Synthesis, crystal structure of 2,4-dihydroxybenzoic acid lead and its catalytic decomposition effect on AP and RDX

Abstract

2,4-Dihydroxybenzoic acid lead (β-Pb) was synthesized and its single crystal structure was reported firstly. β-Pb crystallizes in monoclinic system with space group of C2/m and crystal parameters of a=17.888(3) Å, b=4.8790(8) Å, c=21.408(4) Å, β=100.258(5) °, Z=2, V=1838.5(5) Å3, μ=12.213 mm−1, F(000) = 1000.0 and Dcalc = 1.920 g/cm3. 2,4-Dihydroxybenzoic acid presents a monoacid form only, two different coordination forms of Pb2+ exist in crystal structure of β-Pb, and the two phenolic hydroxyl groups all do not involved in coordination with lead ions. The thermal decomposition of β-Pb and its catalytic effect on thermal decomposition of AP and RDX were explored. For AP, the low-temperature decomposition temperature (LTT) and high-temperature decomposition temperature (HTT) decrease by 30.4 °C and 31.3 ℃ with the addition of β-Pb, and their apparent activation energies (Ea) decrease by 44.4 kJ/mol and 31.6 kJ/mol, respectively. For RDX, the thermal decomposition temperature and Ea decrease by 11 °C and 110.7 kJ/mol respectively, after the addition of β-Pb. β-Pb shows excellent catalytic decomposition effect on AP and RDX.