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The title compound, C4H4O2, was prepared as an inter­mediate in the synthesis of α-hydroxy­cyclo­propane­carboxylic acid. The structure of this inter­mediate has only been deduced previously from 1H NMR spectra, elemental analysis or chemical derivatization. A single-crystal X-ray analysis was carried out to unambiguously assign the correct structure. The cyclo­butane ring is almost planar.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807042924/nc2049sup1.cif
Contains datablocks I, global

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807042924/nc2049Isup2.hkl
Contains datablock I

CCDC reference: 663706

Key indicators

  • Single-crystal X-ray study
  • T = 200 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.031
  • wR factor = 0.081
  • Data-to-parameter ratio = 9.9

checkCIF/PLATON results

No syntax errors found



Alert level B PLAT432_ALERT_2_B Short Inter X...Y Contact O2 .. C1 .. 2.91 Ang.
Author Response: Carbonyl-carbonyl interaction features short O...C contact. (see Allen et al. (1998) B54, 320-329)

Alert level C PLAT369_ALERT_2_C Long C(sp2)-C(sp2) Bond C1 - C2 ... 1.56 Ang.
Author Response: C-C bond in -C(=O)-C(=O)- system under consideration
PLAT432_ALERT_2_C Short Inter X...Y Contact  O1     ..  C2      ..       2.99 Ang.
Author Response: Carbonyl-carbonyl interaction features short O...C contact. (see Allen et al. (1998) B54, 320-329)
PLAT432_ALERT_2_C Short Inter X...Y Contact  O1     ..  C1      ..       3.00 Ang.
Author Response: Carbonyl-carbonyl interaction features short O...C contact. (see Allen et al. (1998) B54, 320-329)

Alert level G REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF. From the CIF: _diffrn_reflns_theta_max 27.48 From the CIF: _reflns_number_total 557 Count of symmetry unique reflns 559 Completeness (_total/calc) 99.64% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 0 Fraction of Friedel pairs measured 0.000 Are heavy atom types Z>Si present no
0 ALERT level A = In general: serious problem 1 ALERT level B = Potentially serious problem 3 ALERT level C = Check and explain 1 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 4 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

Comment top

The title compound, C4H4O2, was prepared as an intermediate in the synthesis of α-hydroxycyclopropanecarboxylic acid. In the crystal structure the cyclobutane ring is almost planar (Fig. 1).

Related literature top

Details of the synthesis of the title compound were given by Heine (1971). For related literature, see: Flack (1983).

Experimental top

The title compound was prepared according to a published procedure (Heine, 1971) by reaction of bromine on 1,2-bis(trimethylsilyloxy)-cyclobut-1,2-ene in n-pentane. Crystals were obtained upon warming to room temperature and storage of the reaction batch at ambient temperature under exclusion of light for 72 h.

Spectroscopic data: 1H NMR (399.8 MHz, CDCl3, 24 °C) δ/p.p.m.: 3.07 (s, 4 H, CH2). 13C{1H} NMR (100.5 MHz, CDCl3, 26 °C) δ/p.p.m.: 207.3 (CO), 41.8 (CH2).

Refinement top

All H atoms were located in a difference map and refined as riding on their parent atoms. One common isotropic displacement parameter for all H atoms was refined to Uiso(H) = 0.048 (3) Å2.

Due to the absence of significant anomalous scattering the absolute structure factor (Flack, 1983), which is 2.9 with an estimated standard deviation of 2 for the unmerged data set, is meaningless. Thus, Friedel opposites (351 pairs) have been merged. The absolute structure has been arbitrarily chosen.

Structure description top

The title compound, C4H4O2, was prepared as an intermediate in the synthesis of α-hydroxycyclopropanecarboxylic acid. In the crystal structure the cyclobutane ring is almost planar (Fig. 1).

Details of the synthesis of the title compound were given by Heine (1971). For related literature, see: Flack (1983).

Computing details top

Data collection: Collect (Bruker–Nonius, 2004); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997).

Figures top
[Figure 1] Fig. 1. The molecular structure of (I), with atom labels and anisotropic displacement ellipsoids (drawn at 50% probability level) for non-H atoms.
Cyclobutane-1,2-dione top
Crystal data top
C4H4O2F(000) = 176
Mr = 84.07Dx = 1.394 Mg m3
Orthorhombic, P212121Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2abCell parameters from 5161 reflections
a = 5.3719 (3) Åθ = 3.1–27.5°
b = 6.8819 (3) ŵ = 0.11 mm1
c = 10.8378 (6) ÅT = 200 K
V = 400.66 (4) Å3Block, yellow–orange
Z = 40.20 × 0.17 × 0.14 mm
Data collection top
Nonius KappaCCD
diffractometer
488 reflections with I > 2σ(I)
Radiation source: rotating anodeRint = 0.038
MONTEL, graded multilayered X-ray optics monochromatorθmax = 27.5°, θmin = 3.5°
CCD; rotation images; thick slices scansh = 66
3074 measured reflectionsk = 88
557 independent reflectionsl = 1314
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.031Hydrogen site location: difference Fourier map
wR(F2) = 0.081Only H-atom displacement parameters refined
S = 1.09 w = 1/[σ2(Fo2) + (0.0567P)2 + 0.294P]
where P = (Fo2 + 2Fc2)/3
557 reflections(Δ/σ)max < 0.001
56 parametersΔρmax = 0.12 e Å3
0 restraintsΔρmin = 0.15 e Å3
Crystal data top
C4H4O2V = 400.66 (4) Å3
Mr = 84.07Z = 4
Orthorhombic, P212121Mo Kα radiation
a = 5.3719 (3) ŵ = 0.11 mm1
b = 6.8819 (3) ÅT = 200 K
c = 10.8378 (6) Å0.20 × 0.17 × 0.14 mm
Data collection top
Nonius KappaCCD
diffractometer
488 reflections with I > 2σ(I)
3074 measured reflectionsRint = 0.038
557 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0310 restraints
wR(F2) = 0.081Only H-atom displacement parameters refined
S = 1.09Δρmax = 0.12 e Å3
557 reflectionsΔρmin = 0.15 e Å3
56 parameters
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
O10.0632 (3)0.2198 (2)0.25237 (14)0.0496 (4)
O20.0783 (3)0.42078 (19)0.51173 (12)0.0429 (4)
C10.1626 (4)0.3358 (2)0.31712 (16)0.0327 (4)
C20.0924 (3)0.4362 (2)0.44147 (14)0.0310 (4)
C30.3323 (4)0.5531 (3)0.43585 (16)0.0359 (4)
H310.44770.52560.50490.048 (3)*
H320.30510.69470.42670.048 (3)*
C40.4048 (4)0.4512 (3)0.31457 (16)0.0358 (4)
H410.41810.54080.24340.048 (3)*
H420.55550.36930.32160.048 (3)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
O10.0511 (9)0.0464 (8)0.0513 (7)0.0045 (8)0.0136 (9)0.0149 (7)
O20.0370 (7)0.0500 (8)0.0416 (7)0.0022 (7)0.0056 (7)0.0056 (6)
C10.0340 (9)0.0310 (8)0.0331 (8)0.0007 (8)0.0038 (8)0.0012 (7)
C20.0303 (9)0.0314 (8)0.0311 (8)0.0020 (8)0.0043 (8)0.0029 (7)
C30.0328 (9)0.0337 (9)0.0413 (9)0.0030 (8)0.0033 (8)0.0053 (8)
C40.0338 (9)0.0356 (9)0.0380 (8)0.0026 (8)0.0028 (8)0.0031 (8)
Geometric parameters (Å, º) top
O1—C11.190 (2)C3—C41.540 (2)
O2—C21.196 (2)C3—H310.9900
C1—C41.524 (3)C3—H320.9900
C1—C21.561 (2)C4—H410.9900
C2—C31.520 (3)C4—H420.9900
O1—C1—C4136.23 (18)C2—C3—H32113.6
O1—C1—C2134.26 (18)C4—C3—H32113.6
C4—C1—C289.50 (13)H31—C3—H32110.8
O2—C2—C3136.21 (16)C1—C4—C390.33 (14)
O2—C2—C1134.07 (17)C1—C4—H41113.6
C3—C2—C189.70 (13)C3—C4—H41113.6
C2—C3—C490.44 (13)C1—C4—H42113.6
C2—C3—H31113.6C3—C4—H42113.6
C4—C3—H31113.6H41—C4—H42110.9
O1—C1—C2—O23.7 (4)C1—C2—C3—C41.11 (12)
C4—C1—C2—O2177.2 (2)O1—C1—C4—C3178.0 (2)
O1—C1—C2—C3178.0 (2)C2—C1—C4—C31.11 (12)
C4—C1—C2—C31.12 (12)C2—C3—C4—C11.14 (13)
O2—C2—C3—C4177.2 (2)

Experimental details

Crystal data
Chemical formulaC4H4O2
Mr84.07
Crystal system, space groupOrthorhombic, P212121
Temperature (K)200
a, b, c (Å)5.3719 (3), 6.8819 (3), 10.8378 (6)
V3)400.66 (4)
Z4
Radiation typeMo Kα
µ (mm1)0.11
Crystal size (mm)0.20 × 0.17 × 0.14
Data collection
DiffractometerNonius KappaCCD
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
3074, 557, 488
Rint0.038
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.031, 0.081, 1.09
No. of reflections557
No. of parameters56
H-atom treatmentOnly H-atom displacement parameters refined
Δρmax, Δρmin (e Å3)0.12, 0.15

Computer programs: Collect (Bruker–Nonius, 2004), HKL SCALEPACK (Otwinowski & Minor, 1997), HKL DENZO and SCALEPACK (Otwinowski & Minor, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEPIII (Burnett & Johnson, 1996).

 

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