3,4-Methyl­enedioxy­benzoic acid

The crystal structure of the title compound, C₈H₆O₄, consists of layers of characteristic dimers formed by inter­molecular O—H...O hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 298 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.043
• wR factor = 0.134
• Data-to-parameter ratio = 14.8

checkCIF/PLATON results

No syntax errors found



Alert level B
CELLV02_ALERT_1_B  The supplied cell volume s.u. differs from that
            calculated from the cell parameter s.u.'s by > 4
            Calculated cell volume su =      17.23
            Cell volume su given      =      12.00

Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT152_ALERT_1_C Supplied and Calc Volume s.u. Inconsistent .....          ?
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.16

   0 ALERT level A = In general: serious problem
   1 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   3 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: RAPID-AUTO (Rigaku, 2004); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL/NT.

(I)

Crystal data

C8H6O4	F(000) = 172
Mr = 166.13	Dx = 1.555 Mg m^−3
Triclinic, P1	Melting point: 502 K
a = 7.0685 (14) Å	Mo Kα radiation, λ = 0.71073 Å
b = 7.1553 (14) Å	Cell parameters from 2904 reflections
c = 8.1436 (16) Å	θ = 3.2–27.5°
α = 90.39 (3)°	µ = 0.13 mm^−1
β = 107.51 (3)°	T = 298 K
γ = 114.06 (3)°	Column, colorless
V = 354.67 (12) Å^3	0.37 × 0.26 × 0.15 mm
Z = 2

Data collection

Rigaku r-axis rapid IP area detector diffractometer	1613 independent reflections
Radiation source: rotating anode	1158 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.027
ω? φ? scans	θmax = 27.5°, θmin = 3.2°
Absorption correction: multi-scan SADABS	h = −9→9
Tmin = 0.954, Tmax = 0.981	k = −8→9
3553 measured reflections	l = −10→10

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.043	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.134	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.085P)^2] where P = (Fo^2 + 2Fc^2)/3
1613 reflections	(Δ/σ)max < 0.001
109 parameters	Δρmax = 0.23 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
O1	0.4020 (2)	0.06085 (19)	1.28801 (14)	0.0527 (4)
O2	0.3899 (2)	0.3753 (2)	1.32834 (13)	0.0603 (4)
O3	0.0949 (2)	0.55282 (19)	0.72403 (14)	0.0592 (4)
H3B	0.0540	0.5903	0.6302	0.089*
O4	0.0276 (2)	0.27784 (19)	0.54766 (13)	0.0532 (4)
C1	0.4323 (3)	0.2173 (3)	1.4156 (2)	0.0529 (4)
H1A	0.3325	0.1587	1.4807	0.063*
H1B	0.5816	0.2748	1.4966	0.063*
C2	0.3225 (2)	0.1155 (2)	1.13044 (19)	0.0364 (4)
C3	0.2581 (3)	0.0089 (2)	0.96815 (19)	0.0398 (4)
H3A	0.2640	−0.1173	0.9527	0.048*
C4	0.1835 (2)	0.0996 (2)	0.82812 (18)	0.0374 (4)
H4A	0.1383	0.0323	0.7157	0.045*
C5	0.1745 (2)	0.2874 (2)	0.85107 (17)	0.0340 (3)
C6	0.0941 (2)	0.3767 (2)	0.69805 (18)	0.0375 (4)
C7	0.2418 (2)	0.3946 (2)	1.01842 (18)	0.0382 (4)
H7A	0.2367	0.5209	1.0356	0.046*
C8	0.3150 (2)	0.3031 (2)	1.15476 (17)	0.0379 (4)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0733 (8)	0.0535 (7)	0.0370 (6)	0.0380 (6)	0.0105 (5)	0.0154 (5)
O2	0.1010 (10)	0.0549 (8)	0.0257 (5)	0.0453 (7)	0.0054 (6)	0.0051 (5)
O3	0.0983 (10)	0.0482 (7)	0.0334 (6)	0.0445 (7)	0.0064 (6)	0.0065 (5)
O4	0.0810 (9)	0.0490 (7)	0.0274 (5)	0.0330 (6)	0.0079 (5)	0.0044 (5)
C1	0.0727 (11)	0.0565 (10)	0.0337 (7)	0.0352 (9)	0.0127 (7)	0.0141 (7)
C2	0.0377 (8)	0.0384 (8)	0.0341 (7)	0.0183 (6)	0.0106 (6)	0.0112 (6)
C3	0.0477 (9)	0.0346 (7)	0.0400 (7)	0.0215 (7)	0.0133 (6)	0.0050 (6)
C4	0.0441 (8)	0.0348 (8)	0.0322 (6)	0.0170 (6)	0.0111 (6)	0.0015 (6)
C5	0.0378 (8)	0.0331 (7)	0.0283 (7)	0.0132 (6)	0.0100 (6)	0.0055 (6)
C6	0.0470 (8)	0.0352 (7)	0.0294 (7)	0.0187 (6)	0.0099 (6)	0.0045 (6)
C7	0.0513 (9)	0.0320 (7)	0.0301 (7)	0.0197 (7)	0.0092 (6)	0.0045 (6)
C8	0.0458 (8)	0.0371 (8)	0.0277 (6)	0.0176 (6)	0.0081 (6)	0.0041 (6)

Geometric parameters (Å, º)

O1—C2	1.366 (2)	C2—C8	1.380 (2)
O1—C1	1.426 (2)	C3—C4	1.388 (2)
O2—C8	1.365 (2)	C3—H3A	0.9300
O2—C1	1.426 (2)	C4—C5	1.385 (2)
O3—C6	1.274 (2)	C4—H4A	0.9300
O3—H3B	0.8200	C5—C7	1.404 (2)
O4—C6	1.262 (2)	C5—C6	1.472 (2)
C1—H1A	0.9700	C7—C8	1.367 (2)
C1—H1B	0.9700	C7—H7A	0.9300
C2—C3	1.370 (2)
C2—O1—C1	105.75 (13)	C5—C4—C3	121.90 (14)
C8—O2—C1	105.74 (14)	C5—C4—H4A	119.1
C6—O3—H3B	109.5	C3—C4—H4A	119.1
O2—C1—O1	108.28 (13)	C4—C5—C7	120.98 (13)
O2—C1—H1A	110.0	C4—C5—C6	119.67 (13)
O1—C1—H1A	110.0	C7—C5—C6	119.34 (14)
O2—C1—H1B	110.0	O4—C6—O3	122.62 (13)
O1—C1—H1B	110.0	O4—C6—C5	119.48 (14)
H1A—C1—H1B	108.4	O3—C6—C5	117.91 (13)
O1—C2—C3	127.86 (15)	C8—C7—C5	116.32 (15)
O1—C2—C8	109.86 (14)	C8—C7—H7A	121.8
C3—C2—C8	122.28 (13)	C5—C7—H7A	121.8
C2—C3—C4	116.29 (15)	O2—C8—C7	127.77 (15)
C2—C3—H3A	121.9	O2—C8—C2	110.00 (13)
C4—C3—H3A	121.9	C7—C8—C2	122.22 (14)
C8—O2—C1—O1	6.0 (2)	C7—C5—C6—O3	2.0 (2)
C2—O1—C1—O2	−5.88 (19)	C4—C5—C7—C8	−0.1 (2)
C1—O1—C2—C3	−176.77 (16)	C6—C5—C7—C8	−179.89 (14)
C1—O1—C2—C8	3.54 (18)	C1—O2—C8—C7	176.33 (17)
O1—C2—C3—C4	−179.87 (15)	C1—O2—C8—C2	−3.86 (19)
C8—C2—C3—C4	−0.2 (2)	C5—C7—C8—O2	179.64 (15)
C2—C3—C4—C5	0.0 (2)	C5—C7—C8—C2	−0.2 (2)
C3—C4—C5—C7	0.2 (2)	O1—C2—C8—O2	0.21 (19)
C3—C4—C5—C6	179.99 (14)	C3—C2—C8—O2	−179.51 (14)
C4—C5—C6—O4	2.2 (2)	O1—C2—C8—C7	−179.97 (15)
C7—C5—C6—O4	−177.97 (13)	C3—C2—C8—C7	0.3 (3)
C4—C5—C6—O3	−177.76 (14)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3B···O4^i	0.82	1.81	2.618 (2)	167

Symmetry code: (i) −x, −y+1, −z+1.