Synthesis and crystal structure of N 1,N 2-dimethylethanedihydrazide

In the title compound, the two hydrazide planes make a dihedral angle of 86.5 (2)°. In the crystal, C—H⋯O, N—H⋯O and N—H⋯N hydrogen bonds lead to the formation of a three-dimensional supramolecular network.


Chemical context
For over a century, researchers have aimed to synthesize diverse heterocycles using well-established available methods.Currently, there is significant research interest in developing new methods for their synthesis, focusing on efficient and atom-economical routes (Favi, 2020;Pathan et al., 2020).Among these novel synthetic approaches, the utilization of hydrazides stands out as one of the most appealing methods for synthesizing heterocyclic compounds such as pyrazoles, triazoles, oxadiazoles and pyridazines (Majumdar et al., 2014;Mittersteiner et al., 2021;Hosseini & Bayat, 2018;Khomenko et al., 2022).
Considering the above, we report on the synthesis and crystal structure of a new alkylated oxalyl dihydrazide as an attractive synthon for the synthesis of biologically active organic compounds and metal complexes.

Structural commentary
The title compound crystalizes in the orthorhombic Sohncke space group P2 1 2 1 2 1 with four formula units per unit cell (Fig. 1).The crystal structure does not show other tautomeric forms.Bond lengths and angles are given in Table 1.The geometrical parameters are comparable to the values found in methylsemicarbazide (Szimhardt & Stierstorfer, 2018) and oxalyl dihydrazide (Quaeyhaegens et al., 1990)

Figure 1
The molecular structure of the title compound with atom labeling and displacement ellipsoids drawn at the 50% probability level.
A search for the methyl hydrazide moiety gave methylsemicarbazide (XIBFEW; Szimhardt & Stierstorfer, 2018).Its geometric parameters agree well with those of the title compound.Further searches also revealed two structural analogues with a second non-hydrogen substituent at the amide-nitrogen atom: N,N,N 0 ,N 0 -tetramethyloxamide and N,N,N 0 ,N 0 -tetramethylmonothiooxamide (TMOXAM and TMTHOX, respectively; Adiwidjaja & Voss, 1977).These two crystal structures have a different packing and belong to monoclinic space groups.However, they exhibit very similar geometries in terms of the rotation of the molecule fragments around the central C-C bond.The O C-C O(S) torsion angles are 105.1 (2) and 89.6 (2) � , respectively.

Synthesis and crystallization
The title compound (5) was obtained according to the reaction scheme shown in Fig. 4.
N 1 ,N 2 -dimethylethanedihydrazide (5): 11.0 g (79.7 mmol, 3 eq.) of K 2 CO 3 and 3.65 ml (58.6 mmol, 2.2 eq.) of CH 3 I were added to a solution containing 10.0 g (26.5 mmol, 1 eq.) of compound 3 in 50 ml DMF.The reaction mixture was stirred for 6 h at room temperature.The inorganic precipitate was filtered off, the filtrate was evaporated and the residue was stirred in water, filtered off and dried in air.Yield: 9.9 g.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3.For the NH 2 group, the hydrogen atoms were placed from a difference-Fourier map and refined freely.The CH 3 hydrogen atoms were placed geometrically and refined as riding with C-H = 0.96 A ˚and U iso (H) = 1.5U eq (C).

A
search of the Cambridge Structural Database (CSD, version 5.43, last update November 2021; Groom et al., 2016) confirmed that the title compound has not previously been published.A search for the N-N-C( O)-C( O)-N-N fragment gave oxalyl dihydrazide (CSD refcode VIPKIO;

Figure 3 A
Figure 3 A view normal to plane (100) of the crystal structure of the title compound, showing the three-dimensional supramolecular hydrogenbonding network.

Figure 4
Figure 4Synthesis of the title compound.

Table 3
Experimental details.