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ISSN: 2056-9890

rac-3,3,3-Tri­fluoro­lactic acid

aNelson Mandela Metropolitan University, Summerstrand Campus, Department of Chemistry, University Way, Summerstrand, PO Box 77000, Port Elizabeth, 6031, South Africa
*Correspondence e-mail: richard.betz@webmail.co.za

(Received 29 January 2013; accepted 30 January 2013; online 2 February 2013)

The title compound (systematic name: rac-3,3,3-trifluoro-2-hy­droxy­propanoic acid), C3H3F3O3, is a fluorinated derivative of lactic acid. The O=C—C—O(H) torsion angle is 13.26 (15)°. In the crystal, O—H⋯O hydrogen bonds and C—H⋯O contacts connect the mol­ecules into sheets perpendicular to the c axis.

Related literature

For the crystal structure of 2-hy­droxy-2-(trifluoro­meth­yl)proprionic acid, see: Soloshonok et al. (2007[Soloshonok, V. A., Ueki, H., Yasumoto, M., Mekala, S., Hirschi, J. S. & Singleton, D. A. (2007). J. Am. Chem. Soc. 129, 12112-12113.]). For background to chelate ligands, see: Gade (1998[Gade, L. H. (1998). Koordinationschemie, 1. Auflage, Weinheim: Wiley-VCH.]). For graph-set analysis of hydrogen bonds, see: Etter et al. (1990[Etter, M. C., MacDonald, J. C. & Bernstein, J. (1990). Acta Cryst. B46, 256-262.]); Bernstein et al. (1995[Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555-1573.]).

[Scheme 1]

Experimental

Crystal data
  • C3H3F3O3

  • Mr = 144.05

  • Orthorhombic, P b c a

  • a = 10.586 (3) Å

  • b = 9.248 (3) Å

  • c = 10.826 (3) Å

  • V = 1059.9 (5) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 0.22 mm−1

  • T = 200 K

  • 0.40 × 0.30 × 0.25 mm

Data collection
  • Bruker APEXII CCD diffractometer

  • Absorption correction: multi-scan (SADABS; Bruker, 2008[Bruker (2008). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.]) Tmin = 0.892, Tmax = 1.000

  • 9450 measured reflections

  • 1309 independent reflections

  • 1133 reflections with I > 2σ(I)

  • Rint = 0.017

Refinement
  • R[F2 > 2σ(F2)] = 0.031

  • wR(F2) = 0.081

  • S = 1.06

  • 1309 reflections

  • 82 parameters

  • H-atom parameters constrained

  • Δρmax = 0.31 e Å−3

  • Δρmin = −0.19 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O3—H12⋯O2i 0.84 2.03 2.7459 (13) 143
O1—H111⋯O3ii 0.84 1.80 2.6381 (13) 172
C2—H12A⋯O1iii 1.00 2.60 3.4588 (16) 144
Symmetry codes: (i) -x, -y+1, -z+1; (ii) [x-{\script{1\over 2}}, -y+{\script{1\over 2}}, -z+1]; (iii) -x, -y, -z+1.

Data collection: APEX2 (Bruker, 2010[Bruker (2010). APEX2 and SAINT. Bruker AXS Inc., Madison, USA.]); cell refinement: SAINT (Bruker, 2010[Bruker (2010). APEX2 and SAINT. Bruker AXS Inc., Madison, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012[Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849-854.]) and Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009[Spek, A. L. (2009). Acta Cryst. D65, 148-155.]).

Supporting information


Comment top

Chelate ligands have found widespread use in coordination chemistry due to the increased stability of coordination compounds they can form in comparison to monodentate ligands (Gade, 1998). Hydroxycarboxylic acids are particularily interesting in this aspect as they offer two hydroxyl groups of markedly different acidity as potential bonding partners. Upon varying the substitution pattern on the hydrocarbon backbone, the acidity of the respective hydroxyl groups can be finetuned over a wide range and they may, thus, serve as probes for establishing the rules in which pKa range coordination to various central atoms can be observed. To allow for comparisons of metrical parameters of the carboxylic-acid-derived ligand in envisioned coordination compounds, the crystal and molecular structure of 3,3,3-trifluorolactic acid as the free ligand was determined. The crystal structure of a related compound, 2-hydroxy-2-(trifluoromethyl)proprionic acid, is apparent in the literature (Soloshonok et al., 2007).

The carboxyl group is nearly in plane with the C–OH moiety. The respective OC–C–O(H) dihedral angle was found at 13.26 (15) ° only (Fig. 1).

In the crystal, intra- as well as intermolecular hydrogen bonds are apparent. The former ones appear between the alcoholic hydroxyl group as donor and the ketonic oxygen atom as acceptor and, therefore, might be the cause for the small dihedral angle discussed above. The intermolecular hydrogen bonds are supported by the carboxyl group as donor and the alcoholic hydroxyl group as acceptor. In addition, C–H···O contacts whose range falls by more than 0.1 Å below the sum of van-der-Waals radii of the corresponding atoms can be observed. These stem from the hydrogen atom of the methine group and apply the oxygen atom of the carboxylic hydroxyl group as acceptor. Metrical parameters as well as information about the symmetry of these hydrogen bonds is summarized in Table 1. In terms of graph-set analysis (Etter et al., 1990; Bernstein et al., 1995), the descriptors for the hydrogen bonds are C11(5) and R22(10) on the unary level while the C–H···O contacts necessitate a R22(8) descriptor on the same level. In total, the intermolecular interactions connect the molecules to planes perpendicular to the crystallographic c axis (Fig. 2).

The packing of the title compound in the crystal structure is shown in Figure 3.

Related literature top

For the crystal structure of 2-hydroxy-2-(trifluoromethyl)proprionic acid, see: Soloshonok et al. (2007). For background to chelate ligands, see: Gade (1998). For graph-set analysis of hydrogen bonds, see: Etter et al. (1990); Bernstein et al. (1995).

Experimental top

The compound was obtained from Alfa Aesar. Crystals suitable for the diffraction study were taken directly from the provided product.

Refinement top

The carbon-bound H atom of the methine group was placed in a calculated position (C–H 1.00 Å) and was included in the refinement in the riding model approximation, with U(H) set to 1.2Ueq(C). The H atoms of the hydroxyl groups were allowed to rotate with a fixed angle around the C–O bond to best fit the experimental electron density (HFIX 147 in the SHELX program suite (Sheldrick, 2008)), with U(H) set to 1.5Ueq(O).

Computing details top

Data collection: APEX2 (Bruker, 2010); cell refinement: SAINT (Bruker, 2010); data reduction: SAINT (Bruker, 2010); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, with atom labels and anisotropic displacement ellipsoids (drawn at 50% probability level).
[Figure 2] Fig. 2. Intermolecular contacts, viewed along [0 0 - 1]. Blue dashed lines indicate hydrogen bonds, yellow dashed lines indicate C–H···O contacts. Symmetry operators: i -x, -y + 1, -z + 1; ii x - 1/2, -y + 1/2, -z + 1; iii x + 1/2, -y + 1/2, -z + 1; iv -x, -y, -z + 1.
[Figure 3] Fig. 3. Molecular packing of the title compound, viewed along [0 0 - 1] (anisotropic displacement ellipsoids drawn at 50% probability level).
rac-3,3,3-Trifluoro-2-hydroxypropanoic acid top
Crystal data top
C3H3F3O3F(000) = 576
Mr = 144.05Dx = 1.806 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 4117 reflections
a = 10.586 (3) Åθ = 3.5–28.2°
b = 9.248 (3) ŵ = 0.22 mm1
c = 10.826 (3) ÅT = 200 K
V = 1059.9 (5) Å3Platelet, colourless
Z = 80.40 × 0.30 × 0.25 mm
Data collection top
Bruker APEXII CCD
diffractometer
1309 independent reflections
Radiation source: fine-focus sealed tube1133 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.017
ϕ and ω scansθmax = 28.3°, θmin = 3.5°
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
h = 1410
Tmin = 0.892, Tmax = 1.000k = 1212
9450 measured reflectionsl = 1414
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: inferred from neighbouring sites
wR(F2) = 0.081H-atom parameters constrained
S = 1.06 w = 1/[σ2(Fo2) + (0.0349P)2 + 0.3452P]
where P = (Fo2 + 2Fc2)/3
1309 reflections(Δ/σ)max < 0.001
82 parametersΔρmax = 0.31 e Å3
0 restraintsΔρmin = 0.19 e Å3
Crystal data top
C3H3F3O3V = 1059.9 (5) Å3
Mr = 144.05Z = 8
Orthorhombic, PbcaMo Kα radiation
a = 10.586 (3) ŵ = 0.22 mm1
b = 9.248 (3) ÅT = 200 K
c = 10.826 (3) Å0.40 × 0.30 × 0.25 mm
Data collection top
Bruker APEXII CCD
diffractometer
1309 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2008)
1133 reflections with I > 2σ(I)
Tmin = 0.892, Tmax = 1.000Rint = 0.017
9450 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0310 restraints
wR(F2) = 0.081H-atom parameters constrained
S = 1.06Δρmax = 0.31 e Å3
1309 reflectionsΔρmin = 0.19 e Å3
82 parameters
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
F10.07491 (11)0.07334 (11)0.26362 (9)0.0698 (3)
F20.24046 (9)0.20543 (13)0.26938 (9)0.0670 (3)
F30.06121 (11)0.29936 (12)0.22550 (8)0.0661 (3)
O30.16058 (7)0.35907 (8)0.46617 (9)0.0346 (2)
H120.10840.42700.47310.052*
O10.10270 (7)0.12077 (8)0.45966 (9)0.0361 (2)
H1110.17900.13270.47820.054*
O20.09203 (7)0.35985 (8)0.48706 (9)0.0348 (2)
C10.04410 (10)0.24515 (11)0.46318 (10)0.0256 (2)
C20.09691 (10)0.23181 (11)0.43390 (10)0.0260 (2)
H12A0.13280.14990.48290.031*
C30.11835 (13)0.20173 (15)0.29671 (12)0.0398 (3)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
F10.0956 (8)0.0594 (6)0.0543 (6)0.0146 (5)0.0143 (5)0.0292 (5)
F20.0451 (5)0.1003 (8)0.0556 (5)0.0055 (5)0.0226 (4)0.0110 (5)
F30.0827 (7)0.0809 (7)0.0348 (5)0.0224 (6)0.0003 (4)0.0123 (4)
O30.0212 (4)0.0258 (4)0.0568 (5)0.0024 (3)0.0003 (3)0.0067 (4)
O10.0232 (4)0.0251 (4)0.0600 (6)0.0008 (3)0.0000 (4)0.0019 (4)
O20.0271 (4)0.0252 (4)0.0523 (5)0.0034 (3)0.0029 (4)0.0034 (3)
C10.0227 (5)0.0257 (5)0.0285 (5)0.0020 (4)0.0023 (4)0.0008 (4)
C20.0229 (5)0.0237 (5)0.0315 (5)0.0026 (4)0.0003 (4)0.0006 (4)
C30.0393 (7)0.0437 (7)0.0362 (6)0.0038 (5)0.0053 (5)0.0030 (5)
Geometric parameters (Å, º) top
F1—C31.3227 (17)O1—H1110.8399
F2—C31.3265 (17)O2—C11.2040 (13)
F3—C31.3325 (17)C1—C21.5310 (15)
O3—C21.4005 (13)C2—C31.5280 (17)
O3—H120.8400C2—H12A1.0000
O1—C11.3074 (13)
C2—O3—H12109.5C3—C2—H12A108.8
C1—O1—H111109.5C1—C2—H12A108.8
O2—C1—O1125.56 (10)F1—C3—F2107.55 (12)
O2—C1—C2121.76 (10)F1—C3—F3107.08 (12)
O1—C1—C2112.68 (9)F2—C3—F3107.21 (12)
O3—C2—C3108.91 (10)F1—C3—C2112.03 (11)
O3—C2—C1110.48 (8)F2—C3—C2110.91 (11)
C3—C2—C1111.15 (9)F3—C3—C2111.81 (11)
O3—C2—H12A108.8
O2—C1—C2—O313.26 (15)C1—C2—C3—F166.42 (14)
O1—C1—C2—O3166.37 (9)O3—C2—C3—F251.46 (14)
O2—C1—C2—C3107.76 (12)C1—C2—C3—F2173.40 (11)
O1—C1—C2—C372.61 (12)O3—C2—C3—F368.14 (13)
O3—C2—C3—F1171.65 (10)C1—C2—C3—F353.80 (14)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H12···O2i0.842.032.7459 (13)143
O1—H111···O3ii0.841.802.6381 (13)172
C2—H12A···O1iii1.002.603.4588 (16)144
Symmetry codes: (i) x, y+1, z+1; (ii) x1/2, y+1/2, z+1; (iii) x, y, z+1.

Experimental details

Crystal data
Chemical formulaC3H3F3O3
Mr144.05
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)200
a, b, c (Å)10.586 (3), 9.248 (3), 10.826 (3)
V3)1059.9 (5)
Z8
Radiation typeMo Kα
µ (mm1)0.22
Crystal size (mm)0.40 × 0.30 × 0.25
Data collection
DiffractometerBruker APEXII CCD
diffractometer
Absorption correctionMulti-scan
(SADABS; Bruker, 2008)
Tmin, Tmax0.892, 1.000
No. of measured, independent and
observed [I > 2σ(I)] reflections
9450, 1309, 1133
Rint0.017
(sin θ/λ)max1)0.666
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.031, 0.081, 1.06
No. of reflections1309
No. of parameters82
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.31, 0.19

Computer programs: APEX2 (Bruker, 2010), SAINT (Bruker, 2010), SHELXS97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012) and Mercury (Macrae et al., 2008), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O3—H12···O2i0.842.032.7459 (13)143.4
O1—H111···O3ii0.841.802.6381 (13)172.4
C2—H12A···O1iii1.002.603.4588 (16)144.1
Symmetry codes: (i) x, y+1, z+1; (ii) x1/2, y+1/2, z+1; (iii) x, y, z+1.
 

Acknowledgements

The authors thank Mr Ulf Breddemann of McMaster University, Canada, for helpful discussions.

References

First citationBernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem. Int. Ed. Engl. 34, 1555–1573.  CrossRef CAS Web of Science
First citationBruker (2008). SADABS. Bruker AXS Inc., Madison, Wisconsin, USA.
First citationBruker (2010). APEX2 and SAINT. Bruker AXS Inc., Madison, USA.
First citationEtter, M. C., MacDonald, J. C. & Bernstein, J. (1990). Acta Cryst. B46, 256–262.  CrossRef CAS Web of Science IUCr Journals
First citationFarrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854.  Web of Science CrossRef CAS IUCr Journals
First citationGade, L. H. (1998). Koordinationschemie, 1. Auflage, Weinheim: Wiley-VCH.
First citationMacrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470.  Web of Science CrossRef CAS IUCr Journals
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals
First citationSoloshonok, V. A., Ueki, H., Yasumoto, M., Mekala, S., Hirschi, J. S. & Singleton, D. A. (2007). J. Am. Chem. Soc. 129, 12112–12113.  Web of Science CSD CrossRef PubMed CAS
First citationSpek, A. L. (2009). Acta Cryst. D65, 148–155.  Web of Science CrossRef CAS IUCr Journals

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