Oxacyclo­hexane-2,6-dione (glutaric anhydride)

In the title compound, C₅H₆O₃, the ring adopts a slightly distorted envelope conformation. Adjacent mol­ecules are linked via weak C—H...O contacts. Two phase transitions at temperatures of 154/183 and 172/192 K are observed for the title compound in a differential scanning calorimetry experiment; these occur below the structure determination temperature of 240 K.

Key indicators

• Single-crystal X-ray study
• T = 240 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.041
• wR factor = 0.116
• Data-to-parameter ratio = 10.6

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT180_ALERT_3_C Check Cell Rounding: # of Values Ending with 0 =          3

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           28.45
           From the CIF: _reflns_number_total                774
           Count of symmetry unique reflns          816
           Completeness (_total/calc)             94.85%
           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
   0 ALERT level B = Potentially serious problem
   1 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
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S1. Comment

The title compound (I) (Fig. 1) and some of its derivatives are commonly used as reagents in the organic synthesis (Freer et al., 1988; Takahashi et al., 2004). Several papers concerning the crystal state studies of glutaric anhydride derivatives, as 3-phenyl-1-oxacyclohexane-2,6-dione or β-chloroglutaric acid anhydride are available in the literature (Koer et al., 1972; Bocelli & Grenier-Loustalot, 1982), but surprisingly the crystal structure of the glutaric anhydride has not been determined yet.

This paper reports the crystal state studies of the glutaric anhydride. Compound I crystallizes in the i>P2₁2₁2₁ space group with one independent molecule in the asymmetric unit.

The C1=O3 and C5=O2 bond lengths of 1.197 (3) Å and 1.188 (3) Å, respectively, remain in good agreement with those C=O bond lengths observed in related compounds crystal structures (Koer et al., 1972; Bocelli & Grenier-Loustalot, 1982; Qian et al., 2006). The differences in the C=O bonds lengths existing between discussed structures are similar to those observed for two independent molecules of β-chloroglutaric acid anhydride (Koer et al., 1972) and can be justified by the different intermolecular interactions, present in the crystal network. The C1—O1—C3 angle of 124.5 (2)° remains also in agreement with the numerous literature data (Koer et al., 1972; Bocelli & Grenier-Loustalot, 1982; Bertolasi et al., 1997; Qian et al., 2006). The six-membered ring of glutaric anhydride molecule adopts nearly envelope conformation, what is confirmed by the values of puckering parameters: q₂ = 0.375 (2) Å, q₃ = 0.251 (2) Å and ψ₂= 174.5 (4)° (Cremer & Pople, 1975) for the O1/C1/C2/C3/C4/C5 ring atom sequence. The O1, C1, C2, C4 and C5 atoms are coplanar (r.m.s. deviation = 0.0188), and C3 carbon is deviated from the plane defined by above atoms by -0.625 (4) Å.

In glutaric anhydride crystal structure no hydrogen bonds are observed. Only very weak interactions as C—H···O contacts between adjacent molecules can be recognized (Table 2). Molecular packing (Fig. 2), which exists in the glutaric anhydride crystals can explain the low value of the melting point.

Related literature

For related literature, see: Bertolasi et al. (1997); Bocelli & Grenier-Loustalot (1982); Cremer & Pople (1975); Freer et al. (1988); Koer et al. (1972); Qian et al. (2006); Stefanowicz (2006); Takahashi et al. (2004).

For related literature, see: Burnett & Johnson (1996); Farrugia (1997).

S2. Experimental

The title compound was obtained (Stefanowicz, 2006) by the dehydratation of the glutaric acid in the acetic anhydride solution. The glutaric acid (30 g; 0,227 mol) was added to the 25 ml of the acetic anhydride. Obtained mixture was heated slowly until the boiling point was reached, and then refluxed for 15 minutes. Later the solvent was removed in a vacuo. Treatment of the obtained oil residue with naphthyl ether (200 ml) and later washing with the n-hexane resulted in the single crystals suitable for X-ray measurements. Glutaric anhydride undergoes the phase transitions, what was confirmed by the DSC technique. DSC studies on (I) disclosed two closely laying phase transitions at 154/183 K (cooling-heating) and 172/192 K. These phase transitions characterized by a significant temperature hysteresis may be classified as discontinuous ones. They are accompanied by a relatively small entropy effects: ΔS = 0.36 J/(mol K) and 0.20 J/(mol K).

S3. Refinement

The structure was solved by direct methods with using SHELXS97. The H atoms were placed in the idealized positions as riding on their parent atoms with distances of 0.98 Å with U_iso(H) values of 1.2U_eq(C). Although the molecule is achiral, the structure possesses a polar axis. The absence of atoms, which possess the atomic number higher than silicon causes that no anomoulus dispersion is observed. The Flack [(1983). Acta Cryst. A39, 876–881] parameter is meanigless in this case. The absolute direction of the polar axis was assigned arbitrarily and the Friedel pairs were merged before the final refinement.

Computing details

Data collection: CrysAlis CCD (Oxford Diffraction, 2003); cell refinement: CrysAlis RED (Oxford Diffraction, 2003); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003) and XP (Bruker, 1999); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. ORTEP atom numbering scheme of I. The thermal ellipsoides were drawn at 20% probability.
	Fig. 2. The view of the packing of I, viewed along the a axis. Atom O2 is at (1 - x,-1/2 + y,3/2 - z).

Oxacyclohexane-2,6-dione

Crystal data

C5H6O3	F(000) = 240
Mr = 114.10	Dx = 1.413 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 668 reflections
a = 5.410 (4) Å	θ = 3.1–28.5°
b = 7.520 (6) Å	µ = 0.12 mm^−1
c = 13.180 (8) Å	T = 240 K
V = 536.2 (7) Å^3	Needle, colourless
Z = 4	0.53 × 0.15 × 0.15 mm

Data collection

KUMA KM-4 CCD κ-geometry diffractometer	668 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.034
Graphite monochromator	θmax = 28.5°, θmin = 3.1°
ω and φ scans	h = −7→5
3600 measured reflections	k = −9→10
774 independent reflections	l = −17→16

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)] = 0.041	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.116	H-atom parameters constrained
S = 1.14	w = 1/[σ^2(Fo^2) + (0.0681P)^2 + 0.0184P] where P = (Fo^2 + 2Fc^2)/3
774 reflections	(Δ/σ)max < 0.001
73 parameters	Δρmax = 0.22 e Å^−3
0 restraints	Δρmin = −0.11 e Å^−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.5092 (2)	0.6331 (2)	0.60650 (11)	0.0495 (4)
C1	0.5835 (4)	0.5529 (3)	0.51710 (16)	0.0471 (5)
O3	0.4401 (3)	0.5620 (2)	0.44814 (12)	0.0712 (6)
C2	0.8311 (4)	0.4690 (3)	0.51408 (16)	0.0504 (5)
H2A	0.9512	0.5552	0.4880	0.060*
H2B	0.8270	0.3681	0.4671	0.060*
C5	0.6538 (4)	0.6438 (3)	0.69384 (16)	0.0517 (5)
O2	0.5715 (4)	0.7309 (3)	0.76100 (13)	0.0813 (7)
C4	0.8970 (4)	0.5521 (3)	0.69368 (16)	0.0530 (5)
H4A	0.9273	0.5026	0.7613	0.064*
H4B	1.0269	0.6398	0.6799	0.064*
C3	0.9151 (4)	0.4048 (3)	0.61660 (17)	0.0545 (6)
H3A	1.0865	0.3634	0.6122	0.065*
H3B	0.8121	0.3044	0.6381	0.065*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0396 (7)	0.0576 (9)	0.0512 (8)	0.0085 (7)	0.0013 (6)	−0.0010 (7)
C1	0.0472 (10)	0.0467 (10)	0.0475 (10)	−0.0027 (10)	−0.0023 (9)	0.0008 (9)
O3	0.0670 (11)	0.0888 (13)	0.0577 (10)	0.0057 (11)	−0.0200 (9)	−0.0027 (9)
C2	0.0518 (12)	0.0504 (11)	0.0489 (11)	0.0006 (10)	0.0030 (10)	−0.0099 (10)
C5	0.0465 (10)	0.0605 (13)	0.0479 (11)	0.0054 (10)	0.0058 (10)	−0.0034 (11)
O2	0.0701 (12)	0.1111 (15)	0.0627 (11)	0.0210 (12)	0.0087 (10)	−0.0317 (11)
C4	0.0471 (11)	0.0664 (13)	0.0455 (10)	0.0088 (11)	−0.0034 (9)	0.0005 (11)
C3	0.0493 (11)	0.0535 (12)	0.0606 (12)	0.0103 (10)	0.0033 (11)	0.0022 (10)

Geometric parameters (Å, º)

O1—C1	1.383 (3)	C5—O2	1.188 (3)
O1—C5	1.394 (3)	C5—C4	1.485 (3)
C1—O3	1.197 (3)	C4—C3	1.506 (3)
C1—C2	1.481 (3)	C4—H4A	0.9800
C2—C3	1.505 (3)	C4—H4B	0.9800
C2—H2A	0.9800	C3—H3A	0.9800
C2—H2B	0.9800	C3—H3B	0.9800
C1—O1—C5	124.43 (15)	C5—C4—C3	113.55 (18)
O3—C1—O1	115.69 (19)	C5—C4—H4A	108.9
O3—C1—C2	126.2 (2)	C3—C4—H4A	108.9
O1—C1—C2	118.13 (17)	C5—C4—H4B	108.9
C1—C2—C3	112.67 (19)	C3—C4—H4B	108.9
C1—C2—H2A	109.1	H4A—C4—H4B	107.7
C3—C2—H2A	109.1	C2—C3—C4	110.50 (18)
C1—C2—H2B	109.1	C2—C3—H3A	109.6
C3—C2—H2B	109.1	C4—C3—H3A	109.6
H2A—C2—H2B	107.8	C2—C3—H3B	109.6
O2—C5—O1	115.9 (2)	C4—C3—H3B	109.6
O2—C5—C4	126.1 (2)	H3A—C3—H3B	108.1
O1—C5—C4	117.99 (18)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C3—H3B···O2^i	0.98	2.53	3.353 (4)	142

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