3,3,3-Trifluoro-2-hydr­oxy-2-(trifluoro­meth­yl)propionic acid

Gerber, T.; Betz, R.

doi:10.1107/S1600536813003103

organic compounds

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Volume 69| Part 3| March 2013| Page o335

doi:10.1107/S1600536813003103

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3,3,3-Trifluoro-2-hydroxy-2-(trifluoromethyl)propionic acid

Thomas Gerber ^a and Richard Betz ^a ^*

^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)

In the title perfluorinated hydroxyisobutyric acid derivative, C₄H₂F₆O₃, the molecule shows approximately C_s symmetry. The carboxy group is nearly coplanar with the C—OH moiety and the O=C—C—O(H) torsion angle is 5.5 (2)°. An intramolecular O—H⋯O hydrogen bond occurs. In the crystal, O—H⋯O hydrogen bonds connect the molecules into supramolecular chains along the a-axis direction.

Related literature

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

Crystal data

C₄H₂F₆O₃
M_r = 212.06
Orthorhombic, P 2₁ 2₁ 2₁
a = 5.9949 (2) Å
b = 6.4007 (2) Å
c = 18.5642 (6) Å
V = 712.34 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.26 mm⁻¹
T = 200 K
0.53 × 0.53 × 0.34 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2008 ) T_min = 0.908, T_max = 1.000
3824 measured reflections
1052 independent reflections
1024 reflections with I > 2σ(I)
R_int = 0.010

Refinement

R[F² > 2σ(F²)] = 0.029
wR(F²) = 0.076
S = 1.05
1052 reflections
120 parameters
H-atom parameters constrained
Δρ_max = 0.31 e Å⁻³
Δρ_min = −0.18 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O3—H3⋯O2	0.84	2.13	2.6274 (17)	118
O1—H1⋯O3ⁱ	0.84	1.91	2.7170 (17)	160
O3—H3⋯O2ⁱⁱ	0.84	2.06	2.7186 (17)	135
Symmetry codes: (i) x-1, y, z; (ii) $[x+{\script{1\over 2}}, -y+{\script{1\over 2}}, -z]$ .

Data collection: APEX2 (Bruker, 2010 ); cell refinement: SAINT (Bruker, 2010); data reduction: SAINT; 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 and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536813003103/tk5193sup1.cif

Supporting information file. DOI: 10.1107/S1600536813003103/tk5193Isup2.cdx

Structure factors: contains datablock I. DOI: 10.1107/S1600536813003103/tk5193Isup3.hkl

Supporting information file. DOI: 10.1107/S1600536813003103/tk5193Isup4.cml

checkCIF report

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 pK_a 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 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 O═C–C–O(H) torsion angle was found to be only 5.5 (2)°. This common plane also acts as internal mirror plane for the compound which shows approximately C_s symmetry (Fig. 1).

In the crystal, intermolecular hydrogen bonds can be observed. These are established between the carboxylic acid group as donor and the hydroxyl group as acceptor. The latter group itself, at the same time, acts as donor towards the double-bonded oxygen atom of the carboxyl group. The small dihedral angle among the O═C–C–O(H) moiety may be indicative of an intramolecular hydrogen bond as well, denoting the alcoholic hydroxyl group to give rise to a bifurcated hydrogen bond. 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 descriptor for the hydrogen bonds is S(5)C¹₁(5)C¹₁(5) on the unary level (Fig. 2).

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

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

	Fig. 1. The molecular structure of the title compound, with atom labels and anisotropic displacement ellipsoids (drawn at 50% probability level).
	Fig. 2. Intermolecular contacts, viewed along [0 0 - 1]. Blue dashed lines indicate intermolecular hydrogen bonds, yellow dashed lines indicate intramolecular hydrogen bonds. Symmetry operators: ⁱ x - 1, y, z; ⁱⁱ x - 1/2, -y + 1/2, -z; ⁱⁱⁱ x + 1/2, -y + 1/2, -z; ^iv x + 1x, y, z.
	Fig. 3. Molecular packing of the title compound, viewed along [0 1 0] (anisotropic displacement ellipsoids drawn at 50% probability level).

3,3,3-Trifluoro-2-hydroxy-2-(trifluoromethyl)propionic acid top

Crystal data top

C₄H₂F₆O₃	F(000) = 416
M_r = 212.06	D_x = 1.977 Mg m⁻³
Orthorhombic, P2₁2₁2₁	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 2971 reflections
a = 5.9949 (2) Å	θ = 4.4–28.3°
b = 6.4007 (2) Å	µ = 0.26 mm⁻¹
c = 18.5642 (6) Å	T = 200 K
V = 712.34 (4) Å³	Block, colourless
Z = 4	0.53 × 0.53 × 0.34 mm

Data collection top

Bruker APEXII CCD diffractometer	1052 independent reflections
Radiation source: fine-focus sealed tube	1024 reflections with I > 2σ(I)
Graphite monochromator	R_int = 0.010
ϕ and ω scans	θ_max = 28.3°, θ_min = 3.4°
Absorption correction: multi-scan (SADABS; Bruker, 2008)	h = −5→8
T_min = 0.908, T_max = 1.000	k = −6→8
3824 measured reflections	l = −22→24

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.029	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.076	H-atom parameters constrained
S = 1.05	w = 1/[σ²(F_o²) + (0.0385P)² + 0.2376P] where P = (F_o² + 2F_c²)/3
1052 reflections	(Δ/σ)_max < 0.001
120 parameters	Δρ_max = 0.31 e Å⁻³
0 restraints	Δρ_min = −0.18 e Å⁻³

Crystal data top

C₄H₂F₆O₃	V = 712.34 (4) Å³
M_r = 212.06	Z = 4
Orthorhombic, P2₁2₁2₁	Mo Kα radiation
a = 5.9949 (2) Å	µ = 0.26 mm⁻¹
b = 6.4007 (2) Å	T = 200 K
c = 18.5642 (6) Å	0.53 × 0.53 × 0.34 mm

Data collection top

Bruker APEXII CCD diffractometer	1052 independent reflections
Absorption correction: multi-scan (SADABS; Bruker, 2008)	1024 reflections with I > 2σ(I)
T_min = 0.908, T_max = 1.000	R_int = 0.010
3824 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.029	0 restraints
wR(F²) = 0.076	H-atom parameters constrained
S = 1.05	Δρ_max = 0.31 e Å⁻³
1052 reflections	Δρ_min = −0.18 e Å⁻³
120 parameters

Special details top

Refinement. Due to the absence of a strong anomalous scatterer, the Flack parameter is meaningless. Thus, Friedel opposites (636 pairs) have been merged and the item was removed from the CIF.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
F11	0.7286 (3)	0.2280 (3)	0.20540 (9)	0.0635 (5)
F12	0.6570 (2)	−0.0851 (3)	0.23660 (7)	0.0670 (5)
F13	0.99402 (19)	0.0068 (3)	0.21779 (6)	0.0464 (3)
F21	0.7614 (3)	−0.2907 (3)	0.02996 (9)	0.0702 (5)
F22	0.6292 (3)	−0.3692 (2)	0.13324 (12)	0.0747 (6)
F23	0.9814 (2)	−0.3310 (2)	0.11960 (9)	0.0527 (4)
O1	0.37188 (19)	−0.0103 (3)	0.11897 (8)	0.0403 (4)
H1	0.2541	0.0380	0.1010	0.060*
O2	0.5456 (2)	0.1808 (2)	0.03438 (8)	0.0372 (3)
O3	0.94390 (19)	0.0739 (2)	0.08055 (7)	0.0338 (3)
H3	0.8967	0.1464	0.0461	0.051*
C1	0.5428 (3)	0.0629 (3)	0.08432 (9)	0.0260 (3)
C2	0.7654 (3)	−0.0219 (3)	0.11475 (8)	0.0223 (3)
C3	0.7855 (3)	0.0308 (4)	0.19560 (10)	0.0340 (4)
C4	0.7833 (4)	−0.2590 (3)	0.10055 (12)	0.0382 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
F11	0.0602 (10)	0.0626 (9)	0.0677 (9)	0.0226 (9)	−0.0209 (8)	−0.0336 (7)
F12	0.0487 (8)	0.1198 (14)	0.0326 (6)	−0.0194 (10)	0.0099 (6)	0.0174 (8)
F13	0.0276 (5)	0.0770 (9)	0.0347 (5)	0.0062 (7)	−0.0112 (4)	0.0026 (7)
F21	0.0736 (10)	0.0738 (10)	0.0632 (8)	0.0260 (10)	−0.0204 (8)	−0.0368 (8)
F22	0.0546 (9)	0.0326 (6)	0.1368 (17)	−0.0094 (7)	0.0194 (11)	0.0087 (9)
F23	0.0412 (7)	0.0433 (7)	0.0735 (9)	0.0204 (6)	−0.0056 (7)	0.0015 (7)
O1	0.0129 (5)	0.0608 (9)	0.0473 (7)	0.0005 (6)	0.0007 (5)	0.0171 (8)
O2	0.0213 (5)	0.0479 (8)	0.0424 (7)	0.0020 (6)	−0.0061 (5)	0.0185 (6)
O3	0.0133 (5)	0.0512 (8)	0.0368 (6)	−0.0008 (6)	0.0012 (5)	0.0206 (6)
C1	0.0142 (7)	0.0332 (8)	0.0305 (7)	0.0003 (7)	−0.0022 (6)	0.0021 (7)
C2	0.0127 (6)	0.0287 (7)	0.0254 (6)	0.0005 (6)	0.0014 (5)	0.0054 (6)
C3	0.0223 (8)	0.0501 (11)	0.0295 (8)	0.0020 (9)	−0.0016 (6)	−0.0007 (8)
C4	0.0301 (9)	0.0329 (9)	0.0517 (11)	0.0049 (8)	−0.0019 (9)	−0.0029 (9)

Geometric parameters (Å, º) top

F11—C3	1.320 (3)	O1—H1	0.8400
F12—C3	1.313 (3)	O2—C1	1.196 (2)
F13—C3	1.325 (2)	O3—C2	1.3870 (19)
F21—C4	1.332 (3)	O3—H3	0.8400
F22—C4	1.312 (3)	C1—C2	1.547 (2)
F23—C4	1.322 (2)	C2—C3	1.543 (2)
O1—C1	1.297 (2)	C2—C4	1.544 (3)

C1—O1—H1	109.5	F12—C3—F13	107.93 (17)
C2—O3—H3	109.5	F11—C3—F13	108.19 (19)
O2—C1—O1	128.59 (16)	F12—C3—C2	113.24 (17)
O2—C1—C2	119.48 (15)	F11—C3—C2	108.83 (17)
O1—C1—C2	111.93 (13)	F13—C3—C2	110.55 (15)
O3—C2—C3	106.75 (14)	F22—C4—F23	108.76 (18)
O3—C2—C4	107.61 (15)	F22—C4—F21	107.7 (2)
C3—C2—C4	112.06 (15)	F23—C4—F21	107.36 (18)
O3—C2—C1	110.08 (12)	F22—C4—C2	113.62 (17)
C3—C2—C1	110.23 (14)	F23—C4—C2	111.08 (17)
C4—C2—C1	110.02 (15)	F21—C4—C2	108.10 (17)
F12—C3—F11	107.96 (19)

O2—C1—C2—O3	5.5 (2)	O3—C2—C3—F13	−44.9 (2)
O1—C1—C2—O3	−174.76 (17)	C4—C2—C3—F13	72.7 (2)
O2—C1—C2—C3	123.00 (19)	C1—C2—C3—F13	−164.42 (16)
O1—C1—C2—C3	−57.3 (2)	O3—C2—C4—F22	176.80 (17)
O2—C1—C2—C4	−112.92 (19)	C3—C2—C4—F22	59.8 (2)
O1—C1—C2—C4	66.81 (19)	C1—C2—C4—F22	−63.3 (2)
O3—C2—C3—F12	−166.13 (17)	O3—C2—C4—F23	53.8 (2)
C4—C2—C3—F12	−48.6 (2)	C3—C2—C4—F23	−63.2 (2)
C1—C2—C3—F12	74.3 (2)	C1—C2—C4—F23	173.74 (15)
O3—C2—C3—F11	73.80 (18)	O3—C2—C4—F21	−63.7 (2)
C4—C2—C3—F11	−168.63 (17)	C3—C2—C4—F21	179.21 (16)
C1—C2—C3—F11	−45.7 (2)	C1—C2—C4—F21	56.2 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O3—H3···O2	0.84	2.13	2.6274 (17)	118
O1—H1···O3ⁱ	0.84	1.91	2.7170 (17)	160
O3—H3···O2ⁱⁱ	0.84	2.06	2.7186 (17)	135

Symmetry codes: (i) x−1, y, z; (ii) x+1/2, −y+1/2, −z.

Experimental details

Crystal data
Chemical formula	C₄H₂F₆O₃
M_r	212.06
Crystal system, space group	Orthorhombic, P2₁2₁2₁
Temperature (K)	200
a, b, c (Å)	5.9949 (2), 6.4007 (2), 18.5642 (6)
V (Å³)	712.34 (4)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.26
Crystal size (mm)	0.53 × 0.53 × 0.34

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	Multi-scan (SADABS; Bruker, 2008)
T_min, T_max	0.908, 1.000
No. of measured, independent and observed [I > 2σ(I)] reflections	3824, 1052, 1024
R_int	0.010
(sin θ/λ)_max (Å⁻¹)	0.667

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.029, 0.076, 1.05
No. of reflections	1052
No. of parameters	120
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.31, −0.18

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···A	D—H	H···A	D···A	D—H···A
O3—H3···O2	0.84	2.13	2.6274 (17)	118
O1—H1···O3ⁱ	0.84	1.91	2.7170 (17)	160
O3—H3···O2ⁱⁱ	0.84	2.06	2.7186 (17)	135

Symmetry codes: (i) x−1, y, z; (ii) x+1/2, −y+1/2, −z.

Acknowledgements

The authors thank Mr Jamie Haner for helpful discussions.

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