3-(2-Bromo-4,5-dimethoxyphenyl)propiononitrile

In the molecule of the title compound, C11H12BrNO2, a weak intramolecular C—H⋯Br hydrogen bond results in the formation of a five-membered ring, which adopts an envelope conformation with the H atom displaced by 0.486 Å from the plane of the other ring atoms. In the crystal structure, intermolecular C—H⋯O hydrogen bonds link the molecules.

In the molecule of the title compound, C 11 H 12 BrNO 2 , a weak intramolecular C-HÁ Á ÁBr hydrogen bond results in the formation of a five-membered ring, which adopts an envelope conformation with the H atom displaced by 0.486 Å from the plane of the other ring atoms. In the crystal structure, intermolecular C-HÁ Á ÁO hydrogen bonds link the molecules.
In the molecule of (I), (

Experimental
For the preparation of the title compound, beta-(2-bromo-4,5-dimethoxypenyl) -alpha-cyanoproponic acid (16 mmol) was dissolved in dimethylacetamide (10 ml), the mixture was heated at 443 K and evolution of the calculated amount of CO 2 ceased after 30 min. The mixture was poured into water and set aside overnight. Crystals were separated, collected and washed with water and hexane. Crystals of (I) suitable for X-ray analysis were obtained by slow evaporation of a methanol solution.

Refinement
H atoms were positioned geometrically, with C-H = 0.93, 0.97 and 0.96 Å for aromatic, methylene and methyl H, respectively, and constrained to ride on their parent atoms with U iso (H) = xU eq (C), where x = 1.5 for methyl H, and x = 1.2 for all other H atoms.

Data collection
Enraf-Nonius CAD-4 diffractometer R int = 0.047 Radiation source: fine-focus sealed tube θ max = 25.2º Monochromator: graphite θ min = 1.6º T = 294(2) K h = −21→21 ω/2θ scans k = −21→0 Absorption correction: ψ scan (North et al., 1968) l = 0→8  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 > 2sigma(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.