3-Fluoro-4-methyl­benzoic acid

Batsanov, A.S.

doi:10.1107/S1600536804024389

organic compounds

CRYSTALLOGRAPHIC
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ISSN: 2056-9890

Volume 60| Part 11| November 2004| Pages o1948-o1949

https://doi.org/10.1107/S1600536804024389

3-Fluoro-4-methylbenzoic acid

Andrei S. Batsanov ^a ^*

^aDepartment of Chemistry, University of Durham, South Road, Durham DH1 3LE, England
^*Correspondence e-mail: a.s.batsanov@durham.ac.uk

(Received 22 September 2004; accepted 29 September 2004; online 9 October 2004)

The title compound, C₈H₇FO₂, shows a nearly planar molecular structure, with a dihedral angle between the benzene ring and the carboxyl group of 6.2 (1)°. Pairs of molecules are linked via O—H⋯O hydrogen bonding into dimers, which are located around centres of inversion.

Comment

The molecule of the title compound, (I), has been determined to provide a reference point for the study of ¹⁹F–¹³C–¹H coupling in NMR spectra of solids and liquid crystals (Antonioli, 2004 ). The molecule is nearly planar (Fig. 1 and Table 1). The dihedral angle between the benzene ring and the carboxyl group of 6.2 (1)° is somewhat larger than that in the parent 4-methylbenzoic (p-toluic) acid, (II), of 2.9° (Takwale & Pant, 1971 ). In the crystal structure of (I), pairs of molecules are linked into dimers by O—H⋯O hydrogen bonding, with an O⋯H distance of 1.70 (4) Å and an O⋯O distance of 2.612 (2) Å. The O—H⋯O angle of 176 (3)° indicates strong hydrogen bonding and the dimers are located around centres of inversion. Dimers are also found in (II) but the crystal packing is completely different from that in (I). In contrast to the structure determination of (II), in the present determination the carboxy H atom was located in a difference map.

Figure 1
The crystal structure of the title compound, showing a hydrogen-bonded dimer with labelling and displacement ellipsoids drawn at the 50% probability level. Hydrogen bonding is indicated by dashed lines. [Symmetry code: (i) −x, 2 − y, 1 − z.]

Experimental

Compound (I) was commercially available from Acros Organics (Loughborough, England). It was recrystallized from an aqueous solution.

Crystal data

C₈H₇FO₂
M_r = 154.14
Monoclinic, P2₁/c
a = 3.8132 (5) Å
b = 6.0226 (8) Å
c = 30.378 (4) Å
β = 92.50 (2)°
V = 696.98 (16) Å³
Z = 4
D_x = 1.469 Mg m⁻³
Mo Kα radiation
Cell parameters from 979 reflections
θ = 10.3–26.0°
μ = 0.12 mm⁻¹
T = 120 (2) K
Prism, colourless
0.55 × 0.19 × 0.16 mm

Data collection

SMART 6000 CCD area-detector diffractometer
ω scans
Absorption correction: none
9290 measured reflections
2036 independent reflections
1773 reflections with I > 2σ(I)
R_int = 0.067
θ_max = 30.0°
h = −5 → 5
k = −8 → 8
l = −42 → 42

Refinement

Refinement on F²
R[F² > 2σ(F²)] = 0.054
wR(F²) = 0.157
S = 1.12
2036 reflections
128 parameters
All H-atom parameters refined
w = 1/[σ²(F_o²) + (0.0713P)² + 0.4137P] where P = (F_o² + 2F_c²)/3
(Δ/σ)_max < 0.001
Δρ_max = 0.49 e Å⁻³
Δρ_min = −0.25 e Å⁻³

Table 1
Selected geometric parameters (Å, °)

F—C3	1.3595 (17)
O1—C7	1.3076 (18)
O2—C7	1.2354 (18)
C1—C6	1.389 (2)
C1—C2	1.395 (2)
C1—C7	1.481 (2)
C2—C3	1.379 (2)
C3—C4	1.389 (2)
C4—C5	1.396 (2)
C4—C8	1.505 (2)
C5—C6	1.393 (2)

C6—C1—C2	120.18 (13)
C3—C2—C1	117.86 (14)
F—C3—C2	117.88 (14)
F—C3—C4	117.96 (13)
C2—C3—C4	124.15 (14)
C3—C4—C5	116.56 (14)
C3—C4—C8	121.47 (14)
C5—C4—C8	121.97 (15)
C6—C5—C4	121.15 (14)
C1—C6—C5	120.10 (14)

Table 2
Hydrogen-bonding geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H01⋯O2ⁱ	0.92 (4)	1.70 (4)	2.6117 (17)	176 (3)
Symmetry code: (i) -x,2-y,1-z.

All H atoms were located in a difference map and were refined freely.

Data collection: SMART (Bruker, 2001 ); cell refinement: SMART; data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2001); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S1600536804024389/nc6002sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536804024389/nc6002Isup2.hkl

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SMART; data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 2001); software used to prepare material for publication: SHELXTL.

3-fluoro-4-methylbenzoic acid top

Crystal data top

C₈H₇FO₂	F(000) = 320
M_r = 154.14	D_x = 1.469 Mg m⁻³
Monoclinic, P2₁/c	Melting point = 442–444 K
Hall symbol: -P 2ybc	Mo Kα radiation, λ = 0.71073 Å
a = 3.8132 (5) Å	Cell parameters from 979 reflections
b = 6.0226 (8) Å	θ = 10.3–26.0°
c = 30.378 (4) Å	µ = 0.12 mm⁻¹
β = 92.50 (2)°	T = 120 K
V = 696.98 (16) Å³	Prism, colourless
Z = 4	0.55 × 0.19 × 0.16 mm

Data collection top

SMART 6000 CCD area-detector diffractometer	1773 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.067
Graphite monochromator	θ_max = 30.0°, θ_min = 1.3°
Detector resolution: 8 pixels mm^-1	h = −5→5
ω scans	k = −8→8
9290 measured reflections	l = −42→42
2036 independent reflections

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)] = 0.054	Hydrogen site location: difference Fourier map
wR(F²) = 0.157	All H-atom parameters refined
S = 1.12	w = 1/[σ²(F_o²) + (0.0713P)² + 0.4137P] where P = (F_o² + 2F_c²)/3
2036 reflections	(Δ/σ)_max < 0.001
128 parameters	Δρ_max = 0.49 e Å⁻³
0 restraints	Δρ_min = −0.25 e Å⁻³

Special details top

Experimental. The data collection nominally covered full sphere of reciprocal space, by a combination of 4 sets of ω scans; each set at different φ and/or 2θ angles and each scan (10 sec exposure) covering 0.3° in ω. Crystal to detector distance 4.85 cm.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement.

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

	x	y	z	U_iso*/U_eq
F	0.1213 (3)	0.71029 (19)	0.29337 (3)	0.0340 (3)
O1	0.2296 (4)	0.7513 (2)	0.48864 (4)	0.0310 (3)
H01	0.167 (9)	0.843 (6)	0.5110 (11)	0.069 (9)*
O2	−0.0547 (3)	0.9999 (2)	0.44542 (4)	0.0273 (3)
C1	0.2068 (4)	0.6875 (2)	0.41215 (5)	0.0194 (3)
C2	0.1227 (4)	0.7663 (3)	0.36981 (5)	0.0211 (3)
H2	−0.001 (6)	0.911 (4)	0.3651 (7)	0.028 (5)*
C3	0.2043 (4)	0.6340 (3)	0.33464 (5)	0.0227 (3)
C4	0.3647 (4)	0.4276 (3)	0.33872 (5)	0.0222 (3)
C5	0.4442 (4)	0.3533 (3)	0.38153 (5)	0.0232 (3)
H5	0.565 (6)	0.209 (4)	0.3840 (7)	0.026 (5)*
C6	0.3668 (4)	0.4818 (3)	0.41798 (5)	0.0220 (3)
H6	0.423 (6)	0.428 (4)	0.4486 (7)	0.030 (5)*
C7	0.1160 (4)	0.8265 (2)	0.45024 (5)	0.0206 (3)
C8	0.4497 (5)	0.2923 (3)	0.29891 (6)	0.0305 (4)
H81	0.597 (7)	0.368 (5)	0.2804 (9)	0.049 (7)*
H82	0.592 (8)	0.165 (5)	0.3067 (9)	0.052 (8)*
H83	0.247 (8)	0.252 (5)	0.2817 (10)	0.049 (7)*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
F	0.0460 (6)	0.0376 (6)	0.0181 (5)	0.0058 (5)	−0.0011 (4)	0.0025 (4)
O1	0.0440 (7)	0.0308 (6)	0.0179 (5)	0.0139 (5)	−0.0005 (5)	−0.0008 (4)
O2	0.0357 (6)	0.0240 (6)	0.0219 (5)	0.0085 (5)	0.0003 (4)	−0.0002 (4)
C1	0.0196 (6)	0.0198 (6)	0.0191 (6)	0.0008 (5)	0.0015 (5)	−0.0002 (5)
C2	0.0216 (6)	0.0207 (7)	0.0211 (7)	0.0017 (5)	0.0008 (5)	0.0007 (5)
C3	0.0240 (7)	0.0265 (7)	0.0176 (6)	−0.0024 (6)	0.0002 (5)	0.0007 (5)
C4	0.0177 (6)	0.0258 (7)	0.0231 (7)	−0.0013 (5)	0.0025 (5)	−0.0048 (5)
C5	0.0214 (6)	0.0216 (7)	0.0267 (7)	0.0023 (5)	0.0014 (5)	−0.0017 (5)
C6	0.0220 (6)	0.0222 (7)	0.0218 (7)	0.0018 (5)	0.0003 (5)	0.0002 (5)
C7	0.0223 (6)	0.0209 (7)	0.0186 (6)	0.0011 (5)	0.0013 (5)	0.0003 (5)
C8	0.0293 (8)	0.0356 (9)	0.0268 (8)	0.0023 (7)	0.0031 (6)	−0.0099 (7)

Geometric parameters (Å, º) top

F—C3	1.3595 (17)	C3—C4	1.389 (2)
O1—C7	1.3076 (18)	C4—C5	1.396 (2)
O1—H01	0.92 (4)	C4—C8	1.505 (2)
O2—C7	1.2354 (18)	C5—C6	1.393 (2)
C1—C6	1.389 (2)	C5—H5	0.98 (2)
C1—C2	1.395 (2)	C6—H6	1.00 (2)
C1—C7	1.481 (2)	C8—H81	0.93 (3)
C2—C3	1.379 (2)	C8—H82	0.96 (3)
C2—H2	1.00 (2)	C8—H83	0.95 (3)

C7—O1—H01	111 (2)	C6—C5—H5	123.0 (13)
C6—C1—C2	120.18 (13)	C4—C5—H5	115.8 (13)
C6—C1—C7	121.39 (13)	C1—C6—C5	120.10 (14)
C2—C1—C7	118.42 (13)	C1—C6—H6	118.9 (14)
C3—C2—C1	117.86 (14)	C5—C6—H6	121.0 (14)
C3—C2—H2	120.9 (13)	O2—C7—O1	123.44 (14)
C1—C2—H2	121.2 (13)	O2—C7—C1	121.65 (13)
F—C3—C2	117.88 (14)	O1—C7—C1	114.91 (13)
F—C3—C4	117.96 (13)	C4—C8—H81	112.2 (18)
C2—C3—C4	124.15 (14)	C4—C8—H82	111.8 (17)
C3—C4—C5	116.56 (14)	H81—C8—H82	101 (2)
C3—C4—C8	121.47 (14)	C4—C8—H83	112.7 (18)
C5—C4—C8	121.97 (15)	H81—C8—H83	107 (2)
C6—C5—C4	121.15 (14)	H82—C8—H83	112 (2)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
O1—H01···O2ⁱ	0.92 (4)	1.70 (4)	2.6117 (17)	176 (3)

Symmetry code: (i) −x, −y+2, −z+1.

References

Antonioli, G. C. (2004). PhD thesis, University of Durham, England. Google Scholar
Bruker (2001). SMART (Version 5.625), SAINT (Version 6.02A) and SHELXTL (Version 6.12). Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany. Google Scholar
Takwale, M. G. & Pant, L. M. (1971). Acta Cryst. B27, 1152–1158. CSD CrossRef CAS IUCr Journals Web of Science Google Scholar

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