Homoallylic alcohol isomerization in water over an immobilized Ru(II) organometallic catalyst with mesoporous structure

摘要

PPh2-functionalized SBA-15 was synthesized by co-condensation of tetraethyl orthosilicate and 2-(diphenylphosphino) ethyltriethoxysilane through prehydrolysis. The as-prepared PPh2-SBA-15 was used as the support to immobilize the Ru(II) organometallic catalyst through the strong coordination between the Ru( II) and the PPh2-ligand (Ru-PPh2-SBA-15). During 1-phenyl-3-buten-1-ol isomerization carried out in water as an environmentally friendly medium, the Ru-PPh2-SBA-15 catalyst exhibited almost the same activity and selectivity as the corresponding RuCl2(PPh3)(3) homogeneous catalyst and could be used repetitively nearly 7 times. On the basis of various characterizations, the correlation of the catalytic behaviors of the Ru-PPh2-SBA- 15 to its structural characteristics was discussed briefly. Obviously, the high activity of the Ru-PPh2-SBA- 15 could be attributed to both the high surface area of the support, which ensured the good dispersion of Ru( II) active sites, and the ordered mesoporous structure, which facilitated the diffusion of organic reactants.