3-Chloro-N-(4-hydroxy-3-methoxybenzyl)-2,2-dimethylpropanamide

In the molecular structure of the title compound, C13H18ClNO3, the amide group is nearly perpendicular to the benzene ring, making a dihedral angle of 85.66 (9)°. The C=O bond distance of 1.242 (3) Å and the C—N bond distance of 1.333 (3) Å suggest electron delocalization in the amide fragment. Intermolecular O—H⋯O and N—H⋯O hydrogen bonding helps to stabilize the crystal structure.

The molecular structure of the title compound is shown in Fig. 1. The amide fragment is nearly perpendicular to the benzene ring [dihedral angle 85.66 (9))°]. The longer C9═O3 bond distance of 1.242 (3) Å and the shorter C9-N1 bond distance of 1.333 (3) Å suggest the electron delocalization in the amide fragment, which is comparable to that found in the related compound N-(4-Hydroxy-3-methoxybenzyl)benzamide (Xia et al. 2009).
Intermolecular O-H···O and N-H···O hydrogen bonding is present in the crystal structure (Table 1), which helps to stabilize the crystal structure.
Experimental 4-Hydroxy-3-methoxy benzylamine HCl salt (4.7 g, 25 mmol) and dimethylformamide (25 ml) were added to a 100 ml 3-necked flask equipped with an additional funnel, a thermometer and a magnetic stirrer. Water solution (10 ml) of NaOH (2.0 g) was added at room temperature. The mixture was stirred at 308 K for 30 min and then cooled to 273 K. An ether solution (10 ml) of 2,2-dimethyl-3-chloropropionyl chloride (3.9 g, 25 mmol) was added dropwise at about 273 K over 15 min. After stirred for 2 h at room temperature the mixture was poured into 1M HCl solution (120 ml) , and then extracted with ethyl acetate. The ethyl acetate extract was washed with saturated NaHCO 3 and brine. The extract was then dried over anhydrous Na 2 SO 4 and filtered. Solvents were removed under vacuum at about 308 K to give a solid crude. Recrystallization was performed twice with an absolute ethyl acetate to obtain colourless single crystals of the title compound.

Refinement
Hydroxy and imino H atoms were located in a difference Fourier map and were refined as riding in as-found relative positions with U iso (H) = 1.5U eq (N,O). Methyl H atoms were placed in calculated positions with C-H = 0.96 Å and torsion angle was refined to fit the electron density, U iso (H) = 1.5U eq (C). Other H atoms were placed in calculated positions with C-H = 0.93 (aromatic) and 0.97 Å (methylene), and refined in riding mode with U iso (H) = 1.2U eq (C).
supplementary materials sup-2 Figures Fig. 1. The molecular structure of the title compound with 30% probability displacement (arbitrary spheres for H atoms).

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