4-Amino­phenyl­acetic acid

Crystals of the title compound, C₈H₉NO₂, were obtained from ethyl acetate. The structure consists of the acid in its zwitterionic form. In the crystal structure, each mol­ecule interacts through strong N—H...O hydrogen bonds with six adjacent mol­ecules, yielding a three-dimensional network.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C)= 0.003 Å
• R factor = 0.059
• wR factor = 0.133
• Data-to-parameter ratio = 14.1

checkCIF/PLATON results

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Computing details

Data collection: COLLECT (Nonius, 1999); cell refinement: DIRAX/LSQ (Duisenberg, 1992); data reduction: EVALCCD (Duisenberg et al., 2003); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997).

4-aminophenylacetic acid

Crystal data

C8H9NO2	F(000) = 640
Mr = 151.17	Dx = 1.369 Mg m^−3
Orthorhombic, Pbca	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2ab	Cell parameters from 72 reflections
a = 11.3184 (10) Å	θ = 5.1–20.5°
b = 7.6823 (7) Å	µ = 0.10 mm^−1
c = 16.8656 (12) Å	T = 298 K
V = 1466.5 (2) Å^3	Fragment, colourless
Z = 8	0.39 × 0.32 × 0.21 mm

Data collection

Bruker–Nonius KappaCCD diffractometer	Rint = 0.074
Radiation source: fine-focus sealed tube	θmax = 26.0°, θmin = 4.6°
φ and ω scans	h = −13→13
11376 measured reflections	k = −9→9
1425 independent reflections	l = −19→20
1027 reflections with I > 2σ(I)

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	H-atom parameters constrained
R[F^2 > 2σ(F^2)] = 0.059	w = 1/[σ^2(Fo^2) + (0.0313P)^2 + 1.286P] where P = (Fo^2 + 2Fc^2)/3
wR(F^2) = 0.133	(Δ/σ)max = 0.001
S = 1.16	Δρmax = 0.20 e Å^−3
1425 reflections	Δρmin = −0.18 e Å^−3
101 parameters	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
0 restraints	Extinction coefficient: 0.0093 (16)
Primary atom site location: structure-invariant direct methods

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	0.86904 (18)	0.0261 (3)	0.60027 (10)	0.0362 (5)
O2	0.82987 (17)	−0.1966 (2)	1.04684 (9)	0.0452 (5)
C2	0.9582 (2)	0.0814 (3)	0.73027 (13)	0.0384 (6)
O1	0.9374 (2)	−0.2822 (3)	0.94603 (11)	0.0632 (7)
C1	0.8666 (2)	0.0152 (3)	0.68639 (13)	0.0315 (5)
C6	0.7705 (2)	−0.0610 (3)	0.72175 (14)	0.0424 (6)
C3	0.9524 (2)	0.0711 (3)	0.81246 (14)	0.0414 (6)
C4	0.8561 (2)	−0.0025 (3)	0.84954 (13)	0.0383 (6)
C7	0.8732 (2)	−0.1751 (3)	0.97865 (14)	0.0380 (6)
C5	0.7660 (2)	−0.0681 (4)	0.80361 (15)	0.0455 (7)
C8	0.8450 (3)	−0.0040 (3)	0.93810 (14)	0.0489 (7)
H1A	0.9380	0.0781	0.5842	0.043*
H1B	0.8583	−0.0858	0.5795	0.043*
H1C	0.7994	0.0864	0.5812	0.043*
H2	1.0362	0.1273	0.7013	0.046*
H6	0.6969	−0.1055	0.6877	0.051*
H3	1.0273	0.1185	0.8440	0.050*
H5	0.6958	−0.1214	0.8310	0.055*
H8A	0.8984	0.0903	0.9643	0.059*
H8B	0.7669	0.0234	0.9523	0.059*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0405 (11)	0.0377 (11)	0.0303 (10)	−0.0033 (9)	−0.0019 (8)	−0.0007 (8)
O2	0.0597 (11)	0.0461 (11)	0.0297 (9)	0.0050 (9)	0.0062 (8)	0.0046 (8)
C2	0.0372 (13)	0.0446 (14)	0.0334 (13)	−0.0013 (11)	0.0014 (10)	0.0008 (11)
O1	0.0755 (14)	0.0615 (13)	0.0527 (12)	0.0329 (12)	0.0158 (10)	0.0064 (10)
C1	0.0368 (12)	0.0302 (11)	0.0276 (11)	0.0009 (10)	0.0011 (9)	0.0007 (9)
C6	0.0435 (14)	0.0431 (15)	0.0406 (14)	−0.0094 (12)	−0.0019 (11)	0.0019 (11)
C3	0.0442 (14)	0.0444 (14)	0.0354 (13)	−0.0004 (12)	−0.0031 (11)	−0.0015 (11)
C4	0.0528 (15)	0.0311 (11)	0.0310 (12)	0.0055 (11)	0.0039 (11)	0.0030 (10)
C7	0.0441 (14)	0.0386 (13)	0.0315 (12)	0.0030 (12)	0.0001 (11)	0.0005 (10)
C5	0.0486 (15)	0.0460 (16)	0.0421 (14)	−0.0082 (13)	0.0107 (12)	0.0086 (12)
C8	0.0718 (19)	0.0414 (15)	0.0334 (14)	0.0111 (14)	0.0093 (12)	0.0039 (11)

Geometric parameters (Å, º)

N1—C1	1.455 (3)	C7—C8	1.516 (3)
O2—C7	1.261 (3)	N1—H1A	0.9182
C2—C1	1.372 (3)	N1—H1B	0.9363
C2—C3	1.390 (3)	N1—H1C	0.9690
O1—C7	1.227 (3)	C2—H2	1.0692
C1—C6	1.371 (3)	C6—H6	1.0684
C6—C5	1.383 (3)	C3—H3	1.0647
C3—C4	1.378 (3)	C5—H5	1.0062
C4—C5	1.376 (4)	C8—H8A	1.0418
C4—C8	1.499 (3)	C8—H8B	0.9397
C1—C2—C3	118.8 (2)	C1—N1—H1C	110.1
C6—C1—C2	121.5 (2)	H1A—N1—H1C	112.7
C6—C1—N1	118.3 (2)	H1B—N1—H1C	102.1
C2—C1—N1	120.2 (2)	C1—C2—H2	120.0
C1—C6—C5	118.7 (2)	C3—C2—H2	120.9
C4—C3—C2	120.9 (2)	C1—C6—H6	121.4
C5—C4—C3	118.7 (2)	C5—C6—H6	119.7
C5—C4—C8	119.7 (2)	C4—C3—H3	122.9
C3—C4—C8	121.4 (2)	C2—C3—H3	116.2
O1—C7—O2	123.5 (2)	C4—C5—H5	118.4
O1—C7—C8	120.2 (2)	C6—C5—H5	120.3
O2—C7—C8	116.3 (2)	C4—C8—H8A	111.6
C4—C5—C6	121.4 (2)	C7—C8—H8A	106.8
C4—C8—C7	116.0 (2)	C4—C8—H8B	109.3
C1—N1—H1A	109.6	C7—C8—H8B	106.1
C1—N1—H1B	108.6	H8A—C8—H8B	106.4
H1A—N1—H1B	113.5

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1^i	0.92	1.84	2.753 (3)	170
N1—H1B···O2^ii	0.94	1.79	2.723 (3)	175
N1—H1C···O2^iii	0.97	1.79	2.756 (3)	179

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