organic compounds
3-Methyl-1,4-dioxo-1,4-dihydronaphthalen-2-yl 4-aminobenzoate
aDipartimento di Scienze Farmaceutiche Universitá di Firenze Via U. Schiff 6, I-50019 Sesto Fiorentino Firenze, Italy, and bDipartimento di Chimica Universitá di Firenze Via della Lastruccia 3, I-50019 Sesto Fiorentino Firenze, Italy
*Correspondence e-mail: massimo.divaira@unifi.it
The 18H13NO4, the oxidized form of the drug aminaftone used in venous disease therapy, is characterized by the presence of ribbons of hydrogen-bonded molecules parallel to the [111] crystallographic direction and by stacking interactions between rings [centroid–centroid distance between quinone rings = 3.684 (3) Å and between aminobenzoate rings = 4.157 (3) Å] along the ribbons.
of the title compound, CExperimental
Crystal data
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Refinement
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Data collection: CrysAlisPro CCD (Oxford Diffraction, 2006); cell CrysAlisPro CCD; data reduction: CrysAlisPro RED (Oxford Diffraction, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 and PARST (Nardelli, 1995).
Supporting information
10.1107/S1600536808005308/rk2078sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536808005308/rk2078Isup2.hkl
Samples of aminonaftone were kindly provided by SIMS (SIMS srl, Reggello Firenze, Italy). Crystals of I, suitable for X–ray
were obtained by slow evaporation from methanol solutions of aminaftone.Crystals did not diffract strongly and it was deemed that collecting data at θ higher than 72° would not yield improvement. Hydrogen atoms were in geometrically generated positions, riding, except for the amino H atoms, which were refined freely. The constraint U(H) = 1.2Ueq(C,N), or 1.5Ueq(C) for methyl group H atoms, was applied. Range of bond distances involving refined hydrogen atoms: N—H 0.89–0.95 Å.
Data collection: CrysAlis PRO CCD (Oxford Diffraction, 2006); cell
CrysAlis PRO CCD (Oxford Diffraction, 2006); data reduction: CrysAlis PRO RED (Oxford Diffraction, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PARST (Nardelli, 1995).C18H13NO4 | Z = 2 |
Mr = 307.29 | F(000) = 320 |
Triclinic, P1 | Dx = 1.431 Mg m−3 |
Hall symbol: -P 1 | Cu Kα radiation, λ = 1.54180 Å |
a = 7.6217 (6) Å | Cell parameters from 3411 reflections |
b = 9.6142 (7) Å | θ = 9.6–53.4° |
c = 10.6456 (7) Å | µ = 0.85 mm−1 |
α = 101.618 (6)° | T = 170 K |
β = 110.770 (7)° | Flat prism, red |
γ = 89.019 (6)° | 0.60 × 0.20 × 0.05 mm |
V = 713.18 (10) Å3 |
Oxford Diffraction Xcalibur PX Ultra CCD diffractometer | 2453 independent reflections |
Radiation source: Fine–focus sealed tube | 1845 reflections with I > 2σ(I) |
Oxford Diffraction Enhance ULTRA assembly monochromator | Rint = 0.022 |
Detector resolution: 8.1241 pixels mm-1 | θmax = 72.4°, θmin = 4.5° |
ω scans | h = −9→9 |
Absorption correction: multi-scan (ABSPACK; Oxford Diffraction, 2006) | k = −11→11 |
Tmin = 0.501, Tmax = 1.000 | l = −12→12 |
6339 measured reflections |
Refinement on F2 | Primary atom site location: Direct |
Least-squares matrix: Full | Secondary atom site location: Difmap |
R[F2 > 2σ(F2)] = 0.041 | Hydrogen site location: Difmap |
wR(F2) = 0.142 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.12 | w = 1/[σ2(Fo2) + (0.0941P)2 + 0.0064P] where P = (Fo2 + 2Fc2)/3 |
2453 reflections | (Δ/σ)max < 0.001 |
215 parameters | Δρmax = 0.17 e Å−3 |
0 restraints | Δρmin = −0.23 e Å−3 |
C18H13NO4 | γ = 89.019 (6)° |
Mr = 307.29 | V = 713.18 (10) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.6217 (6) Å | Cu Kα radiation |
b = 9.6142 (7) Å | µ = 0.85 mm−1 |
c = 10.6456 (7) Å | T = 170 K |
α = 101.618 (6)° | 0.60 × 0.20 × 0.05 mm |
β = 110.770 (7)° |
Oxford Diffraction Xcalibur PX Ultra CCD diffractometer | 2453 independent reflections |
Absorption correction: multi-scan (ABSPACK; Oxford Diffraction, 2006) | 1845 reflections with I > 2σ(I) |
Tmin = 0.501, Tmax = 1.000 | Rint = 0.022 |
6339 measured reflections |
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.142 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.12 | Δρmax = 0.17 e Å−3 |
2453 reflections | Δρmin = −0.23 e Å−3 |
215 parameters |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.6680 (2) | 1.03157 (16) | 0.34314 (16) | 0.0361 (4) | |
C2 | 0.8411 (2) | 1.01124 (16) | 0.32984 (16) | 0.0373 (4) | |
H2 | 0.8613 | 0.9234 | 0.2787 | 0.045* | |
C3 | 0.9857 (3) | 1.11583 (17) | 0.38923 (16) | 0.0392 (4) | |
H3 | 1.1038 | 1.0996 | 0.3791 | 0.047* | |
C4 | 0.9568 (3) | 1.24645 (17) | 0.46471 (16) | 0.0398 (4) | |
N | 1.0987 (3) | 1.35138 (17) | 0.52199 (17) | 0.0508 (4) | |
H1N | 1.083 (3) | 1.425 (3) | 0.582 (2) | 0.061* | |
H2N | 1.225 (4) | 1.326 (2) | 0.542 (2) | 0.061* | |
C5 | 0.7833 (3) | 1.26644 (17) | 0.47801 (17) | 0.0449 (5) | |
H5 | 0.7624 | 1.3542 | 0.5289 | 0.054* | |
C6 | 0.6405 (3) | 1.16127 (18) | 0.41876 (17) | 0.0431 (4) | |
H6 | 0.5226 | 1.1770 | 0.4294 | 0.052* | |
C7 | 0.5122 (3) | 0.92331 (17) | 0.27898 (16) | 0.0384 (4) | |
O1 | 0.57285 (17) | 0.79775 (12) | 0.22176 (13) | 0.0464 (4) | |
O2 | 0.35157 (19) | 0.93363 (13) | 0.27039 (14) | 0.0498 (4) | |
C8 | 0.4401 (2) | 0.68767 (16) | 0.14533 (17) | 0.0377 (4) | |
C9 | 0.4125 (2) | 0.58405 (18) | 0.22396 (17) | 0.0386 (4) | |
O3 | 0.48719 (18) | 0.60587 (14) | 0.34797 (12) | 0.0497 (4) | |
C10 | 0.2922 (2) | 0.45428 (17) | 0.14241 (18) | 0.0388 (4) | |
C11 | 0.2663 (3) | 0.3494 (2) | 0.2090 (2) | 0.0498 (5) | |
H11 | 0.3227 | 0.3623 | 0.3060 | 0.060* | |
C12 | 0.1572 (3) | 0.2263 (2) | 0.1317 (2) | 0.0602 (6) | |
H12 | 0.1414 | 0.1536 | 0.1761 | 0.072* | |
C13 | 0.0713 (3) | 0.2085 (2) | −0.0091 (2) | 0.0552 (5) | |
H13 | −0.0036 | 0.1239 | −0.0607 | 0.066* | |
C14 | 0.0936 (3) | 0.31287 (18) | −0.0752 (2) | 0.0466 (5) | |
H14 | 0.0330 | 0.3008 | −0.1719 | 0.056* | |
C15 | 0.2056 (2) | 0.43605 (16) | 0.00057 (17) | 0.0376 (4) | |
O4 | 0.1557 (2) | 0.53290 (14) | −0.19534 (13) | 0.0593 (4) | |
C16 | 0.2311 (2) | 0.54714 (17) | −0.07165 (17) | 0.0405 (4) | |
C17 | 0.3535 (2) | 0.67684 (17) | 0.01047 (18) | 0.0393 (4) | |
C18 | 0.3757 (3) | 0.7879 (2) | −0.0642 (2) | 0.0516 (5) | |
H181 | 0.4980 | 0.8401 | −0.0144 | 0.077* | |
H182 | 0.2753 | 0.8541 | −0.0699 | 0.077* | |
H183 | 0.3683 | 0.7421 | −0.1570 | 0.077* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0393 (10) | 0.0345 (8) | 0.0337 (8) | 0.0027 (8) | 0.0114 (7) | 0.0083 (6) |
C2 | 0.0443 (10) | 0.0325 (7) | 0.0329 (8) | 0.0035 (8) | 0.0118 (7) | 0.0059 (6) |
C3 | 0.0385 (10) | 0.0398 (8) | 0.0357 (8) | 0.0033 (8) | 0.0088 (7) | 0.0085 (7) |
C4 | 0.0435 (11) | 0.0382 (8) | 0.0318 (8) | −0.0001 (8) | 0.0065 (7) | 0.0066 (6) |
N | 0.0484 (10) | 0.0413 (8) | 0.0487 (9) | −0.0045 (8) | 0.0063 (7) | −0.0016 (7) |
C5 | 0.0529 (12) | 0.0360 (8) | 0.0417 (10) | 0.0019 (9) | 0.0175 (8) | −0.0017 (7) |
C6 | 0.0449 (11) | 0.0407 (9) | 0.0436 (9) | 0.0035 (8) | 0.0176 (8) | 0.0053 (7) |
C7 | 0.0443 (11) | 0.0347 (8) | 0.0362 (8) | 0.0032 (8) | 0.0136 (7) | 0.0091 (6) |
O1 | 0.0370 (7) | 0.0339 (6) | 0.0615 (8) | −0.0006 (5) | 0.0156 (6) | −0.0013 (5) |
O2 | 0.0410 (8) | 0.0444 (7) | 0.0622 (8) | 0.0016 (6) | 0.0202 (6) | 0.0040 (6) |
C8 | 0.0326 (9) | 0.0313 (7) | 0.0480 (10) | 0.0026 (7) | 0.0164 (7) | 0.0021 (7) |
C9 | 0.0322 (9) | 0.0423 (8) | 0.0402 (9) | 0.0065 (8) | 0.0137 (7) | 0.0050 (7) |
O3 | 0.0438 (8) | 0.0612 (8) | 0.0397 (7) | 0.0022 (6) | 0.0124 (5) | 0.0057 (6) |
C10 | 0.0331 (9) | 0.0366 (8) | 0.0476 (10) | 0.0031 (8) | 0.0153 (7) | 0.0092 (7) |
C11 | 0.0484 (12) | 0.0500 (10) | 0.0583 (11) | 0.0063 (9) | 0.0248 (9) | 0.0173 (9) |
C12 | 0.0629 (14) | 0.0438 (10) | 0.0877 (16) | −0.0002 (10) | 0.0405 (12) | 0.0192 (10) |
C13 | 0.0464 (12) | 0.0389 (9) | 0.0817 (15) | −0.0021 (9) | 0.0316 (10) | −0.0003 (9) |
C14 | 0.0366 (10) | 0.0391 (9) | 0.0578 (11) | 0.0037 (8) | 0.0157 (8) | −0.0017 (8) |
C15 | 0.0320 (9) | 0.0330 (8) | 0.0472 (10) | 0.0068 (7) | 0.0168 (7) | 0.0032 (7) |
O4 | 0.0774 (11) | 0.0530 (7) | 0.0385 (7) | 0.0067 (7) | 0.0124 (6) | 0.0053 (6) |
C16 | 0.0386 (10) | 0.0385 (8) | 0.0414 (10) | 0.0089 (8) | 0.0121 (7) | 0.0064 (7) |
C17 | 0.0368 (10) | 0.0355 (8) | 0.0477 (10) | 0.0073 (8) | 0.0173 (8) | 0.0095 (7) |
C18 | 0.0535 (12) | 0.0465 (10) | 0.0626 (12) | 0.0078 (9) | 0.0245 (9) | 0.0222 (9) |
C1—C2 | 1.383 (3) | C9—O3 | 1.213 (2) |
C1—C6 | 1.398 (2) | C9—C10 | 1.480 (2) |
C1—C7 | 1.463 (2) | C10—C15 | 1.392 (2) |
C2—C3 | 1.383 (2) | C10—C11 | 1.397 (2) |
C2—H2 | 0.9500 | C11—C12 | 1.387 (3) |
C3—C4 | 1.407 (2) | C11—H11 | 0.9500 |
C3—H3 | 0.9500 | C12—C13 | 1.382 (3) |
C4—N | 1.371 (2) | C12—H12 | 0.9500 |
C4—C5 | 1.385 (3) | C13—C14 | 1.381 (3) |
N—H1N | 0.89 (2) | C13—H13 | 0.9500 |
N—H2N | 0.95 (3) | C14—C15 | 1.394 (2) |
C5—C6 | 1.378 (2) | C14—H14 | 0.9500 |
C5—H5 | 0.9500 | C15—C16 | 1.488 (2) |
C6—H6 | 0.9500 | O4—C16 | 1.215 (2) |
C7—O2 | 1.199 (2) | C16—C17 | 1.487 (2) |
C7—O1 | 1.388 (2) | C17—C18 | 1.498 (2) |
O1—C8 | 1.3827 (19) | C18—H181 | 0.9800 |
C8—C17 | 1.333 (2) | C18—H182 | 0.9800 |
C8—C9 | 1.485 (2) | C18—H183 | 0.9800 |
C2—C1—C6 | 118.63 (15) | C15—C10—C11 | 120.01 (16) |
C2—C1—C7 | 122.37 (15) | C15—C10—C9 | 120.57 (14) |
C6—C1—C7 | 118.99 (16) | C11—C10—C9 | 119.42 (16) |
C1—C2—C3 | 121.52 (15) | C12—C11—C10 | 119.25 (19) |
C1—C2—H2 | 119.2 | C12—C11—H11 | 120.4 |
C3—C2—H2 | 119.2 | C10—C11—H11 | 120.4 |
C2—C3—C4 | 119.58 (17) | C13—C12—C11 | 120.62 (17) |
C2—C3—H3 | 120.2 | C13—C12—H12 | 119.7 |
C4—C3—H3 | 120.2 | C11—C12—H12 | 119.7 |
N—C4—C5 | 121.40 (16) | C14—C13—C12 | 120.40 (17) |
N—C4—C3 | 119.83 (18) | C14—C13—H13 | 119.8 |
C5—C4—C3 | 118.76 (15) | C12—C13—H13 | 119.8 |
C4—N—H1N | 116.7 (15) | C13—C14—C15 | 119.68 (18) |
C4—N—H2N | 119.0 (13) | C13—C14—H14 | 120.2 |
H1N—N—H2N | 114 (2) | C15—C14—H14 | 120.2 |
C6—C5—C4 | 121.14 (16) | C10—C15—C14 | 120.02 (16) |
C6—C5—H5 | 119.4 | C10—C15—C16 | 120.62 (14) |
C4—C5—H5 | 119.4 | C14—C15—C16 | 119.37 (16) |
C5—C6—C1 | 120.36 (17) | O4—C16—C17 | 120.01 (15) |
C5—C6—H6 | 119.8 | O4—C16—C15 | 121.32 (15) |
C1—C6—H6 | 119.8 | C17—C16—C15 | 118.67 (14) |
O2—C7—O1 | 121.27 (15) | C8—C17—C16 | 118.88 (14) |
O2—C7—C1 | 128.52 (16) | C8—C17—C18 | 123.35 (16) |
O1—C7—C1 | 110.20 (15) | C16—C17—C18 | 117.75 (15) |
C8—O1—C7 | 118.14 (13) | C17—C18—H181 | 109.5 |
C17—C8—O1 | 120.33 (14) | C17—C18—H182 | 109.5 |
C17—C8—C9 | 124.77 (14) | H181—C18—H182 | 109.5 |
O1—C8—C9 | 114.83 (14) | C17—C18—H183 | 109.5 |
O3—C9—C10 | 122.82 (15) | H181—C18—H183 | 109.5 |
O3—C9—C8 | 120.89 (15) | H182—C18—H183 | 109.5 |
C10—C9—C8 | 116.28 (14) | ||
C6—C1—C2—C3 | −0.1 (2) | C8—C9—C10—C11 | 177.37 (17) |
C7—C1—C2—C3 | 178.82 (14) | C15—C10—C11—C12 | 1.4 (3) |
C1—C2—C3—C4 | −0.2 (2) | C9—C10—C11—C12 | −178.40 (17) |
C2—C3—C4—N | −178.97 (15) | C10—C11—C12—C13 | −1.5 (3) |
C2—C3—C4—C5 | 0.3 (2) | C11—C12—C13—C14 | 0.3 (3) |
N—C4—C5—C6 | 179.17 (15) | C12—C13—C14—C15 | 0.8 (3) |
C3—C4—C5—C6 | −0.1 (3) | C11—C10—C15—C14 | −0.3 (3) |
C4—C5—C6—C1 | −0.2 (3) | C9—C10—C15—C14 | 179.56 (16) |
C2—C1—C6—C5 | 0.3 (2) | C11—C10—C15—C16 | 179.70 (16) |
C7—C1—C6—C5 | −178.65 (15) | C9—C10—C15—C16 | −0.5 (3) |
C2—C1—C7—O2 | −171.14 (16) | C13—C14—C15—C10 | −0.9 (3) |
C6—C1—C7—O2 | 7.8 (3) | C13—C14—C15—C16 | 179.15 (17) |
C2—C1—C7—O1 | 7.5 (2) | C10—C15—C16—O4 | −179.69 (17) |
C6—C1—C7—O1 | −173.56 (14) | C14—C15—C16—O4 | 0.3 (3) |
O2—C7—O1—C8 | 4.8 (2) | C10—C15—C16—C17 | 1.0 (3) |
C1—C7—O1—C8 | −174.01 (13) | C14—C15—C16—C17 | −179.01 (16) |
C7—O1—C8—C17 | 89.9 (2) | O1—C8—C17—C16 | 171.84 (14) |
C7—O1—C8—C9 | −92.86 (17) | C9—C8—C17—C16 | −5.1 (3) |
C17—C8—C9—O3 | −175.24 (17) | O1—C8—C17—C18 | −7.0 (3) |
O1—C8—C9—O3 | 7.7 (2) | C9—C8—C17—C18 | 176.11 (16) |
C17—C8—C9—C10 | 5.5 (3) | O4—C16—C17—C8 | −177.60 (17) |
O1—C8—C9—C10 | −171.56 (14) | C15—C16—C17—C8 | 1.7 (2) |
O3—C9—C10—C15 | 178.30 (17) | O4—C16—C17—C18 | 1.3 (3) |
C8—C9—C10—C15 | −2.5 (2) | C15—C16—C17—C18 | −179.42 (16) |
O3—C9—C10—C11 | −1.9 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
N—H2N···O3i | 0.95 (3) | 2.13 (3) | 2.960 (2) | 145.6 (19) |
N—H1N···O4ii | 0.89 (2) | 2.25 (2) | 3.045 (2) | 147.3 (19) |
Symmetry codes: (i) −x+2, −y+2, −z+1; (ii) x+1, y+1, z+1. |
Experimental details
Crystal data | |
Chemical formula | C18H13NO4 |
Mr | 307.29 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 170 |
a, b, c (Å) | 7.6217 (6), 9.6142 (7), 10.6456 (7) |
α, β, γ (°) | 101.618 (6), 110.770 (7), 89.019 (6) |
V (Å3) | 713.18 (10) |
Z | 2 |
Radiation type | Cu Kα |
µ (mm−1) | 0.85 |
Crystal size (mm) | 0.60 × 0.20 × 0.05 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur PX Ultra CCD diffractometer |
Absorption correction | Multi-scan (ABSPACK; Oxford Diffraction, 2006) |
Tmin, Tmax | 0.501, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6339, 2453, 1845 |
Rint | 0.022 |
(sin θ/λ)max (Å−1) | 0.618 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.142, 1.12 |
No. of reflections | 2453 |
No. of parameters | 215 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.17, −0.23 |
Computer programs: CrysAlis PRO CCD (Oxford Diffraction, 2006), CrysAlis PRO RED (Oxford Diffraction, 2006), SIR97 (Altomare et al., 1999), ORTEP-3 (Farrugia, 1997) and PLATON (Spek, 2003), SHELXL97 (Sheldrick, 2008) and PARST (Nardelli, 1995).
D—H···A | D—H | H···A | D···A | D—H···A |
N—H2N···O3i | 0.95 (3) | 2.13 (3) | 2.960 (2) | 145.6 (19) |
N—H1N···O4ii | 0.89 (2) | 2.25 (2) | 3.045 (2) | 147.3 (19) |
Symmetry codes: (i) −x+2, −y+2, −z+1; (ii) x+1, y+1, z+1. |
Acknowledgements
The authors acknowledge financial support from the Italian Ministero dell'Istruzione, dell'Universitá e della Ricerca.
References
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Previuos studies concerning the quality control of aminaftone, 4–aminobenzoic acid 1,4–dihydroxy–3–methyl–naphtalen–2–yl ester, which is the active pharmaceutical ingredient of some commercial drugs used in the therapy of chronic venous and lymphatic stasis (De Anna et al., 1989; Martinez et al., 2005), have shown that this drug substance rapidly undergoes oxidation in solution at room temperature. The oxidized compound, featuring a quinone ring instead of a hydroquinone moiety, is also a potential impurity of the bulk drug. A structure determination of the oxidized form, I, has been undertaken at 170 K.
There are two molecules of I, related by the inversion centre, in the triclinic unit cell. The molecular geometry and labelling are shown in Fig 1. Bond distances are consistent with the presence of the quinonic form. Each molecule behaves as a hydrogen–bond donor, toward two other molecules, through its aminic H atoms: N—H2N···O3i (N···O3i = 2.960 (2) Å, N—H2N···O3i = 146 (2)°; symmetry code (i): 2 - x, 2 - y, 1 - z) and N—H1N···O4ii (N···O4ii = 3.045 (2) Å, N—H1N···O4ii = 147 (2)°; symmetry code (ii): 1 + x, 1 + y, 1 + z). Conversely, through the above hydrogen bonds each molecule behaves as an acceptor from two separate molecules, by means of its quinone O atoms. As a result, ribbons of hydrogen–bonded molecules, parallel to the crystallographic [1 1 1] direction, are formed (Fig. 2). Moreover, stacking interactions occur along the ribbons, with 3.684 (3)Å distance between the centroids of symmetry–related quinone rings and 4.157 (3)Å distance between the centroids of the aminobenzoic rings, the shortest C···C contact distances between atoms of facing rings being C8···C16iii = 3.532 (3)Å ((iii): 1 - x, 1 - y, -z) and C2···C3i = 3.286 (2) Å, respectively, for the above two types of interactions. The largest deviation (0.098 (1) Å) from the plane of the aminobenzoic group is presented by the carbonylic O2 atom whereas, among the atoms lying on the naphtoquinone plane, the hinge atom O1 exhibits the largest deviation (0.141 (2) Å) from that plane; the angle between these two planes measures 84.46 (3)°.