2-(2-Methyl­benzo­yl)benzoic acid: catemeric hydrogen bonding in a γ-keto acid

Natalia A Platosz; Roger A Lalancette; Hugh W Thompson; Jacob M Newman; Ari Schachter

doi:10.1107/S1600536813025099

. 2013 Sep 18;69(Pt 10):o1547–o1548. doi: 10.1107/S1600536813025099

2-(2-Methylbenzoyl)benzoic acid: catemeric hydrogen bonding in a γ-keto acid¹

Natalia A Platosz ^a, Roger A Lalancette ^a,^*, Hugh W Thompson ^a, Jacob M Newman ^b, Ari Schachter ^b

PMCID: PMC3790413 PMID: 24098232

Abstract

The crystal structure of the title compound, C₁₅H₁₂O₃, displays catemeric aggregation involving O—H⋯O hydrogen bonds progressing from the carboxyl group of one molecule to the ketone O atom of another glide-related neighbor. The molecule is twisted, with the toluene 80.61 (3)° out of plane with respect to the phenyl group of the benzoic acid. The acid group makes a dihedral angle of 13.79 (14)° with the attached phenyl ring. The molecules are achiral, but the space group glide planes create alternating conformational chirality in the chain units. The four hydrogen-bonding chains progress along [001] in an A—A—B—B pattern (right-to-left versus left-to-right), and are related to each other by the center of symmetry at (0.5, 0.5, 0.5) in the chosen cell. There is one close contact (2.54 Å) between a phenyl H atom and the acid carbonyl from a symmetry-related molecule.

Related literature

For a discussion of highly ordered carboxyl bond distances and angles, see: Borthwick (1980 ▶). For close contact information, see: Steiner (1997 ▶). For related structures, see: Abell et al. (1991 ▶); Barcon et al. (1998 ▶, 2002 ▶); Degen & Bolte (1999 ▶); Hickmott et al. (1985 ▶); Kashyap et al. (1995 ▶); Song et al. (2008 ▶); Thompson et al. (1998 ▶); Watson et al. (1990 ▶). For preparation of the title compound, see: Newman & McCleary (1941 ▶). For a description of the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

C₁₅H₁₂O₃
M _r = 240.25
Orthorhombic,
a = 10.7450 (2) Å
b = 10.1737 (2) Å
c = 21.6588 (4) Å
V = 2367.66 (8) Å³
Z = 8
Cu Kα radiation
μ = 0.77 mm⁻¹
T = 100 K
0.45 × 0.26 × 0.20 mm

Data collection

Bruker SMART CCD APEXII area-detector diffractometer
Absorption correction: numerical (SADABS; Sheldrick, 2008a ▶) T _min = 0.724, T _max = 0.862
20799 measured reflections
2143 independent reflections
2075 reflections with I > 2σ(I)
R _int = 0.024

Refinement

R[F ² > 2σ(F ²)] = 0.030
wR(F ²) = 0.076
S = 1.07
2143 reflections
169 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.24 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: APEX2 (Bruker, 2006 ▶); cell refinement: SAINT (Bruker, 2005 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008b ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablock(s) I, global. DOI: 10.1107/S1600536813025099/bg2513sup1.cif

e-69-o1547-sup1.cif^{(17.6KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813025099/bg2513Isup2.hkl

e-69-o1547-Isup2.hkl^{(105.5KB, hkl)}

Click here for additional data file.^{(4.7KB, cml)}

Supplementary material file. DOI: 10.1107/S1600536813025099/bg2513Isup3.cml

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
O3—H3A⋯O1ⁱⁱ	0.932 (18)	1.714 (18)	2.6477 (11)	172.3 (16)

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Symmetry code: (ii) Inline graphic .

Acknowledgments

The authors acknowledge support by NSF–CRIF grant No. 0443538.

supplementary crystallographic information

1. Comment

This carboxyl-to-ketone catemer (I) is an achiral molecule which generates heterochiral chains due to the glide-related chain members. Normally, these types of catemers involve homochiral chains having either a screw or translational internal relationship (Hickmott et al., 1985; Abell et al., 1991; Kashyap et al., 1995). Rarer are heterochiral chains resulting from glide-plane symmetry, which is the case here (Watson et al., 1990; Barcon et al., 1998, 2002; Thompson et al., 1998).

Fig. 1 shows the asymmetric unit for (I) with its numbering. The molecule has many options for rotation, allowing for the angle between the toluene ring and the phenyl ring of the benzoic acid to be nearly perpendicular at 80.61 (3)°. The acid group [C7—O2—O3] makes a dihedral angle with the phenyl group [C1—C6] = 13.79 (14)°, and the ketone [O1—C8—C2—C9] has a dihedral angle to the phenyl group [C1—C6] = 78.99 (3)°. The acid group [C7—O2—O3] makes a dihedral angle of 74.84 (8)° with the plane of the ketone [O1—C8—C2—C9], and also an angle of 76.65 (7)° with the plane of the toluene ring [C9—C14]. There is one close contact (2.54 Å) between a phenyl H atom (H12) and the acid carbonyl (O2) from a symmetry-related molecule (Steiner, 1997).

The structures of 2-(4-methylbenzoyl)benzoic acid and its hydrate have been published: HOFGAK (Degen & Bolte, 1999) is the p-toluene analog of (I) and MIXTOD (Song, et al., 2008) is the hydrated p-toluene analog [Cambridge Structural Database (CSD, Version 5.28, update of Nov., 2006; Allen, 2002)]. Both of these molecules crystallize as centrosymmetric dimers of the acid groups (Borthwick, 1980), but the hydrated version has two water molecules inserted between the acid dimers. In HOFGAK, the dihedral angle between the toluene and the benzoic acid = 89.8°, and the acid is coplanar [0.00°] with the phenyl ring. In MIXTOD, these same angles are 69.5 and 25.8°, respectively. In (I), the toluene and the ketone are essentially coplanar [dihedral angle = 1.91 (7)°], but in HOFGAK and MIXTOD, this same angle is 20.6 and 10.8°, respectively.

Figures 2a and 2b are partial packing diagrams showing the H bonds progressing catemerically between glide-related molecules; the individual members making up each chain have alternating chirality. The handedness of the molecules is differentiated by patterning of the bonds.

Centrosymmetrically-related H-bonded chains can be seen by comparing the A molecule in Fig. 2a with the D molecule in Fig. 2b; the B and C molecules are also centrosymmetrically related.

We characterize the geometry of H bonding to carbonyls using a combination of H···O=C angle and H···O=C—C torsion angle. These describe the approach of the acid H atom to the carbonyl O in terms of its deviation from, respectively, C=O axiality (ideal = 120°) and planarity with the carbonyl (ideal = 0°). In (I), the values for these two angles are 116.5 (5) and 10.0 (6)°.

2. Experimental

1.20 g of Mg and 1 ml of 1-bromo-2-methylbenzene were added to 17 ml of dry diethyl ether, followed by the gradual addition of 4.625 ml of 1-bromo-2-methylbenzene. The resulting Grignard reagent was added over a period of 30 min to a stirred suspension of 6.2 g of phthalic anhydride in 35 ml of dry benzene and 15 ml of dry diethyl ether. The pale orange mixture was stirred for 30 minutes, refluxed for 10 minutes, allowed to stir overnight and refluxed for a further 10 minutes. 7 ml of HCl was added along with a small quantity of ice water. The resulting solution was distilled to dryness. The glassy product was then dissolved in aqueous KOH and filtered through Celite. The filtrate was then acidified with HCl and extracted with ether into several fractions. The fractions not yielding crystals melting between 100–110°C were discarded, and the remaining fractions were combined. These were then passed through an alumina column and the solvent allowed to concentrate, yielding pale yellow crystals. These were then recrystallized from 8.6 ml of methanol and 5 mL of water. The resulting fine needle-like crystals were then recrystallized again from pure ethanol at room temperature, yielding colourless block crystals. (See Newman & McCleary, 1941).