Crystal structure of N-(2,2,2-trichloro-1-hydroxyethyl)formamide

The title compound, crystallized with two conformationally similar molecules (A and B) in the asymmetric unit. In the crystal, individual molecules are linked by pairs of O—H⋯O hydrogen bonds, forming A–A and B–B inversion dimers with (12) ring motifs.


Chemical context
The skeletal structure of formamide is present in a number of medicinally important compounds. This has led to the use of formamides as key intermediates in numerous organic synthetic endeavours (Kobayashi et al., 1995;Chen et al., 2000;Jackson & Meth-Cohn, 1995). While formamides are useful formylating agents they have also found utility as easily accessible Lewis bases for promoting several organic transformations (Kobayashi & Nishio, 1994). Furthermore, in peptide synthesis the formyl group is a valued aminoprotecting group (Martinez & Laur, 1982;Kraus, 1973). The title compound and related molecules have been found mentioned in several old patent literatures owing to their biocidal properties; both herbicidal (Schiewald et al., 1974) and fungicidal (Summers & Carter, 1977) action is known. The title compound is easily obtained by the reaction of 2,2,2trichloroacetaldehyde and formamide (Sethi, 2006) and we describe herein its crystal structure.

Structural commentary
The title compound, Fig. 1, crystallized with two independent molecules (A and B) in the asymmetric unit. The arbitrarily ISSN 2056-9890 chosen chirality of atoms C2 in molecule A and C5 in molecule B is the same. The backbones of the two molecules (O1/O3, C1/C4, C2/C5, N1/N2, C3/C6 and O2/O4) have almost identical conformations with weighted and unit-weight r.m.s. overlay fits of 0.047 and 0.043 Å , respectively, for the six atoms in each molecule (Fig. 2).

Figure 3
A view along the a axis of the hydrogen-bonded layer of A molecules of the title compound. Hydrogen bonds are shown as dashed lines (see Table 1) and C-bound H atoms have been omitted for clarity.
concern metal complexes of the ligand N-(hydroxymethyl)nicotinamide. Only one compound, N,N 0 -(1,2-dihydroxyethylene)diformamide (OGEJUG; Taheri & Moosavi, 2008) resembles the title compound. In the solid state, the whole molecule of this compound is generated by inversion symmetry. The geometric parameters are similar to those observed for the title compound, for example the conformation of the N-(hydroxmethyl)formamide chain as indicated by the C-N(H)-C-O(H) and C-N(H)-C O torsion angles: 1.6 (2) and À99.09 (14) for the above mentioned compound compared to À1.8 (3) and À91.5 (2) for molecule A and À2.1 (3) and À95.7 (2) for molecule B of the title compound (see Fig. 1).

Synthesis and crystallization
The title compound can be synthesized following a literature procedure (Sethi, 2006), by the reaction of 2,2,2-trichloroacetaldehyde and formamide. An old and discoloured sample of N-(2,2,2-trichloro-1-hydroxyethyl)formamide was dissolved in hot ethanol, followed by treatment with charcoal. The filtered solution was left to crystallize by slow evaporation, forming colourless block-like crystals (m.p. 393 K).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. All of the H atoms were located from difference Fourier maps and freely refined.

Figure 4
A view along the a axis of the hydrogen-bonded layer of B molecules of the title compound. Hydrogen bonds are shown as dashed lines (see Table 1) and C-bound H atoms have been omitted for clarity.

Figure 5
A view along the b axis of the crystal packing of the title compound, showing the alternating layers of hydrogen-bonded A (blue) and B (red) molecules. Hydrogen bonds are shown as dashed lines (see Table 1) and C-bound H atoms have been omitted for clarity.  N-(2,2,2-trichloro-1-hydroxyethyl)formamide

Special details
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.