(E)-4-(4-Fluoro­styr­yl)benzoic acid

Saba Nazir; Khushi Muhammad; M Khawar Rauf; Masahiro Ebihara; Shahid Hameed

doi:10.1107/S1600536808012920

. 2008 May 7;64(Pt 6):o1013. doi: 10.1107/S1600536808012920

(E)-4-(4-Fluorostyryl)benzoic acid

Saba Nazir ^a, Khushi Muhammad ^a, M Khawar Rauf ^b, Masahiro Ebihara ^b, Shahid Hameed ^a,^*

PMCID: PMC2961507 PMID: 21202538

Abstract

The title compound, C₁₅H₁₁FO₂, is an important intermediate in the synthesis of side-chain ligands for polymeric liquid crystals. The vinyl group is almost coplanar with both the aromatic rings. The crystal structure is stabilized by intermolecular O—H⋯O hydrogen bonding.

Related literature

For related literature, see: Ahmad et al. (2003 ▶); Collings & Hird (1997 ▶); Frazee & Foraker (2008 ▶); Hameed & Rama (2004 ▶); Hussain et al. (2005 ▶); Nazir et al. (2008 ▶); Ribeiro et al. (2008 ▶); Wang et al. (2008 ▶); Higashi (1999 ▶); Yasuda et al. (2000 ▶).

Experimental

Crystal data

C₁₅H₁₁FO₂
M _r = 242.24
Monoclinic,
a = 6.261 (4) Å
b = 23.096 (15) Å
c = 8.269 (5) Å
β = 107.072 (8)°
V = 1143.1 (13) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 123 (2) K
0.45 × 0.30 × 0.18 mm

Data collection

Rigaku/MSC Mercury CCD diffractometer
Absorption correction: none
9111 measured reflections
2589 independent reflections
2399 reflections with I > 2σ(I)
R _int = 0.036

Refinement

R[F ² > 2σ(F ²)] = 0.065
wR(F ²) = 0.155
S = 1.16
2589 reflections
167 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.55 e Å⁻³
Δρ_min = −0.28 e Å⁻³

Data collection: CrystalClear (MSC/Rigaku, 2001 ▶); cell refinement: CrystalClear; data reduction: TEXSAN (MSC/Rigaku, 2004 ▶); program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPII (Johnson, 1976 ▶); software used to prepare material for publication: SHELXL97 and TEXSAN.

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808012920/hg2398sup1.cif

e-64-o1013-sup1.cif^{(16.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808012920/hg2398Isup2.hkl

e-64-o1013-Isup2.hkl^{(127.2KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O2—H2⋯O1ⁱ	1.04 (4)	1.57 (4)	2.610 (2)	174 (3)

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Symmetry code: (i) Inline graphic .

Acknowledgments

MKR is grateful to the Higher Education Commission of Pakistan for financial support under the International Support Initiative for Doctoral Fellowships at Gifu University, Japan.

supplementary crystallographic information

Comment

Carboxylic acids constitute an important class of organic compounds and have been used by the medicinal industry as important drugs (Ribeiro et al., 2008; Frazee & Foraker 2008; Hameed & Rama 2004). The carboxylic acids have also found applications as intermediates in the synthesis of an enormous number of organic compounds, in general (Hussain et al., 2005; Ahmad et al., 2003), and in the synthesis of side chain ligands for polymeric liquid crystals, in particular (Wang et al., 2008; Nazir et al., 2008). The liquid crystalline molecules containing substituents at 4-position behave as well ordered calamitic ligands as a side chain group (Collings & Hird, 1997) in side chain polymeric liquid crysrtals (SCPLCs). The derivatives of 4-(4-substituted styryl)benzoic acids have found applications as side chain groups in SCPLCs (Wang et al., 2008). As a part of a project to synthesize ligands for SCPLCs, the title compound, (E)-4-(4-fluorostyryl)benzoic acid (I), was synthesized by reacting 4-fluorobenzaldehyde with methyl [4-(methoxycarbonyl)benzyl]triphenylphosphonium bromide (Nazir et al., 2008) followed by hydrolysis. In the present article, the crystal structure of (I) is being reported. Bond lengths and angles are within the normal ranges as given for vinylbenzoic acid (Yasuda et al., 2000). The C(1)—O(1) and C(1)—O(2) bond lengths are 1.252 (2) and 1.291 (2) respectively,clearly indicating the partial double bond character of the carboxylate group. The carboxylic acid group subtends a dihedral angle[13.72 (16)°] with the phenyl ring C(2)/C(3)/C(4)/C(5)/C(6)/C(7).The vinyl group is almost coplanar with both the phenyl rings. The torsion angles between the phenyl rings and vinyl group fulfill the condition of coplanarity[near to 0° or 180 °]. Two molecules related by an inversion center form a dimer via two hydrogen bonds composed of two carboxyl groups as shown in Fig. 2.

Experimental

Methyl 4-(4-fluorostyryl)benzoate 0.8g (0.0031moles) and sodium hydroxide 0.126g (0.0031 moles) were dissolved in a mixture of 10 ml of methanol and 30 ml of water, and the mixture refluxed for 3 hours. The reaction mixture was cooled to room temperature and acidified with 6M HCl. The precipitated solid was filtered and recrystallized from hot ethanol. Yield: 76%, m.p: 240-252°C, R_f = 0.22 (n-hexane : ethyl acetate 7 : 3). IR (ν_max, KBr, cm^-1): 3300-2500, 1715, 1620, 1600, 1580, 1188, 1119, 965,834. ¹H-NMR (300 MHz,DMSO-d₆): δ 7.25 (2H, d, J = 9.0 Hz),7.28 (1H, d, J= 16.2 Hz), 7.42 (1H, d, J = 16.2 Hz), 7.71-7.67 (4H, m),7.95 (2H, d, J = 8.1 Hz), 12.93 (1H, s). ¹³C-NMR (75 MHz, DMSO-d₆): δ 116.16 (d, J= 23 Hz), 126.90, 127.77, 129.23, 130.08 (d, J = 8 Hz), 131.95, 132.49, 133.71 (d, J = 3 Hz), 141.83, 162.42 (d, J = 246 Hz), 167.54.