Methyl (2Z)-2-bromomethyl-3-(2,4-dichlorophenyl)prop-2-enoate

In the title compound C11H9BrCl2O2, which represents the Z isomer, the methylacrylate moiety is essentially planar within 0.039 (2) Å and has an extended trans configuration. The benzene ring makes a dihedral angle of 28.3 (1)° with the mean plane of the methylacrylate moiety. The crystal packing is characterized by C—H⋯O hydrogen bonding and halogen–halogen interactions [Cl⋯Cl = 3.486 (3) Å], resulting in the formation of R 2 2(11) ring motifs and connecting the molecules into chains propagating along the b axis.

In the title compound C 11 H 9 BrCl 2 O 2 , which represents the Z isomer, the methylacrylate moiety is essentially planar within 0.039 (2) Å and has an extended trans configuration. The benzene ring makes a dihedral angle of 28.3 (1) with the mean plane of the methylacrylate moiety. The crystal packing is characterized by C-HÁ Á ÁO hydrogen bonding and halogen-halogen interactions [ClÁ Á ÁCl = 3.486 (3) Å ], resulting in the formation of R 2 2 (11) ring motifs and connecting the molecules into chains propagating along the b axis.
X-ray analysis established the molecular structure and atom connectivity of the title compound, as illustrated in Fig The crystal packing is stabilized by intermolecular C2-H2···O1 i hydrogen bond and halogen interation of type I mode represented by Cl1···Cl2 i contact [d = 3.486 (3) Å, θ = 151.68 (6) °] which form R 2 2 (11) ring motifs which in turn, connect the molecules to form bands parallel to [0 1 0] (Schmidt et al. 2011, Johnson & Lemmerer, 2012. The symmetry code: (i) x,-1 + y,z. The packing view of the title compound is shown in Fig.2.

Experimental
To a stirred solution of methyl 2-((2,4-dichlorophenyl)(hydroxy)methyl) acrylate (4 mmol) in CH 2 Cl 2 (15 ml), 48% aqueous HBr (0.68 ml) was added at room temperature. The reaction mixture was cooled to 273 K and then catalytic amount of concentrated H 2 SO 4 was added dropwise. The reaction mixture was stirred well at room temperature for about 24 hrs. After the completion of the reaction (confirmed by TLC analysis), the reaction mixture was poured into water and the aqueous layer was extracted with ethyl acetate (3 x 10 ml). The combined organic layer was washed with brine (10 ml) and concentrated. The crude product thus obtained was purified by column chromatography (EtOAc/Hexane, 2-6%)

Refinement
Hydrogen atoms were placed in calculated positions with C-H = 0.93 -0.97 Å and refined in riding model with fixed isotropic displacement parameters: U iso (H) = 1.2 U eq (C) for aromatic and methylene groups U iso (H) = 1.5 U eq (O) for methyl group. The rotation angles for methyl group were optimized by least squares.

Figure 1
The molecular structure of the title compound with the atom numbering scheme. The displacement ellipsoids are drawn at 30% probability level. H atoms are presented as small spheres of arbitary radius.

Figure 2
Crystal structure of the title compound, showing the formation of R 2 2 (11) ring motifs. Hydrogen bonds are shown as dotted lines. The hydrogen atoms not involved in bonding have been omitted for the sake of clarity. where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max = 0.005 Δρ max = 0.59 e Å −3 Δρ min = −0.29 e Å −3

Special details
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 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 C1 0.2787 (