FOX-7的晶体结构和热分解特性

Crystal Structure and Thermal Decomposition of FOX-7

以2-甲基-4,6-嘧啶二酮为原料,通过硝化、水解反应,合成出1,1-二氨基-2,2-二硝基乙烯(FOX-7),产率为85.1%,并用元素分析、红外、质谱、核磁进行表征。以乙腈为溶剂培养得到了FOX-7单晶,用X射线单晶衍射仪测定晶体结构。结果表明,晶体属单斜晶系,空间群为P 21/n。晶体学参数为:a=0.693 0(14)nm,b=0.6630(13)nm,c=1.1360(2)nm,β=90.43(3),°V=0.5219(18)nm3,Z=4,Dc=1.885 g.cm-3,μ=0.179 mm-1,F(000)=304。用DSC和TG-DTG技术研究了热分解过程。结果表明,FOX-7分解由一个吸热和两个放热过程组成,吸热峰由晶型转变引起,放热峰由分解所致;TG曲线由两个失重过程组成;较高的分解温度表明FOX-7有较好的热稳定性。

1, 1-Diamino-2, 2-dinitroethylene （FOX-7） was synthesized with 2-methylpyrimidine-4, 6-dione as primary substance by nitration and hydrolysis steps in turn. The yield is 85. 1%. The structure of the obtained compound has been identified by elemental analysis, IR, MS and NMR. The single crystal of FOX-7 was cultivated from acetonitrile. Its crystal structure was determined by a X-ray single crystal diffractometer. The results show that the crystal is belong to monoclinic system, space group P21/n, with crystal parameters of a= 0. 6930 （14）nm, b=0. 6630（13）nm, c=1. 1360（2）nm,β=90.43（3）°, V=0, 5219（18）nm^3, Z=4, Dc=1. 885 g · cm^-3,μ = 0. 179 mm^-1, F （000）= 304. Its thermal decomposition mechanism was studied by DSC and TG-DTG techniques. The thermal decomposition of FOX-7 consists of one endothermic and two exothermic decomposition processes continuously. The TG curve consists of two stage mass loss processes. The endothermic peak is attributed to the crystal transformation and the exothermic peaks are due to the decomposition reaction of FOX-7 and its decomposition products. Higher decomposition temperature shows that FOX-7 has better thermal stability.