氧气与气-液两相偏二甲肼作用的氧化产物及其反应机理

Oxidation Products and Reaction Mechanism of O_2 and Gas-liquid Two Phase UDMH

为了探究偏二甲肼(UDMH)在实际贮存中的失效机理,利用气相色谱-质谱(GC-MS)法测定了在氧气、氧气/水、空气、空气/水4种条件下气-液两相偏二甲肼与氧气、空气的液相反应产物,以及主要气相产物含量随时间的变化,并分析了其反应机理。结果表明,偏二甲肼的氧化产物多达19种,其中亚硝基二甲胺(NDMA)、偏腙、二甲胺、水、N,N-二甲基甲酰胺为主要产物,新检测到的4种产物为N,N,N′,N′-四甲基甲烷二胺、4-甲基脲唑、三(二甲氨基)甲烷和不对称二甲脲。氧气与气相偏二甲肼的氧化极大提高了强致癌物NDMA的生成,其中已降解偏二甲肼中有30%转化为NDMA,气相中NDMA质量分数高达1.3%;而偏二甲肼与空气作用,NDMA的生成率约5%。因此,可通过降低氧气含量避免偏二甲肼的失效和NDMA的生成。

To explore the failure mechanism of unsymmetrical dimethylhydrazine（UDMH）in the actual storage,liquid phase reaction products of gas-liquid two-phase UDMH with O2 and air,and the change in the content of main gaseous products with time,under the four kinds of conditions of oxygen,oxygen/water,air and air/water,were determined by gas chromatography-mass spectrometry（GC-MS）and their reaction mechanisms were analyzed.The results show that there are 19 kinds of oxidation products of UDMH,of which,nitrosodimethy lamine（NDMA）,unsymhydrazone,dimethylamine,water and N,N-dimethylformamide as main products,as well as four newly detected products as N,N,N′,N′-tetramethylmethylenediamine,4-methyl urazole,tris（dimethylamino）methane and unsym-dimethylurea.The oxygen and oxidation of UDMH in the gas phase greatly enhances the generation of NDMA,which is a kind of strong carcinogen.Among them,30% of the degraded UDMH are converted to NDMA and the mass fraction of NDMA in the gas phase is up to 1.3%,whereas the generation rate of NDMA in the reaction with air is about 5%.Therefore,the decrease of of oxygen content can avoid the failure of UDMH and the generation of NDMA.