4-(Decyloxy)phenyl 2-oxo-7-trifluoromethyl-2H-chromene-3-carboxylate

The title compound, C27H29F3O5, is a liquid crystal (LC) and exhibits enantiotropic SmA phase transitions. In the crystal, the dihedral angle between the 2H-chromene ring system and the benzene ring is 62.97 (2)°. The three F atoms of the –CF3 group are disordered over two sets of sites with occupancy factors 0.71 (4):0.29 (4). In the crystal, pairs of C—H⋯O hydrogen bonds form inversion dimers and generate R 2 2(10) rings. The structure also features C—H⋯F and C—H⋯π interactions along [100] and [010], respectively.


Experimental
A mixture of 7-(trifluoromethyl)-2-oxo-2H-chromene-3-carboxylic acid (0.100 g, 0.1 mmol), 4-(decyloxy) phenol (0.100 g, 0.1 mmol) dicyclohexylcarbodiimide (DCC) (0.100 g, 0.1 mmol) and catalytic quantity of DMAP (N,N-dimethyl amino pyridine) were stirred at room temperature for 48hrs in dry dichloromethane. Progress of the reaction was monitored by TLC (ethyl acetate: pet ether 2:8). After the completion of the reaction, the reaction mass was diluted with water and extracted into dichloromethane (25 ml). The organic layer was washed with water and dried over anhydrous sodium sulfate. The crude product thus obtained was purified by column chromatography using ethyl acetate: petroleum ether (2:8) as eluent followed by recrystallization from ethanol. A single crystal suitable for X-ray diffraction was grown from ethanol.

Refinement
The H atoms bound to carbon were positioned with idealized geometry using a riding model with d(C-H) = 0.93-0.99 Å.
All C-H atoms were refined with isotropic displacement parameters set to 1.2-1.5 U eq (C). The F1, F2, and F3 fluorine atoms of the -CF 3 group were disordered over two sites and refined with site occupancy factors 0.71 (4):0.29 (4). The crystals were not of high quality which accounts for the high uncertainties in the lengths of the unit cell axes and the supplementary materials relatively high residuals.

Figure 1
Molecular structure of the title compound, showing displacement ellipsoids drawn at the 50% probability level. Only the major component of the disordered CF 3 group is shown.

Figure 2
Crystal packing of the title compound with hydrogen bonds drawn as dashed lines.

Figure 3
Packing of the title compound. C-H···π interactions are shown as dashed lines. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (