N-[2-(4-Bromobenzoyl)ethyl]isopropylaminium chloride

The crystal structure of the title compound, C12H17BrNO+·Cl−, is stabilized by N—H⋯Cl and C—H⋯O hydrogen bonds, forming a three-dimensional network. The interactions framework is completed by C—H⋯π contacts between a methylene group and the benzene ring of a symmetry-related molecule.


Comment
Mannich bases are generally formed by the reaction between formaldehyde, a secondary amine and a compound containing reactive hydrogen atoms. On occasion, aldehydes other than formaldehyde may be employed and the secondary amine may be replaced by ammonia and primary amines. This process is known as the Mannich reaction (Dimmock & Kumar, 1997).
A Mannich base having at least one hydrogen atom at the β position of amine group can undergo a deamination process to generate an α,β-unsaturated ketone moiety.
In the molecule of the tile compound ( Fig. 1), the bond lengths are within normal ranges (Allen et al., 1987), as well as bond angles.
In the crystal structure, molecules are linked via intermolecular N-H···Cl and C-H···O hydrogen bonds (Table 1, Fig. 2), forming a three dimensional network. Furthermore, a C-H···π interaction (Table 1) contributes to the stabilization of the crystal packing.

Experimental
A mixture of the appropriate ketone (50 mmol), para-formaldehyde (50 mmol), and iso-propylamine hydrochloride (27 mmol) was heated in an oil bath at 403 K. The reaction vessel was then removed from the oil bath and when the temperature of the mixture dropped to 338 K, ethyl acetate (40-80 ml) was added. The mixture was stirred at room temperature for 24 h. and the resulting precipitates were then collected and the Mannich base (I) was passed through a column of silica gel 60 (70-230 mesh) using methanol as eluent. After evaporation of the solvent, the product was recrystallized from methanol.  H 5.59, N 4.57. Found: C 46.74, H 5.52, N 4.59 (Mete et al., 2011).

Refinement
The H atoms of the NH 2 group, HN1 and HN2, were located in a difference map and refined with a distance restraint of N-H = 0.86 (1) Å. Their displacement parameters were calculated as U iso = 1.2U eq (N1). The other H atoms were positioned supplementary materials sup-2 geometrically with C-H = 0.93 (aromatic), 0.96 (methyl), 0.97 (methylene) and 0.98 Å (methine), and constrained to ride on their parent atoms with U iso (H) = 1.2U eq (C) or U iso (H) = 1.5U eq (methyl C). Fig. 1. The title compound with displacement ellipsoids for non-H atoms shown at the 30% probability level.