2-(4-Methoxyphenyl)-2-oxoethanaminium chloride

In the cation of the title compound, C9H12NO2 +·Cl−, the dihedral angle between the 2-oxoethanaminium N—C—C(=O)– plane [maximum deviation = 0.0148 (12) Å] and the benzene ring is 7.98 (8)°. The methoxy group is approximately in-plane with the benzene ring, with a C—O—C—C torsion angle of −2.91 (18)°. In the crystal, the cations and chloride anions are connected by N—H⋯Cl and C—H⋯Cl hydrogen bonds, forming a layer parallel to the bc plane. A C—H⋯π interaction further links the layers.

In the cation of the title compound, C 9 H 12 NO 2 + ÁCl À , the dihedral angle between the 2-oxoethanaminium N-C-C( O)-plane [maximum deviation = 0.0148 (12) Å ] and the benzene ring is 7.98 (8) . The methoxy group is approximately in-plane with the benzene ring, with a C-O-C-C torsion angle of À2.91 (18) . In the crystal, the cations and chloride anions are connected by N-HÁ Á ÁCl and C-HÁ Á ÁCl hydrogen bonds, forming a layer parallel to the bc plane. A C-HÁ Á Á interaction further links the layers.

Comment
The synthesis of nitrogen-containing heterocycles has long been a topic of intense research (Alvarez-Builla et al., 2011;Katritzky et al., 2010). This is due, in large part, to the importance of these compounds as drug candidates. The vast majority of new molecular entities (NMEs) contain at least one nitrogen atom in the chemical structure. A subcategory of these compounds are imidazoles, which are notable pharmacophores in a number of areas of discovery chemistry research (Chen et al., 2011). Appropriately, numerous synthetic approaches to these compounds have been published in the literature (Alvarez-Builla et al., 2011). Phenacyl amines are the key intermediate in the synthesis of various ketoamides and also provides a robust synthetic route toward 1H-4-substituted imidazole developed using phenacyl amines.
The asymmetric unit of the title compound as shown in Fig. 1 consists of one 2-(4-methoxyphenyl)-2-oxoethanaminium cation and one chloride anion. One proton is transferred from the hydrochloric acid to the N atom. The ketone side chain and the methoxy group are coplanar with the benzene ring (C2-C7) with the torsion angles of C6-C5-C8-C9 = 173.82 (11)° and C1-O1-C2-C7 = -2.91 (18)°, respectively. The bond lengths and angles are similar to a related structure (Zhang et al., 2009).
The crystal structure (Fig. 2) is mainly stabilized by N-H···Cl and C-H···Cl hydrogen bonds (Table 1). In the crystal structure, the amine N atom acts as donor whereas the chloride anion acts as acceptor, linking them into a layer parallel to the bc plane. A C-H···π interaction (Table 1), involving the benzene ring, further consolidates the crystal structure.

Experimental
A 40 ml ethanolic solution of 5 mmol 4-methoxy phenacyl bromide was stirred with 5 mmol of HMTA for 10 h. The solid precipitated was filtered and the precipitate was dissolved in HCl and evaporated to dryness to get the crystals. M.p.: 433 K.

Refinement
N-bound H atoms were located in a difference Fourier map and were refined freely [N-H = 0.95 (2) to 0.98 (2) Å]. The remaining H atoms were positioned geometrically (C-H = 0.95 to 0.99 Å) and refined with a riding model with U iso (H) = 1.2 or 1.5 U eq (C). A rotating group model was applied to the methyl group. In the final refinement, one outliner, 1 0 0, was omitted.

Figure 2
The crystal packing of the title compound, viewed along the a axis, showing the layer parallel to the bc plane. H atoms not involved in the intermolecular interactions (dashed lines) have been omitted for clarity.  (Cosier & Glazer, 1986) operating at 100.0 (1) K. 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.