Dihydrazinium phosphate

Hydrazine Phosphates - Monohydrazinium Phosphate (N2H5H2PO4) and Dihydrazinium Phosphate [(N2H5)2HP04]... 

The product has been characterized by chemical analysis and IR spectra (z/n n at 960 cm ). Table 2.7 lists the type of bond and the peak position for mono- and dihydrazinium phosphates. The very similar N—N stretching frequency characteristic of N2H5 in both these salts indicates the presence of the same hydrazinium cation. 

Table 2.8 gives the TG and DTA results for monohydrazinium phosphate (N2H5H2PO4) and dihydrazinium phosphate, (N2H5)2HP04, along with the associated products formed. 

From the thermal decomposition of mono- and dihydrazinium phosphates it appears that both salts decompose through the intermediate formation of N2H5HP2O6 leading to metaphosphoric acid. Further, their decomposition patterns follow the corresponding decomposition pattern of ammonium salts. However, hydrazinium phosphate salts are of interest as superior flame retardants because of the hydrophilic nature or hygroscopic property of the hydrazinium ion. This supports dehydration more efficiently and limits the production of hydrocarbon gases, thereby promoting flame retardancy (see Chapter 6, Section 6.2.4). 

Monohydrazinium phosphate (MHP) and dihydrazinium phosphate (DHP) have also been investigated as flame retardants of cellulose and compared with the corresponding ammonium phosphates [6,7]. The flame retardant property of hydrazinium phosphates is checked using a Whatman No. 40 filter paper with an ash content of 0.018% as the cellulose source. This filter paper is treated with hydrazinium phosphates by dipping it into aqueous solutions of selected concentrations of 2.5% and 10% to ensure that the desired weight of phosphate is retained on the sample. The samples are then dried in air and used in pyrolysis experiments. 

Figure 6.3 shows the DTA curves of cellulose, monohydrazinium phosphate-treated cellulose, and dihydrazinium phosphate-treated cellulose. The DTA of cellulose exhibits a large exotherm at 377°C due to the oxidative degradation of cellulose and the oxidation of tarry products produced from the pyrolysis of cellulose. The first exothermic peak temperature is lowered from 377°C for pure cellulose to 277°C for... 

Table 6.3 summarizes mass spectrometric analysis data of the decomposition gaseous products of mono- and dihydrazinium phosphate, mono- and diammonium phosphate, and phosphoric acid treated celluloses. 

The ratio of the intensity of mass 18 to 44 (water and carbon dioxide, respectively) is higher for dihydrazinium phosphate-treated cellulose than for monohydrazinium phosphate-treated cellulose or even diammonium... 

Patil, K.C., Vittal, J.J., and Patel, C.C. (1981) Pyrolysis and combustion of a-cellulose effect of dihydrazinium phosphate (N2H5)2HP04. Thermochimica Acta, 43,213-219. 

Hydrazine forms two main salts with the hydrogen phosphate anions H2PO4 and HP04 as mono- and dihydrazinium salts. 

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