3,5⁃二甲基⁃4⁃羟基苯基五唑的热分解行为

Thermal Decomposition of 3,5⁃Dimethyl⁃4⁃hydroxyphenyl Pentazole

为了探究3,5‑二甲基‑4‑羟基苯基五唑的热分解行为,采用紫外‑可见光吸收光谱结合量子化学计算,对3,5‑二甲基‑4‑羟基苯基五唑(HMPP)随温度升高的热分解过程进行了追踪,并通过差示扫描量热仪测试了HMPP的热稳定性。结果表明:HMPP的初始分解温度为-14℃,其在紫外‑可见光区域由五唑环所产生的特征吸收峰在284 nm处,3,5‑二甲基‑4‑羟基苯基叠氮(HMPA)上的叠氮基所产生的特征吸收峰在258 nm处;随着温度的升高,整个体系在284 nm处的吸收峰逐渐降低。为了探究HMPP紫外可见光吸收光谱变化的具体原因,采用柱层析的方式分离HMPP的分解产物,利用核磁共振氢谱和X射线单晶衍射的方式对HMPP的分解产物进行了结构表征,确定了HMPP的主要分解产物为2,6‑二甲基对苯醌和4‑((4‑羟基‑3,5‑二甲基苯基)氨基)‑2,6‑二甲基环己‑2,5‑二烯‑1‑酮;并确定了在HMPP热分解结束后,整个体系的紫外‑可见光吸收是由化合物4和5的紫外‑可见光吸收叠加导致。

In order to explore the thermal decomposition behavior of 3,5‑dimethyl‑4‑hydroxyphenylpentazole,UV‑visible light absorption spectrum combined with quantum chemical calculation was adopted.The thermal decomposition of 3,5‑dimethyl‑4‑hydroxyphenylpentazole(HMPP)with increasing temperature was tracked.The thermal stability of HMPP was tested by differential scanning calorimeter.The results show that the initial decomposition temperature of HMPP is-14℃,and the characteristic absorption peak produced by the pentazole ring is at 284 nm in the UV‑visible region.The characteristic absorption peak of 3,5‑dimethyl‑4‑hydroxyphenyl azide(HMPA)is 258 nm.With the increase of temperature,the absorption peak of the whole system decreases gradually at 284 nm.In order to explore the specific reasons for the change of HMPP ultraviolet‑visible light absorption spectrum,the decomposition products of HMPP were separated by column chromatography.The main decomposition products of HMPP were 2,6‑dimethyl‑p‑benzoquinone and 4‑(4‑hydroxy‑3,5‑dimethylphenyl)amino)‑2,6‑dimethylcyclohexa‑2,5‑diene‑1‑one.After the thermal decomposition of HMPP,the uV‑visible absorption of the whole system was determined to be caused by the superposition of uV‑visible absorption of compounds 4 and 5.