Unexpected Stereospecific Rearrangement-Addition Reaction of Trisubstituted Gibberellin Epoxides with Trimethylaluminium

A novel rearrangement-addition reaction of trisubstituted gibberellin epoxides with trimethylaluminium is reported. The reaction proceeds stereospecifically to give tertiary methyl alcohols. The possible mechanism for the reaction is also discussed.

Density functional theory (DFT) and ab initio investigations of the electronic and molecular structures of the monomer and the dimer of trimethylaluminium

The electronic and molecular structures of the monomer and dimer of trimethylaluminium have been studied using density functional theory and ab initio MP2 method. The optimized geometry of the monomer Al(CH3)3 is of C3h symmetry, whew that of the dimer [Al(CH3)3]2 contains a carbon-bridged four-membered ring structure with C2h symmetry. The hydrogen-bridged six-membered ring structure is found to be unstable. The calculated dimerization energy for the four-membered ring structure is 78 kJ/mol, in close proximity to the experimental due of 85.27 kJ/mol.

TMA脉冲和吹扫时间对原子层沉积的氧化铝薄膜的影响

采用原子层沉积技术(ALD)进行Al_2O_3薄膜工艺研究,获得85℃低温Al_2O_3薄膜ALD的最佳工艺条件。使用椭偏仪测试厚度,使用扫描探针显微镜对薄膜表面形貌进行分析,使用紫外-分光光度计对薄膜的透过率进行分析,所用水汽透过率测试仪器是自行开发的基于钙电学法的测试仪器。分析了在85℃低温下的生长工艺条件对薄膜性能的影响,从前驱体脉冲时间,吹扫时间等工艺条件,对Al_2O_3薄膜的工艺条件进行优化。以三甲基铝(TMA)和H_2O为前驱体制备的Al_2O_3薄膜:沉积速率为0.1nm/cycle,表面粗糙度为0.46nm,对550nm波长光透过率为99.2%,薄膜厚度不均匀性为1.89%,200 nm的Al_2O_3薄膜的水汽透过率为1.55×10^(-4) g/m^2/day。

三甲基铝(TMA)合成与模试研究

研究了三甲基铝合成的溶剂、原料、加料及合成条件等因素对合成反应的影响,确定了合成三甲基铝的配方及反应条件。以癸烷和二甲苯的混合物为假物料,对三甲基铝(TMA)模试装置进行了模拟试验,提出了在该模试装置上生产三甲基铝的方法。在模试生产中,TMA的合成反应在常压、120℃下进行,对反应产物采用恒组成精馏分离操作并控制常压、分离柱温度95～110℃、每一批反应产物精馏时间约15h,可制备纯度为97.67%的TMA。以此TMA合成的MAO的收率为46%。当聚合条件为Al/Zr=500,溶剂为己烷,聚合温度80℃,聚合时间1h时,乙烯均相聚合活性为1.37×105g/molZr·h。