2-(Trifluoro­meth­yl)benzoic acid

Betz, R.; Gerber, T.

doi:10.1107/S1600536811009597

organic compounds

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Volume 67| Part 4| April 2011| Page o907

doi:10.1107/S1600536811009597

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2-(Trifluoromethyl)benzoic acid

Richard Betz ^a ^* and Thomas Gerber ^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 21 February 2011; accepted 14 March 2011; online 19 March 2011)

In the title compound, C₈H₅F₃O₂, a halogenated derivative of benzoic acid, the carboxyl group is tilted by 16.8 (3)° with respect to the plane of the aromatic ring. In the crystal, O—H⋯O hydrogen bonding gives rise to carboxylic acid dimers, which are further connected into double chains along [1,1/4,1] by C—H⋯O contacts. C—H⋯F and C—F⋯π contacts are also observed.

Related literature

For the crystal structure of benzoic acid using X-ray diffraction, see Bruno & Randaccio (1980 ). For the crystal structure of benzoic acid applying neutron radiation, see Wilson et al. (1996 ), and of ortho-fluorobenzoic acid, see Krausse & Dunken (1966 ). For the crystal structure of ortho-chlorobenzoic acid, see Ferguson & Sim (1961 ); Polito et al. (2008 ). For graph-set analysis of hydrogen bonds, see: Etter et al. (1990 ); Bernstein et al. (1995 ).

Experimental

Crystal data

C₈H₅F₃O₂
M_r = 190.12
Monoclinic, P 2₁ /c
a = 4.8816 (3) Å
b = 20.6948 (14) Å
c = 7.9697 (5) Å
β = 109.544 (4)°
V = 758.74 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.17 mm⁻¹
T = 200 K
0.50 × 0.50 × 0.09 mm

Data collection

Bruker APEXII CCD diffractometer
7115 measured reflections
1889 independent reflections
1548 reflections with I > 2σ(I)
R_int = 0.048

Refinement

R[F² > 2σ(F²)] = 0.049
wR(F²) = 0.113
S = 1.06
1889 reflections
119 parameters
H-atom parameters constrained
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.33 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

Cg is the centroid of the C2–C7 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1⋯O2ⁱ	0.84	1.81	2.6459 (19)	173
C6—H6⋯O2ⁱⁱ	0.95	2.66	3.590 (3)	167
C6—H6⋯F3ⁱⁱ	0.95	2.63	3.303 (3)	128
C7—H7⋯O1ⁱⁱⁱ	0.95	2.66	3.411 (2)	137
C8—F1⋯Cg^iv	1.34 (1)	3.48 (1)	4.806 (2)	170 (1)
Symmetry codes: (i) -x+3, -y, -z+1; (ii) x-1, y, z-1; (iii) -x+2, -y, -z; (iv) $[x, -y-{\script{1\over 2}}, z-{\script{1\over 2}}]$ .

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 (Farrugia, 1997 ) and Mercury (Macrae et al., 2006 ); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ).

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811009597/fl2339sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536811009597/fl2339Isup2.hkl

checkCIF report

Comment top

Benzoic acid has found widespread use as a ligand in coordination chemistry for a variety of transition metals and elements from the s- and p-block of the periodic system of the elements. It can act as a neutral or – upon deprotonation – an anionic ligand and serve as mono- or bidentate ligand. By varying the substituents on the phenyl moiety, the acidity of the carboxylic acid group can be fine-tuned. Particular interest rests in benzoic acid derivatives showing an asymmetric pattern of substituents on the aromatic moiety due to different possible orientations of the ligand in coordination compounds and the possible formation of stereoisomeric products. At the beginning of a comprehensive study aimed at rationalizing the coordination behaviour of various benzoic acid derivatives towards a number of transition metals in dependence of the pH value of the reaction batches it seemed interesting to determine the crystal structure of the title compound to enable comparative studies. The crystal structure of unsubstituted benzoic acid (Bruno & Randaccio (1980); Wilson et al. (1996)) as well as the crystal structures of benzoic acid derivatives bearing a halogen atom in an ortho-position to the carboxylic acid group (Krausse & Dunken (1966); Ferguson & Sim (1961); Polito et al. (2008)) are apparent in the literature.

C–C–C angles within the phenyl ring span a range of 118 ° to 121 ° with the biggest as well as the smallest angle found on both C-atoms in the ortho-position to the C-atom bearing the carboxylic acid group. The latter one is found on the carbon atom bearing the trifluoromethyl group (Fig. 1).

The carboxylic acid group is slightly tilted with respect to the plane of the aromatic moiety. The least-squares planes defined by their respective atoms enclose an angle of 16.81 (26) °.

In the crystal structure, hydrogen bonds between the carboxylic acid groups of two molecules give rise to centrosymmetric dimers. These are further connected into double chains along [1 1/4 1] by C–H···O contacts whose range falls slightly below the sum of van-der-Waals radii of the corresponding atoms (Fig. 2). The latter contacts can be observed between the hydrogen atoms bonded to the carbon atoms in the ortho- as well as the meta-position to the carboxylic acid group and have the alcoholic as well as the carbonylic O-atom as acceptor. Additionally, the H-atom in the meta-position to the carboxylic acid group forms a contact to one of the fluorine atoms of the trifluoromethyl group. In terms of graph-set analysis (Etter et al. (1990); Bernstein et al. (1995).), the descriptor for the classical hydrogen bonds building the centrosymmetric dimers is R²₂(8) on the unitary level while the C–H···O-contacts necessitate a C¹₁(6)R²₂(10) descriptor on the same level. No π-stacking is obvious in the compound, however, a C–F···C_g interaction (F···C_g: 3.4803 (17) Å) can be observed.

The packing of the compound is shown in Figure 3.

Related literature top

For the crystal structure of benzoic acid using X-ray diffraction, see Bruno & Randaccio (1980). For the crystal structure of benzoic acid applying neutron radiation, see Wilson et al. (1996). For the crystal structure of ortho-fluorobenzoic acid, see Krausse & Dunken (1966). For the crystal structure of ortho-chlorobenzoic acid, see Ferguson & Sim (1961); Polito et al. (2008). For graph-set analysis of hydrogen bonds, see: Etter et al. (1990); Bernstein et al. (1995).

Experimental top

The compound was obtained commercially (fluorochem). Crystals suitable for the X-ray diffraction study were grown from an aqueous solution of the compound.

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 (Farrugia, 1997) and Mercury (Macrae et al., 2006); 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 [-1 0 0]. Hydrogen bonds are depicted with blue dashed lines, C–H···O contacts with yellow dashed lines and C–H···F contacts with red dashed lines. Symmetry operators: ⁱ x + 1, y, z + 1; ⁱⁱ -x + 3, -y, -z + 1; ⁱⁱⁱ -x + 2, -y, -z; ^iv x - 1, y, z - 1.
	Fig. 3. Molecular packing of the title compound, viewed along [-1 0 0] (anisotropic displacement ellipsoids drawn at 50% probability level).

2-(Trifluoromethyl)benzoic acid top

Crystal data top

C₈H₅F₃O₂	F(000) = 384
M_r = 190.12	D_x = 1.664 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 4165 reflections
a = 4.8816 (3) Å	θ = 2.7–28.3°
b = 20.6948 (14) Å	µ = 0.17 mm⁻¹
c = 7.9697 (5) Å	T = 200 K
β = 109.544 (4)°	Platelet, colourless
V = 758.74 (8) Å³	0.50 × 0.50 × 0.09 mm
Z = 4

Data collection top

Bruker APEXII CCD diffractometer	1548 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.048
Graphite monochromator	θ_max = 28.3°, θ_min = 3.4°
ϕ and ω scans	h = −6→6
7115 measured reflections	k = −27→27
1889 independent reflections	l = −10→10

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)] = 0.049	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.113	H-atom parameters constrained
S = 1.06	w = 1/[σ²(F_o²) + (0.0324P)² + 0.680P] where P = (F_o² + 2F_c²)/3
1889 reflections	(Δ/σ)_max < 0.001
119 parameters	Δρ_max = 0.30 e Å⁻³
0 restraints	Δρ_min = −0.33 e Å⁻³

Crystal data top

C₈H₅F₃O₂	V = 758.74 (8) Å³
M_r = 190.12	Z = 4
Monoclinic, P2₁/c	Mo Kα radiation
a = 4.8816 (3) Å	µ = 0.17 mm⁻¹
b = 20.6948 (14) Å	T = 200 K
c = 7.9697 (5) Å	0.50 × 0.50 × 0.09 mm
β = 109.544 (4)°

Data collection top

Bruker APEXII CCD diffractometer	1548 reflections with I > 2σ(I)
7115 measured reflections	R_int = 0.048
1889 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.049	0 restraints
wR(F²) = 0.113	H-atom parameters constrained
S = 1.06	Δρ_max = 0.30 e Å⁻³
1889 reflections	Δρ_min = −0.33 e Å⁻³
119 parameters

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

	x	y	z	U_iso*/U_eq
F1	0.8290 (3)	0.22541 (7)	0.5490 (2)	0.0602 (5)
F2	1.2257 (3)	0.17857 (6)	0.56593 (18)	0.0453 (3)
F3	0.9086 (3)	0.12968 (7)	0.65393 (16)	0.0455 (3)
O1	1.2631 (3)	0.01372 (7)	0.27504 (18)	0.0366 (3)
H1	1.4044	−0.0080	0.3397	0.055*
O2	1.2658 (3)	0.05058 (7)	0.53681 (17)	0.0368 (3)
C1	1.1610 (4)	0.04997 (8)	0.3755 (2)	0.0262 (4)
C2	0.9025 (4)	0.08893 (8)	0.2720 (2)	0.0252 (3)
C3	0.7956 (4)	0.14205 (8)	0.3418 (2)	0.0264 (4)
C4	0.5485 (4)	0.17387 (9)	0.2361 (3)	0.0324 (4)
H4	0.4766	0.2097	0.2833	0.039*
C5	0.4046 (5)	0.15424 (10)	0.0626 (3)	0.0366 (4)
H5	0.2336	0.1761	−0.0078	0.044*
C6	0.5102 (5)	0.10294 (11)	−0.0075 (3)	0.0381 (5)
H6	0.4137	0.0897	−0.1268	0.046*
C7	0.7571 (4)	0.07086 (10)	0.0963 (2)	0.0329 (4)
H7	0.8292	0.0357	0.0467	0.040*
C8	0.9405 (4)	0.16805 (9)	0.5273 (3)	0.0334 (4)

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
F1	0.0651 (10)	0.0483 (8)	0.0547 (8)	0.0222 (7)	0.0035 (7)	−0.0228 (7)
F2	0.0332 (7)	0.0462 (7)	0.0510 (7)	−0.0084 (5)	0.0069 (6)	−0.0134 (6)
F3	0.0422 (7)	0.0658 (9)	0.0285 (6)	0.0038 (6)	0.0119 (5)	−0.0006 (6)
O1	0.0363 (8)	0.0448 (8)	0.0270 (6)	0.0172 (6)	0.0084 (6)	−0.0008 (6)
O2	0.0342 (8)	0.0455 (8)	0.0255 (6)	0.0146 (6)	0.0034 (5)	−0.0036 (6)
C1	0.0231 (8)	0.0258 (8)	0.0293 (8)	0.0008 (6)	0.0083 (7)	−0.0006 (7)
C2	0.0227 (8)	0.0275 (8)	0.0254 (8)	0.0014 (6)	0.0081 (6)	0.0015 (7)
C3	0.0264 (9)	0.0269 (8)	0.0269 (8)	0.0000 (7)	0.0101 (7)	0.0009 (7)
C4	0.0331 (10)	0.0297 (9)	0.0352 (9)	0.0070 (7)	0.0126 (8)	0.0039 (8)
C5	0.0328 (10)	0.0389 (10)	0.0342 (10)	0.0091 (8)	0.0062 (8)	0.0081 (8)
C6	0.0358 (11)	0.0469 (11)	0.0266 (9)	0.0061 (9)	0.0036 (8)	−0.0002 (8)
C7	0.0331 (10)	0.0372 (10)	0.0270 (9)	0.0062 (8)	0.0080 (7)	−0.0023 (7)
C8	0.0300 (10)	0.0343 (10)	0.0341 (10)	0.0052 (8)	0.0084 (8)	−0.0065 (8)

Geometric parameters (Å, º) top

F1—C8	1.341 (2)	C3—C4	1.385 (3)
F2—C8	1.339 (2)	C3—C8	1.509 (3)
F3—C8	1.333 (2)	C4—C5	1.386 (3)
O1—C1	1.311 (2)	C4—H4	0.9500
O1—H1	0.8400	C5—C6	1.378 (3)
O2—C1	1.214 (2)	C5—H5	0.9500
C1—C2	1.492 (2)	C6—C7	1.382 (3)
C2—C7	1.393 (2)	C6—H6	0.9500
C2—C3	1.409 (2)	C7—H7	0.9500

C1—O1—H1	109.5	C6—C5—H5	120.1
O2—C1—O1	122.74 (16)	C4—C5—H5	120.1
O2—C1—C2	123.96 (16)	C5—C6—C7	119.81 (19)
O1—C1—C2	113.29 (15)	C5—C6—H6	120.1
C7—C2—C3	118.36 (16)	C7—C6—H6	120.1
C7—C2—C1	117.59 (16)	C6—C7—C2	121.46 (18)
C3—C2—C1	124.05 (16)	C6—C7—H7	119.3
C4—C3—C2	119.55 (17)	C2—C7—H7	119.3
C4—C3—C8	117.00 (16)	F3—C8—F2	107.39 (16)
C2—C3—C8	123.43 (16)	F3—C8—F1	105.94 (17)
C3—C4—C5	121.01 (18)	F2—C8—F1	105.20 (16)
C3—C4—H4	119.5	F3—C8—C3	113.20 (16)
C5—C4—H4	119.5	F2—C8—C3	113.19 (16)
C6—C5—C4	119.79 (18)	F1—C8—C3	111.35 (16)

O2—C1—C2—C7	−162.52 (18)	C4—C5—C6—C7	0.8 (3)
O1—C1—C2—C7	16.4 (2)	C5—C6—C7—C2	0.4 (3)
O2—C1—C2—C3	16.7 (3)	C3—C2—C7—C6	−1.3 (3)
O1—C1—C2—C3	−164.37 (17)	C1—C2—C7—C6	177.90 (19)
C7—C2—C3—C4	1.1 (3)	C4—C3—C8—F3	108.95 (19)
C1—C2—C3—C4	−178.06 (17)	C2—C3—C8—F3	−72.5 (2)
C7—C2—C3—C8	−177.38 (18)	C4—C3—C8—F2	−128.55 (19)
C1—C2—C3—C8	3.4 (3)	C2—C3—C8—F2	50.0 (2)
C2—C3—C4—C5	0.0 (3)	C4—C3—C8—F1	−10.3 (3)
C8—C3—C4—C5	178.62 (18)	C2—C3—C8—F1	168.25 (18)
C3—C4—C5—C6	−1.0 (3)

Hydrogen-bond geometry (Å, º) top

Cg is the centroid of the C2–C7 ring.

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2ⁱ	0.84	1.81	2.6459 (19)	173
C6—H6···O2ⁱⁱ	0.95	2.66	3.590 (3)	167
C6—H6···F3ⁱⁱ	0.95	2.63	3.303 (3)	128
C7—H7···O1ⁱⁱⁱ	0.95	2.66	3.411 (2)	137
C8—F1···Cg^iv	1.34 (1)	3.48 (1)	4.806 (2)	170 (1)

Symmetry codes: (i) −x+3, −y, −z+1; (ii) x−1, y, z−1; (iii) −x+2, −y, −z; (iv) x, −y−1/2, z−1/2.

Experimental details

Crystal data
Chemical formula	C₈H₅F₃O₂
M_r	190.12
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	200
a, b, c (Å)	4.8816 (3), 20.6948 (14), 7.9697 (5)
β (°)	109.544 (4)
V (Å³)	758.74 (8)
Z	4
Radiation type	Mo Kα
µ (mm⁻¹)	0.17
Crystal size (mm)	0.50 × 0.50 × 0.09

Data collection
Diffractometer	Bruker APEXII CCD diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	7115, 1889, 1548
R_int	0.048
(sin θ/λ)_max (Å⁻¹)	0.667

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.049, 0.113, 1.06
No. of reflections	1889
No. of parameters	119
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.30, −0.33

Computer programs: APEX2 (Bruker, 2010), SAINT (Bruker, 2010), SHELXS97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2006), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).

Hydrogen-bond geometry (Å, º) top

Cg is the centroid of the C2–C7 ring.

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1···O2ⁱ	0.84	1.81	2.6459 (19)	173.0
C6—H6···O2ⁱⁱ	0.95	2.66	3.590 (3)	167
C6—H6···F3ⁱⁱ	0.95	2.63	3.303 (3)	128
C7—H7···O1ⁱⁱⁱ	0.95	2.66	3.411 (2)	137
C8—F1···Cg^iv	1.341 (2)	3.4803 (17)	4.806 (2)	169.96 (13)

Symmetry codes: (i) −x+3, −y, −z+1; (ii) x−1, y, z−1; (iii) −x+2, −y, −z; (iv) x, −y−1/2, z−1/2.

Acknowledgements

The authors thank Mr Robert Bell for helpful discussions.

References

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ISSN: 2056-9890

Volume 67| Part 4| April 2011| Page o907

doi:10.1107/S1600536811009597

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