3,4-Dimethylphenyl benzoate

In the title compound, C15H14O2, the terminal rings form a dihedral angle of 52.39 (4)°. The mean plane of the central ester group [r.m.s. deviation = 0.0488 Å] is twisted away from the benzene and phenyl rings by 60.10 (4) and 8.67 (9)°, respectively. In the crystal, molecules are linked by weak C—H⋯O hydrogen bonds, forming C(6) chains which run along [100].


Synthesis and crystallization
The reagents and solvents for the synthesis were obtained from Aldrich Chemical Co., and were used without additional purification. The title molecule was synthesized using equimolar quantities of 3,4-dimethylphenol and benzoyl chloride.
3,4-Dimethylphenol (0.50 g, 4.10 mmol) was added to a solution of anhydrous aluminum chloride (0.40 g, 3.00 mmol) in anhydrous dichloromethane (25 mL). The resulting solution was cooled and benzoyl chloride (0.57 g) was added slowly at 0-5°. After complete addition, the mixture was left under stirring at room temperature for 0.5 h, and then it was heated (reflux) to 50° C for 1 h. The reaction mixture was poured onto ice (100 g). The crude product was isolated by extraction with dichloromethane, and it was separated. The solution was dried over Na 2 SO 4 and it was evaporated at room temperature. The obtained amorphous product was dissolved in methanol and the solution was left to slow evaporation.
Colourless crystals of good quality were obtained with M.pt = 322 (1) K.

Refinement
All H-atoms were positioned at geometrically idealized positions with C-H distance of 0.95-0.98 Å, and with U iso (H) = 1.2-1.5U eq of the C-atoms to which they were bonded.

Results and discussion
In order to obtain more detailed information about the effect of substitution of the methyl groups on the structure of benzoate system, the structure determination of 3,4-dimethyl phenyl benzoate (I) has been carried out. Two very similar molecular structures, 2,3-dimethylphenyl benzoate, DMPB1 (Gowda et al., 2008a), and 2,4-dimethylphenyl benzoate, DMPB2 (Gowda et al., 2008b), were taken for comparison with the structure (I). The rings of (I), Fig. 1, form a dihedral angle of 52.39 (4)° while in DMPB1 and DMPB2 they form dihedral angles of 87.36 (6)° and 80.25 (5)°, respectively.
The other bond lengths and bond angles of DMPB1 and DMPB2 are close to the title system. The central ester moiety (C1-O7-C7(O8)-C8) is twisted away from the dimethyl-substituted benzeneand phenyl rings by 60.10 (4) and 8.67 (9)°, respectively. The crystal packing shows no classical hydrogen bonds and it is stabilized by weak C-H···O intermolecular hydrogen bonds, forming C(6) chains (Etter, 1990) along [100] (see Fig. 2). The C2 atom acts as hydrogen-bond donor to O1 atom at (x-1, +y, +z) (Nardelli, 1995); see Table 1.  Molecular conformation and atom numbering scheme for the title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are shown as spheres of arbitrary radius.

Figure 2
Part of the crystal structure of (I), showing the formation of chains which running along [100]. Symmetry code: (i) x-1, +y, +z. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.28 e Å −3 Δρ min = −0.24 e Å −3 Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.