Hydrazinium hydrazine carboxylate

To prepare a carbonate salt of the dihydrazinium cation by the route (2.13), where ammonium carbonate is dissolved in hydrazine hydrate. Notably, when this reaction is attempted, instead of a carbonate salt of hydrazine being formed a viscous, syrupy liquid is obtained. The liquid has been shown to be hydrazinium hydrazine carboxylate (N2H5COON2H3) [23]. This occurs because commercial ammonium carbonate is a mixture of ammonium bicarbonate and ammonium carbamate (NH4HCO3 NH2COONH4). The probable reaction is shown below ... 

Hydrazinium hydrazine carboxylate is used in the preparation of 4-amino-3,5-dimethyl-l,2,4-triazole, a useful compound in agriculture and medicine. When a mixture of viscous liquid hydrazinium hydrazine carboxylate and acetonitrile is kept at room temperature, two layers appear the top layer being acetonitrile and the lower one N2H5COON2H3. A pink color develops in the acetonitrile layer after about 12 h. After two to three weeks, a white crystalline compound is formed in the hydrazinium hydrazine carboxylate layer, and the pinkish acetonitrile layer disappears. The white crystals are those of 4-amino-3,5-dimethyl-l,2,4-triazole. 

The synthesis of 4-amino-3,5-dimethyl-l,2,4-triazole is also carried out using hydrazinium hydrazine carboxylate as the starting material it is boiled under reflux with acetonitrile (20 ml) for 4h [5]. The resultant solution is evaporated over a water bath to afford colorless crystals of the triazole. The crystals are separated by filtration and washed with a small amount of acetone followed by acetonitrile, and then dried in air to give the product (1.3 g). The compound is freely soluble in DMSO and water, slightly soluble in acetone, and insoluble in benzene, carbon tetrachloride, chloroform, and acetonitrile. 

Hydrazine hydrate is known to react with acetonitrile in the presence of sulfur or ethanol to form 4-amino-3,5-dimethyl-l,2,4-triazole or 3,6-disubstitued-l,2-dihydro-l,2,4,5-tetrazines. The initial product, which is disubstituted l,2-dihydro-l,2,4,5-tetrazine, is readily oxidized to the pink colored 1,2,4,5-tetrazine it may also rearrange at elevated temperature or on treatment with an acid to the corresponding 1,2,4-triazole. The triazole compound is obtained by the reaction of hydrazine hydrate and acetonitrile in the presence of CO2. The presence of CO2 in the formation of the six-membered ring intermediate is essential, and has been confirmed by repeating the experiments in the absence of CO2. However, the exact role of CO2 in this reaction is not clear. Figure 6.1 gives a possible mechanism for the formation of the triazole from hydrazinium hydrazine carboxylate and acetonitrile. 

Many of the iV-alkyl and iV-aryl derivatives of urazine have been synthesized and characterized, but the parent substance is not well known. In the past, urazine has been prepared by thermal deammonation of carbohydrazide-iV-carboxamide [eq. (I)],1 fusion of hydrazidicarbamide with hydrazinium hydrogen sulfate [eq. (2)],2 fusion of earbohy-drazide with urea [eq. (3)],3 action of sodium hypobromite on semicarbazide [eq. (4)],4 reaction of dichlorourea with concentrated ammonia [eq. (5)],5 and the reaction between 1,2 hydrazine carboxylic ester and hydrazine hydrate... 

When hydrazine carboxylic acid is dissolved in anhydrous hydrazine it probably exists in the form of a hydrazinium carboxylate salt that dissociates into hydrazine carboxylate anion and hydrazinium cation. It is a bidentate ligand and forms coordination compounds with metal ions ... 

HYDRAZINIUM METAL HYDRAZINE CARBOXYLATE HYDRATES -N2H5M(N2H3C00)3 H2O... 

Interestingly, manganese does not readily form the hydrazinium complex although manganese hydrazine carboxylate hydrate and hydrazine complexes are formed. 

Similar to iron hydrazine carboxylate hydrazine (Fe(N2H3COO)2-(N2H4)2), the iron hydrazinium complex (N2H5Fe(N2H3C00)3-H20)... 

The hydrazinium nickel hydrazine carboxylate complex, (N2H5)Ni (N2H3C00)3-H20, is also used as precursor for the synthesis of metallic Ni in the sonochemical preparation of Ni-Mo-S/Al203, since volatile Ni precursors such as Ni(CO)4 are exceptionally toxic and dangerous to use [24]. Similarly, copper hydrazine carboxylate is used to prepare nanoparticles of copper by the sonication method [25]. The presence of a zwitterionic surfactant in the synthesis procedure causes the formation of elongated nanoparticles of aspect ratio 10, which is of significance for electrical applications. In the absence of the zwitterionic surfactant only spherical particles result [26]. 

Cobalt-Substituted Hydrazinium Iron Hydrazine Carboxylate Hydrate... 

Single crystals of Mn-doped hydrazinium zinc hydrazine carboxylate hydrate [N2H5Mno.o2Zno.9g(N2H3COO)3 H20] are prepared by the method described in Section 4.5. Pale pink crystals of the complex are obtained in a couple of days, and the presence of is confirmed by... 

SOLID SOLUTIONS OF HYDRAZINIUM METAL HYDRAZINE CARBOXYLATE HYDRATES - N2H5 Mv (Co/Ee/Mn)22 (N2H3COO)3 H2O... 

Table 4.8 Unit cell dimensions for the monoclinic hydrazinium metal hydrazine carboxylate hydrates and their solid solutions.

The combustion of mixed metal iron complexes is similar to that observed for hydrazinium metal iron hydrazine carboxylates. The combustion is autocatalytic, once ignited, and leaves behind voluminous mixed ferrites. The particulate properties of these oxides such as cobal-tites, ferrites and mixed ferrites have been investigated [32]. 

Quite recently, a soUd solution of hydrazinium mixed metal hydrazine carboxylate complex of the type (N2H5)Nio.5Coo.5(N2H3COO)3-H20 has been prepared by mixing the respective metal solutions in a molar ratio of 1 1 [4]. To this solution hydrazine carboxylic acid is added until... 

Hydrazinium mixed metal hydrazine carboxylate complexes of Ni and Co act as a precursor to a bimetallic nano-size powder of Nio.5Coo.5. Overall, it is inferred that metal hydrazine carboxylate derivatives are potential precursors for generating nanocrystalline structures. 

The reaction between metal thiocyanates and hydrazinium thiocyanates cannot be used to prepare hydrazinium metal thiocyanate complexes. Consequently, an alternate method is employed, namely, the decomposition of hydrazinium metal hydrazine carboxylates with dilute thiocyanic acid (<5%) [27,28]. Hydrazinium metal hydrazine carboxylates complexes N2H5M(N2H3C00)3 H20, where M = Co and Ni, are prepared from metal nitrates, sulfates, or chlorides and hydrazine hydrate saturated with carbon dioxide. The dilute thiocyanic acid is prepared by adding barium thiocyanate trihydrate to dilute sulfuric acid. 

Similar to hydrazinium metal sulfates, hydrazinium metal sulfite complexes can be synthesized the procedure is, though, slightly different. Hydrazinium transition metal sulfite dihydrate complexes of the formula (N2H5)2M(S03)2(H20)2 where M = Fe, Co, Ni, Cu, and Zn are prepared from metal hydrazine carboxylates (described in Chapter 4) as the starting material. In this method, the anhydrous metal hydrazine carboxylate, M(N2H3C00)2, is added to distilled water previously saturated with sulfur dioxide gas. The complex decomposes with the liberation of carbon... 

Analogous to the synthesis method adopted for the preparation of hydrazinium metal sulfite hydrates, hydrazinium lanthanide sulfite hydrates, N2H5Ln(S03)2(H20)2, can be synthesized by the addition of hydrazine sulfite monohydrate to the respective anhydrous lanthanide hydrazine carboxylates M(N2H3COO)2 [10]. 

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