4-(Carboxymethoxy)anilinium bromide

In the title hydrobromide salt, C8H10NO3 +·Br−, the positive charge resides on the N atom and the carboxyl –CO2 end of the cation carries an H atom. In the crystal, N—H⋯Br, O—H⋯Br and N—H⋯O hydrogen bonds link the cations and anions, forming a ladder propagating along the a axis.

In the title hydrobromide salt, C 8 H 10 NO 3 + ÁBr À , the positive charge resides on the N atom and the carboxyl -CO 2 end of the cation carries an H atom. In the crystal, N-HÁ Á ÁBr, O-HÁ Á ÁBr and N-HÁ Á ÁO hydrogen bonds link the cations and anions, forming a ladder propagating along the a axis.

Comment
We are interested in the dielectric-ferroelectric materials. Recent studies have revealed that small molecular compounds which have one or more amidogens probably have this kind of character (Jain et al., 2008 ;Korfer & Fusee et al., 1988). Thus, we want to find aromatic compounds containing amidogens having dielectric-ferroelectric properties. As part of our ongoing studies, we report here the crystal structure of the title compound, The dielectric constant of 2-(4-aminophenoxy) acetic acid bromide compound as a function of temperature indicates that the permittivity is basically temperature-independent, below the melting point (478k-480k) of the compound, the dielectric constant(4.51-8.33) as a function of temperature also goes smoothly, and there is no dielectric anomaly observed, so this compound should be not a real ferroelectrics or there may be no distinct phase transition occurred within the measured temperature range.
The asymmetric unit of the title compound contains one 2-(4-aminophenoxy) acetic acid cation and one bromide anion( fig   1). The non-H atoms of the 2-(4-aminophenoxy) acetic acid are essentially coplanar. In the crystal structure, intermolecular N-H···Br hydrogen bonds link cations and anions to form one-dimensional ladder propagating wavily along the a axis direction (fig 2).
Experimental ethyl 2-(4-aminophenoxy)acetate (1.95 g) and methanol(30 ml) were added to a round-bottomed flask with a magnetic stirrer bar, then hydrogen chloride(36%) 1.02 g was added into the mixture. The mixture was stirred for 4 h at room temperature.
Colourless plate-like crystals of (I) were grown from an ethanol solution of the title compound by slow evaporation at room temperature.

Refinement
Positional parameters of all the H atoms bonded to C atom were calculated geometrically with C-H = 0.93 to 0.93 \%A, with Uĩso~(H) = 1.2U~eq~(Caromatic,). All other H atom were locatd in a difference Fourier map and refined freely.

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 Rfactors(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