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Volume 61 
Part 8 
Pages o2422-o2423  
August 2005  

Received 20 May 2005
Accepted 3 June 2005
Online 9 July 2005

Key indicators
Single-crystal X-ray study
T = 150 K
Mean [sigma](C-C) = 0.002 Å
Disorder in main residue
R = 0.036
wR = 0.095
Data-to-parameter ratio = 12.7
Details

Methyl acetoacetate at 150 K

aChemical Crystallography Laboratory, Chemistry Research Laboratory, Mansfield Road, Oxford University, Oxford OX1 3TA, England
Correspondence e-mail: howard.shallard-brown@lmh.ox.ac.uk

The crystal structure of methyl acetoacetate, C5H8O3, at 150 K contains discrete molecules.

Comment

Many of the esters and ketones used in the flavours and fragrances industry are liquid at room temperature, meaning that in the past crystalline derivatives have had to be prepared for X-ray analysis. As part of a programme to systematize in situ crystal growth from liquids, we have examined a range of commercially available chemicals. Low-molecular-weight organic ketones are liquid at room temperature. Molecules of methyl acetoacetate, (I)[link], exist as discrete entities in the crystal structure at 150 K, with no strong intermolecular interactions.

[Scheme 1]
[Figure 1]
Figure 1
The title compound, with displacement ellipsoids drawn at the 50% probability level. H atoms are of arbitrary radii.
[Figure 2]
Figure 2
The crystal structure, viewed down the a axis.
[Figure 3]
Figure 3
The crystal structure, viewed down the b axis.

Experimental

A 3 mm column of the title material, which is a liquid at room temperature, was sealed in a 0.3 mm Lindemann tube. The Lindemann tube was not precisely parallel to the [varphi] axis. A single crystal of the compound was grown by keeping the sample under a stream of nitrogen gas (Oxford Cryostream 600) at 180 K and slowly moving a small liquid zone, created by a micro-heating coil, up and down the sample. Once a suitable approximately single-crystal specimen had been obtained, the main data collection was carried out at 150 K. Because not all the data were collected with the Lindemann tube perpendicular to the X-ray beam, the multi-scan corrections applied by DENZO/SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]) also contain contributions due to changes in the illuminated volume of the cylindrical sample, which affects the value of Tmin/Tmax.

Crystal data
  • C5H8O3

  • Mr = 116.12

  • Monoclinic, P 121 /c 1

  • a = 6.0018 (2) Å

  • b = 8.0384 (3) Å

  • c = 12.4802 (3) Å

  • [beta] = 95.5132 (17)°

  • V = 599.32 (3) Å3

  • Z = 4

  • Dx = 1.287 Mg m-3

  • Mo K[alpha] radiation

  • Cell parameters from 1392 reflections

  • [theta] = 5-27°

  • [mu] = 0.11 mm-1

  • T = 150 K

  • Cylinder, colourless

  • 0.70 × 0.30 × 0.30 mm

Data collection
  • Nonius KappaCCD diffractometer

  • [omega] scans

  • Absorption correction: multi-scan(DENZO/SCALEPACK; Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.])Tmin = 0.68, Tmax = 0.95

  • 2531 measured reflections

  • 1343 independent reflections

  • 1184 reflections with I > 2[sigma](I)

  • Rint = 0.022

  • [theta]max = 27.5°

  • h = -7 [rightwards arrow] 7

  • k = -10 [rightwards arrow] 10

  • l = -16 [rightwards arrow] 16

Refinement
  • Refinement on F2

  • R[F2 > 2[sigma](F2)] = 0.036

  • wR(F2) = 0.095

  • S = 1.01

  • 1343 reflections

  • 106 parameters

  • Only H-atom coordinates refined

  • w = 1/[[sigma]2(F) + 0.04 + 0.19P] where P = [max(Fo2, 0) + 2Fc2]/3

  • ([Delta]/[sigma])max < 0.001

  • [Delta][rho]max = 0.25 e Å-3

  • [Delta][rho]min = -0.22 e Å-3

Table 1
Selected geometric parameters (Å, °)[link]

C1-C2 1.5001 (15)
C1-O6 1.3328 (14)
C1-O8 1.1997 (14)
C2-C3 1.5191 (15)
C3-O4 1.2118 (13)
C3-C5 1.4920 (15)
O6-C7 1.4458 (14)
C2-C1-O6 111.96 (9)
C2-C1-O8 124.51 (11)
O6-C1-O8 123.53 (10)
C1-C2-C3 112.28 (9)
C2-C3-O4 121.15 (10)
C2-C3-C5 115.27 (9)
O4-C3-C5 123.58 (10)
C1-O6-C7 116.27 (9)

All H atoms were located in a difference map. Alternative positions were clearly visible for the disordered H atoms on C7, whose site occupancy factors were set to 0.5. The H atoms were then repositioned geometrically and refined with soft restraints on the bond lengths and angles to regularize their geometry, with C-H = 0.97-1.01 Å, and Uiso(H) = 1.2Ueq(C), after which the restraints were removed.

Data collection: COLLECT (Nonius, 1997[Nonius (1997). COLLECT. Nonius BV, Delft, The Netherlands.]); cell refinement: DENZO/SCALEPACK (Otwinowski & Minor, 1997[Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.]); data reduction: DENZO/SCALEPACK; program(s) used to solve structure: SIR92 (Altomare et al., 1994[Altomare, A., Cascarano, G., Giacovazzo, G., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.]); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003[Betteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487.]); molecular graphics: CAMERON (Watkin et al., 1996[Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England.]); software used to prepare material for publication: CRYSTALS.

References

Altomare, A., Cascarano, G., Giacovazzo, G., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435. [details]
Betteridge, P. W., Carruthers, J. R., Cooper, R. I., Prout, K. & Watkin, D. J. (2003). J. Appl. Cryst. 36, 1487. [details]
Nonius (1997). COLLECT. Nonius BV, Delft, The Netherlands.
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276, Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M. Sweet, pp. 307-326. New York: Academic Press.
Watkin, D. J., Prout, C. K. & Pearce, L. J. (1996). CAMERON. Chemical Crystallography Laboratory, Oxford, England.


Acta Cryst (2005). E61, o2422-o2423   [ doi:10.1107/S1600536805017654 ]