液相法合成α-AlH_3的工艺改进

Improved synthesis of α-AlH_3 in liquid phase

研究了LiAlH4与AlCl3在无水乙醚中反应制得固体AlH3醚合物,再在惰性溶剂中加热脱醚制备α-AlH3的方法。考察了脱醚反应中添加LiBH4、温度与时间、溶剂和促结晶剂(聚二甲基硅氧烷)对产品的影响。试验结果表明,最佳工艺条件为试验以LiAlH4∶AlCl3摩尔比为4∶1反应,减压蒸除乙醚制得固体AlH3醚合物;脱醚反应以甲苯为溶剂,固体AlH3醚合物与LiBH4摩尔比为4∶1,添加适量促结晶剂,在90℃下脱醚反应2 h。采用此工艺可制得结晶为立方体、性质稳定的α-AlH3,纯度为96.0%,收率达96.4%。

α-AlH3 was synthesized in an inert solvent by desolvation of solid AlH3 -etherate, which was obtained from the reac- tion of LiAlH4 and AlCl3 in ether.The effects of LiBH4 addition, temperature and time, solvent, crystallizing agent in desolvation on the product were discussed.The optimum process conditions were as follows：the molar ratio of LiAlH4 and AlCl3 was 4 ： 1, the solid AlH3-etherate was obtained by vacuum distillation;the desolvation was operated in toluene at 90 ℃ for 2 hours in the presence of crystallizing agent,the molar ratio of solid AlH3-etherate and LiBH4 was 4 ： 1. In this process, α-AlH3 with cubical crystallization and high stability was prepared in the purity of 96.0 % and yield of 96.4 %.