Study of Catalytic Conversion of Organosilicon Compounds

尽管烃的催化反应已经完成了大量的工作，但对有机硅烷的转化进行的研究工作很少，尽管它们在各个领域的应用越来越重要。在实验室和工业中，有机硅烷的反应通常使用金属卤化物和过渡金属络合物在均相液相中进行。硅化合物在多相催化中的基础化学的发展是一个很有吸引力和重要的挑战，因此，本文研究了烷基硅烷的缩合和烷基化反应。1.烷基硅烷的歧化反应对于二乙基硅烷（E2）和二乙基二甲基硅烷（E2 M2）的缩合反应，只有强酸性催化剂，SiO_2-Al_2O_3（SA），氧化铝和硫酸化ZrO_2（SO_3/ZrO_2）催化剂具有较高的活性。在弱酸性催化剂上，裂化反应是有效的。虽然歧化反应只是在较低的反应温度下进行， 关于我们 在SiO_2-Al_2O_3和SO_3/ZrO_2上，有机硅烷的相对反应活性顺序为E_2M_2> E_2，而在Al_2O_3上的反应活性顺序为E_2> E_2M_2。这有力地表明，不同类型的机制是有效的;在Al_2O_3和SO_3/ZrO_2催化剂上，反应的起始步骤分别为氢的夺取和质子的加成。2.烷基硅烷的烷基化反应E2与烯烃如丙烯、1-丁烯、顺-2-丁烯、异丁烯、1，3-丁二烯和甲基乙炔在固体超强酸SO_3/ZrO_2催化剂上顺利发生。正烷基化产物是主要产物，而异烷基化产物是次要产物，与所使用的烯烃类型无关。结果表明，该反应是通过烯烃亲核进攻硅位进行的，产物分布与过渡金属配合物催化硅氢加成反应基本相同，这是国内外首次发现的有机硅化合物的多相催化转化反应.少

Although numerous works on catalytic reactions of hydrocarbons have been done, only few research works have been carried out on transformations of organosilanes, in spite of an increasing importance of their application to various fields. Both in laboratories and industries, reactions of organosilane are usually performed in a homogeneous liquid phase using metal halides and transition metal complexes. The development of fundamental chemistries of Si compounds in heterogeneous catalysis is quite attractive and important challenge.Hence the disproportionation and the alkylation of alkylsilanes were examined.1.Dispropotionation of alkylsialnesFor the disproportionation reaction of diethylsilane (E2) and diethyldimethylsilane (E2M2), only strongly acidic catalysts, SiO_2-Al_2O_3 (SA), alumina and sulfated ZrO_2 (SO_3/ZrO_2), exhibited high activities. On weakly acidic catalysts a cracking reaction was operative. Although the dispropotionation reaction was only the reaction at lower reacti … More on temperatures, an increase of reaction temperature resulted in the increase of the cracking reaction regardless the reactants and the catalysts.The relative reactivity of organosilanes was in the order of E2M2>E2 on SiO_2-Al_2O_3 and SO_3/ZrO_2, while the order on alumina was found to be E2>E2M2. This strongly suggests that differnt types of mechanisms are operative ; a hydride abstraction and a proton addition are the initiation step of the reaction over Al_2O_3 and SO_3/ZrO_2, respectively.2.Alkylation of alkylsilanesThe alkylation of E2 with olefins such as propene, 1-butene, cis-2-butene, isobutene, 1,3-butadiene and methylacetylene smoothly took place over an SO_3/ZrO_2 catalyst which is known as a solid superacid. n-Alkylated products were the main products and the iso-alkylated ones were the minor products regardless the type of olefins used. This suggests that the reaction takes place via nucleophilic attack of olefins on a silicocation.It is interesting finding that the product distribution is basically the same as that of the hydrosilylation catalyzed by transition metal complexes.These result is a first finding of the heterogeneous catalytic conversion of organosilicone compounds in the world. Less