Thermochemical behaviour of lanthanum complexes of 2-ethylhexyl phosphoric acid

Abstract

The thermochemical behaviour of solid-state complexes of lanthanum with mono-(2-ethylhexyl) phosphoric acid (H2B) (La(HB)yl.5H20 and La2By3H20) was studied. The thermal decomposition of these complexes proceeds without melting to yield La(PO3)3 and a mixture of La(PO3)3 and LaPO4, respectively. La(HB)yl.5HzO decomposes via dehydration (323-383 K), condensation of the OH-groups with formation of a diphosphate structure (383-458 K) and a stepwise degradation of the hydrocarbon chains (443-565 K). The dehydration of LazBy3H20 (333-433 K) is followed by decomposition of the hydrocarbon group. From a combination of the present results with previous data [1], it was concluded that the temperatures and mechanisms of the decomposition of the hydrocarbon part of the lanthanide complexes of (2-ethylhexyl) phosphoric acids depend on the nature of the lanthanide, the atmosphere, and the structure of the complexes.