K. Fukushima et al., THERMAL-BEHAVIOR OF GUANIDINIUM DIHYDROGE NPHOSPHATE AND DIGUANIDINIUM HYDROGENPHOSPHATE, Nippon kagaku kaishi, (2), 1996, pp. 146-153
The thermal decompositions of four kinds of guanidinium salts, such as
guanidinium dihydrogenphosphate(1), diguanidinium hydrogenphosphate(2
), diguanidinium carbonate(3), and guanidinium nitrate(4), were invest
igated. The thermal behaviors of these samples under a nitrogen atmosp
here differ from one another. In GC/MS measurements of volatile produc
ts generated by the thermal decomposition for these samples, major fra
gment ions were confirmed as water, ammonia, isocyanic acid, and carbo
n dioxide. Further, from the mass spectrometry and IR analysis of vola
tile products for four kinds of samples, the formation of identical gu
anidine derivative during thermal decomposition process was confirmed
in all cases. In IR analyses for residues of 1 and 2 heated to various
temperatures, their spectra differed from each other until temperatur
e raised at 300 degrees C. Above 300 degrees C, the infrared band of g
uanidinium ion completely disappeared and then the thermal products of
both samples showed identical spectra. Above 500 degrees C, polymetap
hosphates and diphosphorus pentaoxides were formed by the thermal deco
mposition and subsequently occurred condensation reactions. The kineti
cs were partially resolved and activation energies were estimated for
the thermal decomposition of guanidinium phosphates. The highest value
of activation energies for 1 and 2 were observed at weight loss of ab
out 20%. We suggest that guanidinium phosphates decomposed through the
formation of guanidine and urea derivatives, such as biguanide and am
idinourea.