10—C11—C12—C13	−0.2 (4)
C4—C5—C6—C1	−0.5 (3)	C11—C12—C13—C8	1.9 (3)
C4—C5—C6—C7	176.5 (2)	C11—C12—C13—C14	−176.4 (2)
C1—C6—C7—O1	−175.4 (2)	C8—C13—C14—O3	175.1 (2)
C1—C6—C7—O2	4.4 (4)	C8—C13—C14—O4	−5.7 (4)
C5—C6—C7—O1	7.8 (3)	C12—C13—C14—O3	−6.8 (3)
C5—C6—C7—O2	−172.3 (2)	C12—C13—C14—O4	172.4 (2)

D—H···A	D—H	H···A	D···A	D—H···A
O1—HO1···O4i	0.82 (3)	1.84 (3)	2.650 (3)	171 (3)
N1—HN2···N2	0.86 (3)	2.60 (3)	3.375 (4)	150 (3)
O3—HO3···O2ii	0.81 (3)	1.84 (3)	2.650 (3)	173 (3)
N2—HN3···Cl2iii	0.86 (3)	2.81 (3)	3.374 (2)	125 (2)
N2—HN4···N1iv	0.86 (3)	2.47 (3)	3.302 (4)	163 (2)

Table 1

Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—HO1⋯O4i	0.82 (3)	1.84 (3)	2.650 (3)	171 (3)
N1—HN2⋯N2	0.86 (3)	2.60 (3)	3.375 (4)	150 (3)
O3—HO3⋯O2ii	0.81 (3)	1.84 (3)	2.650 (3)	173 (3)
N2—HN3⋯Cl2iii	0.86 (3)	2.81 (3)	3.374 (2)	125 (2)
N2—HN4⋯N1iv	0.86 (3)	2.47 (3)	3.302 (4)	163 (2)

Symmetry codes: (i) ; (ii) ; (iii) ; (iv) .