升华剂2,4,6-三异丙基-1,3,5-三氧六环的晶体结构及其热力性质研究

以升华剂2,4,6-三异丙基-1,3,5-三氧六环为溶质,无水乙醇为溶剂,采用溶液挥发法培养了2,4,6-三异丙基-1,3,5-三氧六环的单晶.利用X-射线单晶衍射法测定其单晶结构,并通过紫外光谱、热重和X-射线粉末衍射等手段对其进行了表征.结果表明,标题化合物属于正交晶系,Pnma空间群,晶胞参数:a=0.827 7(3)nm,b=1.024 4(3)nm,c=1.683 1(5)nm,α=β=γ=90°,V=1.427 1(8)nm~3,Z=42,Mr=216.81,Dc=1.007g/cm~3,μ=0.070mm~(-1),F(000)=480.0,T=293(2)K,最终偏差因子(对I2σ(I)的衍射点)R1=0.083 7,wR2=0.264 8.化合物分子中的六元环呈椅式构型,分子间存在的弱氢键作用使得其沿c轴方向形成了一维无限链状结构.通过测量其饱和蒸气压随温度变化,按Clausius-ClaPeyron方程计算得出其升华焓为15.82kJ/mol,再结合热重TGA-DTA曲线、DSC曲线和焓变分析,可以判定升华剂在80℃之前没有发生分解产生新的物质.

Crystal structure and thermochemistry of sublimation agent 2,4,6-triisopropyl-1,3,5-trioxane

The crystal of 2,4,6-triisopropyl-1,3,5-trioxane was cultivated by the method of solution evaporation with the solute of 2,4,6-triisopropyl-1,3,5-trioxane and the solvent of anhydrous ethanol.The single crystal structure was determined by X-ray single crystal diffraction method.And the characterizations of the ultraviolet spectrum,thermogravimetric analysis and X-ray powder diffraction were also carried out.The structure indicated that the crystal is of orthorhombic,space group Pnma with a=0.827 7(3) nm,b=1.024 4(3) nm,c=1.683 1(5) nm,α=β=γ=90°,V=1.427 1(8) nm3,Z=42,Mr=216.31,Dc=1.007 g/cm3,μ=0.070 mm-1,F(000) =480.0,T=293(2)K,R1 =0.083 7,wR2 =0.264 8.The 1,3,5-trioxane in the molecule is a chair type configuration.A formation of a onedimensional infinite chain structure along the c axis direction is made by weakly hydrogen bonds between molecules.By measuring the saturation vapor pressure with temperature,the sublimation enthalpy calculated by Clausius-ClaPeyron equation was 15.821 kJ/mol.Combined with the analysis of TGA-DTA curves,DSC curve and the enthalpy,it can determine that the crystal did not decompose to produce new substances before 80 ℃.