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Acta Cryst. (2009). E65, o1310    [ doi:10.1107/S1600536809017760 ]

Oxonium 2-carboxy-3-(2-furyl)acrylate

W.-X. Liang, G. Wang and Z.-R. Qu

Abstract top

In the title compound, H3O+·C8H5O5-, neighbouring cations and anions are linked by O-H...O hydrogen bonds, forming a one-dimensional chain framework along [001]. The crystal structure is further stabilized by [pi]-[pi] interactions, with centroid-centroid distances of 3.734 (3) Å.

Comment top

2-[(Furan-2-yl)methylene]malonic acid is a important bicarboxylic acid widely used in coordination chemistry and as an intermediate product in the synthesis of β-aminoacids. Recently, there has been an increased interest in the enantiomeric preparation of β-aminoacids as precursors for the synthesis of novel biologically active compounds (O'Callaghan et al., 1998; Cohen et al., 2002; Zeller et al., 1965). We report here the crystal structure of the title compound, which was prepared by the reaction of furan-2-carbaldehyde and malonic acid.

The asymmetric unit of the title compound (Fig.1) consists of a 2-[(furan-2-yl)methylene]malonate anion and a oxonium cation. The values of the C–O bond lengths in the carboxylic groups are consistent with a single bond character of the C8–O2 bond (1.308 (4)Å) and with a delocalized double bond character for the C7–O4 and C7–O5 bonds (1.262 (4) and 1.240 (4) Å, respectively). In the crystal packing (Fig. 2), classical intermolecular O—H···O hydrogen bonds connect neighbouring cations and anions, resulting in a one-dimensional chain framework along the c axis (Table 1). The crystal structure is further stabilized by π–π stacking interactions (Table 2) involving adjacent furane rings.

Related literature top

For the synthesis of β-aminoacids as precursors of novel biologically active compounds, see: O'Callaghan, et al. (1998); Cohen et al. (2002); Zeller et al. (1965).

Experimental top

A mixture of furan-2-carbaldehyde (0.5 mol, 0.48 g) and malonic acid (0.5 mol, 0.52 g) in ethanol (20 ml) was added in a flask and refluxed for 24 h. The resulting precipitate was separated and dissolved in an ethanol/water (5:1 v/v). Colourless single crystals of the title compound suitable for X-ray analysis were obtained on slow evaporation of the solvents over a period of 48 h.

Refinement top

The H atoms bound to O atoms were located in a difference Fourier map and refined with O—H = 0.82-0.85 Å and Uiso(H) = 1.5Uiso(O). All other H atoms were placed geometrically and allowed, with C—H = 0.93 Å and Uiso(H) = 1.2Uiso(C).

Computing details top

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL/PC (Sheldrick, 2008); software used to prepare material for publication: PRPKAPPA (Ferguson, 1999).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound with displacement ellipsoids drawn at the 30% probability level.
[Figure 2] Fig. 2. Packing diagram of the title compound viewed along the b axis. Hydrogen bonds are shown as dashed lines.
Oxonium 2-carboxy-3-(2-furyl)acrylate top
Crystal data top
H3O+·C8H5O5–F000 = 416
Mr = 200.14Dx = 1.508 Mg m−3
Monoclinic, P21/cMo Kα radiation
λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 1406 reflections
a = 13.664 (3) Åθ = 3.1–27.4º
b = 8.7518 (18) ŵ = 0.13 mm−1
c = 7.4664 (15) ÅT = 293 K
β = 99.13 (3)ºPrism, colourless
V = 881.5 (3) Å30.50 × 0.45 × 0.15 mm
Z = 4
Data collection top
Rigaku SCXmini
diffractometer		1727 independent reflections
Radiation source: fine-focus sealed tube1406 reflections with I > 2σ(I)
Monochromator: graphiteRint = 0.030
Detector resolution: 13.6612 pixels mm-1θmax = 26.0º
T = 293 Kθmin = 3.0º
CCD profile fitting scansh = −16→16
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2005)		k = −10→10
Tmin = 0.935, Tmax = 0.980l = −9→9
7954 measured reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.071  w = 1/[σ2(Fo2) + (0.1228P)2 + 1.0867P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.218(Δ/σ)max < 0.001
S = 1.06Δρmax = 0.46 e Å−3
1727 reflectionsΔρmin = −0.74 e Å−3
128 parametersExtinction correction: SHELXL97 (Sheldrick, 2008)
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.0014 (2)
Secondary atom site location: difference Fourier map
Crystal data top
H3O+·C8H5O5–V = 881.5 (3) Å3
Mr = 200.14Z = 4
Monoclinic, P21/cMo Kα
a = 13.664 (3) ŵ = 0.13 mm−1
b = 8.7518 (18) ÅT = 293 K
c = 7.4664 (15) Å0.50 × 0.45 × 0.15 mm
β = 99.13 (3)º
Data collection top
Rigaku SCXmini
diffractometer		1727 independent reflections
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2005)		1406 reflections with I > 2σ(I)
Tmin = 0.935, Tmax = 0.980Rint = 0.030
7954 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.071128 parameters
wR(F2) = 0.218H-atom parameters constrained
S = 1.06Δρmax = 0.46 e Å−3
1727 reflectionsΔρmin = −0.74 e Å−3
Special details top

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 (Å2) top
xyzUiso*/Ueq
C10.6364 (2)0.3648 (4)0.3879 (4)0.0326 (7)
C20.6705 (3)0.2258 (4)0.3518 (5)0.0471 (9)
H20.73340.20210.32750.057*
C30.5905 (3)0.1220 (4)0.3582 (6)0.0552 (10)
H30.59180.01680.34080.066*
C40.5149 (3)0.2026 (5)0.3932 (6)0.0548 (10)
H40.45300.16260.40320.066*
C50.6780 (2)0.5157 (3)0.4112 (4)0.0316 (7)
H50.63930.58940.45620.038*
C60.7666 (2)0.5621 (3)0.3751 (4)0.0294 (7)
C70.8392 (2)0.4604 (3)0.3007 (4)0.0281 (7)
C80.8008 (2)0.7221 (3)0.4080 (4)0.0299 (7)
O10.53944 (18)0.3521 (3)0.4129 (4)0.0502 (7)
O20.73994 (16)0.8126 (3)0.4760 (3)0.0389 (6)
H2A0.76940.89020.51530.058*
O30.88184 (17)0.7637 (3)0.3750 (3)0.0436 (7)
O40.84296 (16)0.4683 (2)0.1332 (3)0.0354 (6)
O50.89313 (18)0.3763 (3)0.4078 (3)0.0431 (6)
O1W0.9457 (2)0.4115 (3)0.7823 (4)0.0579 (8)
H1WC0.94630.41300.89630.087*
H1WA0.97970.33620.75490.087*
H1WB0.97030.49410.74950.087*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0310 (16)0.0324 (16)0.0356 (16)−0.0014 (12)0.0094 (12)0.0014 (12)
C20.0446 (19)0.0367 (19)0.059 (2)0.0089 (15)0.0065 (16)−0.0065 (16)
C30.068 (3)0.0307 (18)0.064 (2)−0.0096 (18)0.001 (2)−0.0026 (17)
C40.050 (2)0.048 (2)0.067 (3)−0.0196 (18)0.0112 (18)−0.0031 (19)
C50.0362 (17)0.0269 (15)0.0333 (15)0.0027 (12)0.0106 (12)−0.0005 (12)
C60.0336 (16)0.0230 (14)0.0319 (15)0.0023 (12)0.0062 (12)−0.0003 (11)
C70.0301 (15)0.0205 (13)0.0344 (16)−0.0016 (11)0.0074 (12)0.0002 (11)
C80.0331 (16)0.0250 (14)0.0318 (15)0.0008 (12)0.0061 (12)−0.0013 (12)
O10.0416 (14)0.0451 (15)0.0675 (17)−0.0090 (11)0.0199 (12)−0.0047 (12)
O20.0382 (12)0.0280 (11)0.0521 (14)0.0001 (9)0.0120 (10)−0.0121 (10)
O30.0409 (13)0.0333 (12)0.0602 (16)−0.0059 (10)0.0195 (11)−0.0077 (11)
O40.0447 (13)0.0290 (12)0.0352 (12)0.0061 (9)0.0149 (9)0.0025 (9)
O50.0481 (14)0.0401 (13)0.0397 (12)0.0148 (11)0.0030 (10)0.0027 (10)
O1W0.0586 (17)0.0583 (17)0.0589 (17)−0.0026 (14)0.0162 (13)0.0010 (13)
Geometric parameters (Å, °) top
C1—C21.345 (5)C6—C81.485 (4)
C1—O11.372 (4)C6—C71.503 (4)
C1—C51.437 (4)C7—O51.240 (4)
C2—C31.428 (6)C7—O41.262 (4)
C2—H20.9300C8—O31.226 (4)
C3—C41.311 (6)C8—O21.308 (4)
C3—H30.9300O2—H2A0.8200
C4—O11.352 (5)O1W—H1WC0.8500
C4—H40.9300O1W—H1WA0.8500
C5—C61.344 (4)O1W—H1WB0.8500
C5—H50.9300
C2—C1—O1109.0 (3)C5—C6—C8121.5 (3)
C2—C1—C5135.4 (3)C5—C6—C7124.3 (3)
O1—C1—C5115.5 (3)C8—C6—C7114.3 (2)
C1—C2—C3106.1 (3)O5—C7—O4123.9 (3)
C1—C2—H2126.9O5—C7—C6118.2 (3)
C3—C2—H2126.9O4—C7—C6117.8 (3)
C4—C3—C2107.2 (3)O3—C8—O2123.2 (3)
C4—C3—H3126.4O3—C8—C6121.1 (3)
C2—C3—H3126.4O2—C8—C6115.6 (3)
C3—C4—O1110.7 (3)C4—O1—C1107.0 (3)
C3—C4—H4124.7C8—O2—H2A109.5
O1—C4—H4124.7H1WC—O1W—H1WA109.5
C6—C5—C1127.2 (3)H1WC—O1W—H1WB109.5
C6—C5—H5116.4H1WA—O1W—H1WB109.5
C1—C5—H5116.4
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O1W—H1WB···O4i0.852.583.044 (4)115
O1W—H1WA···O3i0.852.423.188 (4)150
O1W—H1WC···O4ii0.852.483.201 (4)143
O2—H2A···O4iii0.821.742.552 (3)169
Symmetry codes: (i) −x+2, −y+1, −z+1; (ii) x, y, z+1; (iii) x, −y+3/2, z+1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
O1W—H1WB···O4i0.852.583.044 (4)115
O1W—H1WA···O3i0.852.423.188 (4)150
O1W—H1WC···O4ii0.852.483.201 (4)143
O2—H2A···O4iii0.821.742.552 (3)169
Symmetry codes: (i) −x+2, −y+1, −z+1; (ii) x, y, z+1; (iii) x, −y+3/2, z+1/2.
Table 2
π-π stacking interactions ( α is the dihedral angle between the planes, DCC is the length of the CC vector (centroid-to-centroid), τ is the angle subtended by the plane normal to CC. Cg1 is the centroid of the O1–C1/C4 ring) top
Group 1Group 2α /°DCC /Åτ /°
Cg1Cg1i16.423.734 (3)19.96
Symmetry code: (i) x, 1/2-y, -1/2+z
Acknowledgements top

This work was supported by the Technical Fund Financing Projects (No. 9207042464 and 9207041482) from Southeast University to ZRQ.

references
References top

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Zeller, E. A., Ramachander, G., Fleisher, G. A., Ishimaru, T. & Zeller, V. (1965). Biochem. J. 95, 262–269.