Study of Catalytic Conversion of Organosilicon Compounds

尽管人们对烃类化合物的催化反应进行了大量的研究，但有机硅烷的转化研究却很少，尽管有机硅烷在各个领域的应用日益重要。在实验室和工业中，有机硅烷的反应通常是在均相液体中使用金属卤化物和过渡金属络合物进行的。硅烷化合物的基础化学在多相催化中的发展是一个非常吸引人的领域，也是一个重要的挑战。因此，烷基硅烷的歧化和烷基化反应被考察了。1.烷基硅烷的歧化对于二乙基硅烷(E_2)和二甲基硅烷(E_2M_2)的歧化反应，只有强酸性催化剂SiO_2-Al_2O_3(SA)、氧化铝和硫酸化的ZrO_2(SO_3/ZrO_2)表现出高活性。在弱酸性催化剂上，裂化反应是可操作的。尽管歧化反应只是低反应性…下的反应有机硅烷在SiO_2-Al_2O_3和SO_3/ZrO_2上的相对反应活性为E2M2&GT；E_2，而在氧化铝上的相对反应活性为E_2&GT；E_2M_2。2.烷基硅烷的烷基化反应在固体超强酸SO_3/ZrO_2催化剂上进行。E_2与丙烯、1-丁烯、顺-2-丁烯、异丁烯、1，3-丁二烯和甲乙炔的烷基化反应顺利进行。无论使用的是哪种烯烃，N-烷基化产物是主要产物，异烷基化产物是次要产物。有趣的是，该反应的产物分布与过渡金属络合物催化的硅氢加成反应基本相同，这是世界上首次发现有机硅化合物的多相催化转化。较少

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