| Nano-alkali metal hydrides and lanthanide hydrides can be prepared easily by the direct hydrogenation catalyzed by TiCl4 in tetrahydrofunan (THF) under normal pressure. Lanthanide powder of nanometric size in a finely dispersed active form was generated by the thermal decomposition of organolanthanide in vacuum.1. Four kinds of model reactions were employed to draw comparisons of initial reaction rates between nano―NaH and the commercial one. The experimental results indicate that the initial reaction rates of nano-NaH are several orders of magnitude higher than those of the commercial one. The large specific surface area and the high surface energy of nano-NaH should be the main factors for their extremely high chemical reactivity. With nano―NaH, many reactions can be carried out efficiently.2. Using nano―LiH and nano―NaH as reducers, in refluxing THF and under normal pressure, cinnamaldehyde were selectively reduced to cinnamyl alcohol with selectivities of 99 % at higher conversions. Changing reaction temperature or the molar ratio between reactants and cinnamaldehyde can improve the selectivities and conversions. In addition, the sequence of the reactants is another factor to affect the selectivity and conversion in this reaction. 3. The reaction of lanthanide powder with anthracene in the presence of TiCl4 catalyst in tetrahydrofuran at 0-60℃under normal pressure generated organolanthanide compounds, which are less thermal. It was found that the decomposition of the organolanthanide compounds in vacuum could give rise to lanthanide powder of nanometric size with high purity accordingly. Transmission electron micrographs showed that the resulted lanthanide were in the form of nanoparticles with an average primary particle size around 20-40 nm. |
PDF Full Text Request