| 叠氮二乙基铝三聚体和单体的缔合-解离平衡的研究 |
| Studies of Trimer-Monomer Equilibrium of Diethyl Aluminum Azide |
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| 摘要: 尽管叠氮二乙基铝Et2AlN3(DEAA)是一个重要的化合物,但人们对它研究还是很少的。本文通过温度-蒸气压关系研究了纯态DEAA的三聚体和单量体之间的缔合-解离平衡;通过相对分子质量测定、核磁共振氢谱和核磁共振铝谱的测定,研究了在苯和甲苯溶液中DEAA的三聚体和单量体之间的缔合-解离平衡。借助温度-蒸气压曲线分别计算了DEAA三聚体和单量体的气化焓和解离焓;通过相对分子质量测定、核磁共振铝谱测定等方法计算得到了溶液中DEAA三聚体和单量体的解离平衡常数、解离焓和解离熵等热力学数据。 |
| 关键词: 叠氮二乙基铝(DEAA) 相对分子质量测定 核磁共振氢谱 核磁共振铝谱 缔合-解离平衡 |
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| Abstract: The diethyl aluminum azide (DEAA) is an important compound in organic aluminum azides. But it was re-ported a little in the past. The temperature-vapor pressure diagram of diethyl aluminum azide is determined in this work. There are two straight lines, (1) and (2), which intersected at 123Pa and 86.6℃ in this diagram. There may be an equi-librium of trimer-monomer in the liquid state DEAA (3):lnp=-3.760×104/T+109.26(1);lnp=-1.014×104/T+32.90(2) (DEAA)3 3DEAA(3) Line (1) represents exchange from trimer of DEAA in liquid state to monomer in gas state. Line (2) represents exchange from monomer in liquid state to monomer in gas state. Thermodynamic data (ΔH(1),ΔH(2) and ΔHd) of the DEAA have been calculated from this two straight lines. The relative molecular weight of DEAA in benzene is determined by cryoscopic method. The relative molecular weight is always smaller than weight of (DEAA)3. This experiment demonstrates an equilibrium: (DEAA)3 3DEAA(4) The 1H NMR spectrum and the 27Al NMR spectrum of DEAA are determined in toluene at different tempera-tures. The equilibrium (4) is demonstrated with the chemical shifts δH and δAl of DEAA.The thermodynamic data (equilibrium constant Kd、 enthalpy exchange ΔH and entropy exchange ΔS) of the DEAA dissociation have also been calculated from these observed experimental values of relative molecular-weight de-termination and 27Al NMR determination. These thermodynamic data calculated in different methods are supported each other. |
| Keywords: diethyl aluminum azide (DEAA) molecular weight determination 1H NMR 27Al NMR association-dissociation equilibrium |
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| 高占先,张小航,冯立春.叠氮二乙基铝三聚体和单体的缔合-解离平衡的研究[J].无机化学学报,2002,18(7):654-658. |
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