N-[2-(2-Chlorophenyl)-2-hydroxyethyl]propan-2-aminium hemioxalate

The asymmetric unit of the title compound, C11H17ClNO+·0.5C2O4 2−, consists of one N-[2-(2-chlorophenyl)-2-hydroxyethyl]propan-2-ammonium cation and one-half of a centrosymmetric oxalate anion. In the cation, the C/C/N plane of the ethylammonium group is almost perpendicular to the benzene ring, with a dihedral angle of 88.72 (17)°. In the crystal structure, the two components are connected by O—H⋯O and N—H⋯O hydrogen bonds, forming a supramolecular tape along the a axis. Between the tapes, a C—H⋯O interaction is observed.

The asymmetric unit of the title compound, C 11 H 17 ClNO + Á-0.5C 2 O 4 2À , consists of one N-[2-(2-chlorophenyl)-2-hydroxyethyl]propan-2-ammonium cation and one-half of a centrosymmetric oxalate anion. In the cation, the C/C/N plane of the ethylammonium group is almost perpendicular to the benzene ring, with a dihedral angle of 88.72 (17) . In the crystal structure, the two components are connected by O-HÁ Á ÁO and N-HÁ Á ÁO hydrogen bonds, forming a supramolecular tape along the a axis. Between the tapes, a C-HÁ Á ÁO interaction is observed.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: IS2425).

Comment
Many crystalline compounds of oxalic acid has been studied previously (Marsau et al., 1979;Martin & Pinkerton, 1998;Czugler et al., 2007). To test the capability of oxalic acid we have synthesized the title compound, (I), containing oxalic acid and clorprenaline (Tang et al., 2009) which is one of a series of structurally related β-adrenoceptorblocking drugs.
Association of one clorprenaline and half of oxalic acid acid molecule leads to the title compound ( Fig. 1). Compared with previous studies, in (I), there are no unusual bond distances or angles. In the molecule of clorprenaline the Cl atom and the phenyl plane is almost planar with the deviation of 0.0115 Å.The dihedral angle between the plane formed by C1/C2/C8 and the benzene plane is 88.4°, which shows that the two planes are almost perpendicular.
O-H···O and N-H···O hydrogen bonds are found in the cystal structure and are essential forces in crystal formation.

Experimental
Racemic clorprenaline was prepared by clorprenaline hydrochloride purchased from ShangHai Shengxin Medicine & Chemical Co., Ltd. ShangHai, China. Clorprenaline hydrochloride and NaOH in a molar ratio of 1:1 were mixed and dissolved in a methanol-water solution (1:1 v/v). The precipitate formed was filtered off, washed with water and dried. It was used without further purification. Racemic Clorprenaline (0.5 g, 0.0023 mol) was dissolved in ethanol (20 ml) and oxalic acid (0.21, 0.0023 mol) was dissolved in water (10 ml). The mixture was dissovled by heating to 353 K where a clear solution resulted. The resulting solution was concentrated and colorless block-shaped crystals of (I) were obtained within two weeks at room temperature.  Refinement. Refinement using reflections with F 2 > 2.0 σ(F 2 ). The weighted R-factor(wR), goodness of fit (S) and R-factor (gt) are based on F, with F set to zero for negative F. The threshold expression of F 2 > 2.0 σ(F 2 ) is used only for calculating R-factor (gt).