N-(2-Chloroacetyl)glycine

The title compound, C4H6ClNO3, crystallizes with two independent molecules (A and B) in the asymmetric unit. In each molecule, there are N—H⋯O and N—H⋯Cl hydrogen bonds. Both molecules are relatively planar, with the mean plane of the acetamide [N—C(=O)C] group being inclined to the mean plane of the acetate group [C—C(=O)O] by 9.23 (13)° in molecule A and 6.23 (12)° in molecule B. In the crystal, adjacent molecules are linked by O—H⋯O hydrogen bonds and weak C—H⋯O contacts forming –A–A–A– and –B–B–B– parallel chains propagating along the a-axis direction.


Comment
The title compound is an important organic intermediate which has been used to synthesis polydespipeptides and their copolymers, that have a wide range of biomedical applications such as, tissue engineering, drug delivery, and the synthesis of artificial skin (Feng et al., 2010). Herein we report on its crystal structure.
The two indepedent molecules of the title compound are shown in Fig. 1. In each molecule the NH hydrogen atom is hydrogen bonded to the adjacent O and Cl atoms (Table 1 and Fig. 1). Both molecules are planar with a maximum deviation of and , respectively for the mean planes of the non-H atoms.
The bond lengths (Allen et al., 1987) and angles are within normal ranges. The bond distances are similar to those observed for the trichloro derivative, (2,2,2-Trichloroacteyl)glycine (Dou et al., 1995), which also crystallizes with two independent molecules in the asymmetric unit.
In each molecule of the title compound the NH hydrogen atom is hydrogen bonded to the adjacent O and Cl atoms (Table 1 and (Table 1 and Fig. 2).

Experimental
The title compound was prepared by a method reported in the literature (Allmendenger et al., 1988). A solution of NaOH (93.75 ml, 4 mol/L) and 2-chloroacetyl chloride (22.6 ml, 0.3 mol) were added separately and slowly to a solution of N-(chloroacetyl)-glycine sodium salt [prepared by mixing NaOH (13.2 g, 0.3 mol) and glycine (25 g, 0.3 mol) at pH = 11 in an ice bath]. After stirring for 2 h at room temperature, HCl was added to adjust the pH to 2. Then ethyl acetate was added, and the solvent filtered. The organic phase was evaporated on a rotary evaporator and the title compound was obtained. Colourless block-like crystals were obtained by slow evaporation of an ethyl acetate solution for 5 days at room temperature.

Refinement
All H atoms were positioned geometrically and constrained to ride on their parent atoms: N-H = 0.86 Å, O-H = 0.82 Å, C-H = 0.97 Å with U iso (H) = 1.5U eq (O) and = 1.2U eq (C), while for the NH H atoms U iso (H) was refined.

N-(2-Chloroacetyl)glycine
Crystal data 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.