Highly Selective Hydroformylation of Vinylarenes to Branched Aldehydes by [Rh(cod)Cl]₂ Entrapped in Ionic Liquid Modified Silica Sol‐Gel

Abstract

A co-entrapped mixture of [Rh(cod)Cl] 2 and Na[Ph 2 P-3-(C 6 H 4 SO 3 )] within a silica sol-gel matrix modified with ca. 5 % of 1-butyl-3-[3-(trimethoxysilyl)propyl]imidazolium chloride catalyzes, in n-heptane, the hydroformylation of a variety of vinylarenes. At 50°C and under 6.9 bar each of H 2 and CO the reaction is high-yielding and highly selective. Nonhindered substrates give Ͼ95 % of branched aldehydes and only Ͻ5 % of the linear isomers. The ceramic catalyst is leach-proof and recyclable. It does not lose its high catalytic activity and selectivity for at least four runs. The selectivity

One‐Pot, Selective Hydroformylation, Condensation, and Hydrogenation Processes by a Sol–Gel Entrapped Rhodium Complex, an Immobilized Base, and an Ionic Liquid

“…The reaction of a mixture of 1 mmol styrene (1, R 1 = H), 1 mmol propanedinitrile (malononitrile, 3, R 1 = H, R 2 = R 3 = CN), 20.7 bar H 2 , and 20.7 bar CO in the presence of 2.04 ϫ 10 -2 mmol [Rh(cod)Cl] 2 co-entrapped with 4.01 ϫ 10 -2 mmol sodium 3-(diphenylphosphanyl)benzenesulfonate, ionic liquid confined silica sol-gel (vide infra), [4] and 10 mL of each of THF and 1,2-dichloroethane afforded, after 14 h at 80°C, a mixture of 86 % (2-phenylpropyl)propanedinitrile (5, R 1 = H, R 2 = R 3 = CN), [5] 7 % (2phenylpropylidene)propanedinitrile (4, R 1 = H, R 2 = R 3 = CN), [6] 2 % (3-phenylpropylidene)propanedinitrile (8), [7] and traces (Ͻ0.1 %) of its precursor 7. [8] The latter two products result from the linear aldehyde 6 formed in small quantities during hydroformylation.…”

“…[8] The latter two products result from the linear aldehyde 6 formed in small quantities during hydroformylation. [4] After removal of the products and addition of a new portion of the reagents and a base (vide infra), the used catalyst could be employed in a second run.…”

“…[2,3] In a recent study, we found that dichlorobis[(1,2,5,6-η)-1,5-cyclooctadiene]dirhodium, [Rh(cod)-Cl] 2 , that had been entrapped within an ionic liquid confined silica sol-gel promotes the hydroformylation of styrene derivatives in a highly selective manner to give mainly branched aldehydes. [4] In this paper, we show that by combining the aforementioned catalytic system with a suitable Scheme 1.…”

Enantioselective hydrogenation of itaconic acid and its derivates with sol–gel immobilized Rh/BPPM catalysts

“…A reason for the decreased specific surface area could be a blocking of the smaller pores in the support material by the immobilized catalysts. The average pore sizes of the catalysts were between 2.1 and 3.2 nm [5,7,26]. The TEM images of tetramethyl orthosilicate immobilized rhodium catalyst showed in Fig.…”

The Co‐Entrapment of a Homogeneous Catalyst and an Ionic Liquid by a Sol–gel Method: Recyclable Ionogel Hydrogenation Catalysts

“…[20] Vinylarenes could be selectively transformed into branched aldehydes. The ionogel catalyst exhibited moderate recycling ability.…”