(1R,2S)-N,N′-(1,2-Dihydroxyethylene)diformamide

The asymmetric unit of the title compound, C4H8N2O4, contains one half-molecule which is completed via a crystallographic inversion centre. In the crystal structure, molecules are arranged in undulating layers parallel to (001). Intermolecular N—H⋯O and O—H⋯O hydrogen bonds consolidate this arrangement.

The asymmetric unit of the title compound, C 4 H 8 N 2 O 4 , contains one half-molecule which is completed via a crystallographic inversion centre. In the crystal structure, molecules are arranged in undulating layers parallel to (001). Intermolecular N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds consolidate this arrangement.

Structure Reports Online
In a modified procedure we have synthesized compound (I) in much better yield and present its crystal structure in this communication.
Formally, compound (I) is a derivative of ethane with two hydroxyl and two formyl groups as substitutes of the corresponding H atoms. The asymmetric unit of compound (I) contains one half of the molecule that is completed via an inversion centre, leading to a R,S conformation for the two C atoms (Fig. 1). The bond lengths (Allen et al., 1987) and angles in the molecule are within normal ranges.
In the crystal structure, molecules are arranged in undulated layers parallel to (001). Intermolecular N-H···O and O-H···O hydrogen bonds consolidate this arrangement ( Fig. 2 and Table 1).
Experimental 76 mass parts of glyoxal monohydrate were stirred with 90 parts of formamide at room temperature. Then 6 mass parts of sodium bicarbonate were added. After 3 days, the crude crystalline product was washed with cold methanol and was dried, yielding 84.2 mass parts of 1,4-diformyl-2,3,5,6-tetrahydroxypiperazine (decomposition temperature 463 K). After filtering off the crystals, the aqueous mother liquor was kept at 273 K for 1 day and 2.2 mass parts of 1,2-dihydroxy-1,2-diformamidoethane were obtained (decomposition temperature 408 -413 K). Crystals suitable for structure determination were grown by recrystallization from dimethyl sulfoxide (DMSO).

Refinement
H atoms were positioned geometrically, with N-H = 0.88 Å (for NH), O-H = 0.86 Å (for OH) and C-H = 0.95 Å (for the aldehyde group) and and C-H = 1.00 Å (for the aliphatic C atom), and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (N, O, C). Fig. 1. The molecular structure of the title compound, drawn with displacement ellipsoids at the 50% probability level. H atoms are shown as spheres of arbitrary radius.