Dimethyl 2,2′-(p-phenyl­enedi­oxy)­diacetate

The title compound, C₁₂H₁₄O₆, was prepared by the Williamson reaction of 1,4-dihydroxy­benzene and methyl chloro­acetate with phase-transfer catalysis. The compound lies on an inversion center. The structure is stabilized by weak C—H...π inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.058
• wR factor = 0.173
• Data-to-parameter ratio = 13.7

checkCIF/PLATON results

No syntax errors found



Alert level C
            Value of measurement temperature given =   293.000
            Value of melting point given =     0.000
PLAT062_ALERT_4_C Rescale T(min) & T(max) by .....................       1.01

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

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

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 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
   0 ALERT type 5 Informative message, check

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S1. Comment

The derivatives of aryloxyacetic acids and their derivatives constitute a class of compounds for both biological activity and plant growth regulators (Nagy et al., 1997; Wei et al.,2005). The phase-transfer catalysis, with the advantages of simple experimental operations, mild reaction conditions, and inexpensive and environmentally benign reagents, has established its significance in organic synthesis as one of the most useful methods for the acceleration of heterogeneous reactions (Perreux & Loupy, 2001).

Benzothiazole are remarkable heterocyclic ring systems. They have been found to exhibit a wide spectrum of biological activities. Many kinds of 2-substituted benzothiazoles are utilized as vulcanization accelators in the manufacture of rubber,as fluorescent brightening agents in textile dyeing,and in the leather industry (Chakraborti et al.,2004; Seijas et al.,2007; Wang et al.,2009). There are numerous synthetic methods to produce 2-arylbenzothiazoles. The most important ones include the reaction of o-aminothiophenols with benzoic acids or their derivatives (Chakraborti et al.,2004; Seijas et al.,2007; Wang et al.,2009). We are focusing on the synthesis of new products of bisbenzothiazole. We here report the crystal structure of the title compound (I).

The compound (I) lies on an inversion center(Fig.1). All bond lengths are within normal ranges (Allen et al., 1987). There are no typical hydrogen bonds, while weak intermolecular C—H···π interactions involving benzene ring (C1/C3/C2/C1a/C3a/C2a) (Table 1) may help in stabilizing the structure.

Related literature

For details of the synthesis procedure and the applications of benzothiazoles, see: Chakraborti et al. (2004); Seijas et al. (2007); Wang et al. (2009). For details of the synthesis procedure and the applications of aryloxyacetic acids, see: Nagy et al. (1997); Wei et al. (2005). For the use of phase-transfer catalysis in organic synthesis, see: Perreux et al. (2001). For bond-length data, see: Allen et al. (1987).

S2. Experimental

5.5 g (0.05 mole) hydroquinone was dissolved in 50 ml acetone, 6.9 g (0.05 mole) potassium carbonate, potassium iodide 0.8 g and tetrabutyl ammonium bromide 1.0 g were added. Then 8.8 ml L (0.10 mole) of methyl chloroacetate was dropped into the mixture. The mixture was boiled for 5 h with intensive stirring, cooled to room temperature, and filtered. The organic solution was evaporated under vacuum to dryness and the dry residue was recrystallized from methanol to obtain title compound. Crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of ethyl acetate. ¹H NMR (CDCl₃, δ, p.p.m.) 6.85 (m, 4H), 4.58 (s, 4H), 3.79 (s,6H).

S3. Refinement

All H atoms were positioned geometrically and treated as riding on their parent C atoms with C—H = 0.93 Å (aromatic), 0.97Å (methylene) and 0.96Å (methyl) with U_iso(H) = xU_eq(C), where x= 1.5 for methyl H and 1.2 for aromatic and methylene H atoms.

Computing details

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

Fig. 1. A view of the molecular structure of (I) showing the atom-numbering scheme. Ellipsoids are drawn at the 30% probability level. H atoms are represented as small spheres of arbitrary radii. [symmetry code: (A) 1/2-x, 1/2+y, 1/2-z].

Dimethyl 2,2'-(p-phenylenedioxy)diacetate

Crystal data

C12H14O6	F(000) = 268
Mr = 254.23	Dx = 1.367 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 27 reflections
a = 7.4190 (15) Å	θ = 1–25°
b = 7.0990 (14) Å	µ = 0.11 mm^−1
c = 11.785 (2) Å	T = 293 K
β = 95.49 (3)°	Block, yellow
V = 617.8 (2) Å^3	0.30 × 0.20 × 0.10 mm
Z = 2

Data collection

Enraf–Nonius CAD-4 diffractometer	769 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.000
Graphite monochromator	θmax = 25.3°, θmin = 3.1°
ω/2θ scans	h = −8→8
Absorption correction: ψ scan (North et al., 1968)	k = 0→8
Tmin = 0.954, Tmax = 0.977	l = 0→14
1123 measured reflections	3 standard reflections every 200 reflections
1123 independent reflections	intensity decay: 9%

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)] = 0.058	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.173	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.1P)^2 + 0.23P] where P = (Fo^2 + 2Fc^2)/3
1123 reflections	(Δ/σ)max = 0.001
82 parameters	Δρmax = 0.26 e Å^−3
0 restraints	Δρmin = −0.24 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	1.1983 (3)	0.2968 (2)	−0.07350 (16)	0.0520 (6)
O2	1.3969 (3)	0.5931 (3)	−0.13385 (19)	0.0636 (7)
O3	1.6159 (2)	0.3997 (3)	−0.17937 (17)	0.0531 (6)
C1	0.8429 (3)	0.0447 (3)	0.0519 (2)	0.0431 (7)
H1A	0.7382	0.0734	0.0859	0.052*
C2	0.9507 (3)	0.1863 (4)	0.0139 (2)	0.0444 (7)
H2A	0.9186	0.3114	0.0235	0.053*
C3	1.1039 (3)	0.1452 (4)	−0.0376 (2)	0.0425 (7)
C4	1.3668 (3)	0.2569 (4)	−0.1199 (2)	0.0460 (7)
H4A	1.3449	0.1844	−0.1896	0.055*
H4B	1.4456	0.1845	−0.0658	0.055*
C5	1.4535 (3)	0.4417 (4)	−0.1439 (2)	0.0441 (7)
C6	1.7243 (4)	0.5536 (4)	−0.2101 (3)	0.0617 (8)
H6A	1.8350	0.5067	−0.2354	0.093*
H6B	1.7513	0.6340	−0.1452	0.093*
H6C	1.6595	0.6240	−0.2705	0.093*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0553 (11)	0.0450 (11)	0.0577 (12)	0.0023 (9)	0.0163 (9)	0.0020 (9)
O2	0.0667 (14)	0.0491 (12)	0.0760 (16)	0.0059 (10)	0.0130 (11)	−0.0036 (11)
O3	0.0517 (11)	0.0536 (12)	0.0555 (12)	−0.0040 (9)	0.0125 (9)	−0.0034 (9)
C1	0.0441 (14)	0.0464 (14)	0.0381 (14)	0.0046 (11)	−0.0002 (10)	−0.0050 (11)
C2	0.0433 (14)	0.0448 (14)	0.0444 (16)	0.0021 (11)	0.0006 (11)	−0.0049 (12)
C3	0.0451 (14)	0.0459 (14)	0.0356 (14)	0.0001 (11)	−0.0011 (11)	0.0007 (11)
C4	0.0395 (13)	0.0500 (15)	0.0473 (15)	−0.0007 (11)	−0.0018 (11)	0.0007 (12)
C5	0.0519 (15)	0.0476 (15)	0.0314 (13)	0.0028 (12)	−0.0031 (11)	−0.0023 (11)
C6	0.0703 (19)	0.0603 (18)	0.0553 (18)	−0.0192 (15)	0.0100 (14)	0.0034 (15)

Geometric parameters (Å, º)

O1—C3	1.372 (3)	C2—C3	1.370 (4)
O1—C4	1.440 (3)	C2—H2A	0.9300
O2—C5	1.164 (3)	C4—C5	1.499 (4)
O3—C5	1.347 (3)	C4—H4A	0.9700
O3—C6	1.424 (3)	C4—H4B	0.9700
C1—C2	1.385 (4)	C6—H6A	0.9600
C1—C3^i	1.419 (3)	C6—H6B	0.9600
C1—H1A	0.9300	C6—H6C	0.9600
C3—O1—C4	116.7 (2)	C5—C4—H4A	110.2
C5—O3—C6	116.9 (2)	O1—C4—H4B	110.2
C2—C1—C3^i	118.4 (2)	C5—C4—H4B	110.2
C2—C1—H1A	120.8	H4A—C4—H4B	108.5
C3^i—C1—H1A	120.8	O2—C5—O3	125.3 (3)
C3—C2—C1	121.2 (2)	O2—C5—C4	128.6 (3)
C3—C2—H2A	119.4	O3—C5—C4	106.1 (2)
C1—C2—H2A	119.4	O3—C6—H6A	109.5
C2—C3—O1	116.0 (2)	O3—C6—H6B	109.5
C2—C3—C1^i	120.4 (2)	H6A—C6—H6B	109.5
O1—C3—C1^i	123.5 (2)	O3—C6—H6C	109.5
O1—C4—C5	107.6 (2)	H6A—C6—H6C	109.5
O1—C4—H4A	110.2	H6B—C6—H6C	109.5
C3^i—C1—C2—C3	0.9 (4)	C3—O1—C4—C5	−175.2 (2)
C1—C2—C3—O1	178.9 (2)	C6—O3—C5—O2	−1.9 (4)
C1—C2—C3—C1^i	−0.9 (4)	C6—O3—C5—C4	178.7 (2)
C4—O1—C3—C2	175.4 (2)	O1—C4—C5—O2	−3.6 (4)
C4—O1—C3—C1^i	−4.8 (4)	O1—C4—C5—O3	175.74 (19)

Symmetry code: (i) −x+2, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6C···Cg1^ii	0.97	2.98	3.674 (2)	130

Symmetry code: (ii) −x+3/2, y−1/2, −z+1/2.