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

Abstract

We report on a one-pot, multistep process in which styrene derivatives are selectively hydroformylated to give branched aldehydes, which in turn, are condensed with reactive methylene compounds (malononitrile, ethyl cyanoacetate), and then hydrogenated. The process takes place at 80°C under 20.7 bar H 2 and 20.7 bar CO in the presence of [Rh(cod)Cl] 2

Regioselective Hydroaminomethylation of Vinylarenes by a Sol–Gel Immobilized Rhodium Catalyst

“…All reagents and solvents of commercial grade were used without further purification. 1 H NMR and 13 C NMR spectra were recorded as CDCl 3 solutions on a 400 MHz NMR instrument. Infrared spectra were recorded on NaCl plates.…”

“…The sol−gel material, as well as the aqueous layer, were extracted with CH 2 Cl 2 (2 × 10 mL) to ensure complete removal of the products. The combined organic solutions were dried (MgSO 4 ), filtrated over silica column, concentrated and analyzed by GC, 1 H NMR and 13 C NMR. The heterogenized catalyst was dried at 80 °C and 0.1 Torr for 5 h in order to be ready for use in the next run.…”

“…11,12 The easily recyclable ceramic support also has the ability to perform one-pot multistep reactions in conventional organic solvents. 13 Reports on the use of microemulsions with organometallic catalysts for the hydroaminomethylation of olefins have, so far, been scarce. 14 In this contribution we describe the application of a new heterogeneous system based on [Rh(cod)Cl] 2 immobilized within a sol−gel matrix as a highly efficient, regioselective, and recyclable catalyst for the hydroaminomethylation reaction of vinylarenes with aniline derivatives under mild conditions.…”

Hydrogenation in Ionic Liquids

“…The systems potential for application in industry was demonstrated by, not only its selectivity, but its long-term stability arising from the ILs preventing the formation of active-site ensembles and therefore reducing catalyst deactivation by this way. Hamza et al [139] carried out hydrogenation as part of a one-pot multistep process. The process consisted of the hydroformylation of styrene derivatives to yield branched aldehydes.…”

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

“…Furthermore, this technique allows for immobilization of homogeneous catalysts in order to overcome the major drawback of homogenous catalysis, the difficult separation of the products and the catalyst after the reaction. Catalysts entrapped in sol-gel matrices can be used in a variety of reactions: ligand-free Heck and Suzuki couplings of aromatic compounds with Pd(OAc) 2 catalyst [3,4], the RhCl 3 ·H 2 O/Aliquat 336 catalyzed isomerization of hydrophobic allylarenes [5], hydroformylation of styrene derivates with [Rh(cod)Cl] 2 [6] and disproportionation of dihydroarenes with RhCl 3 ·H 2 O/Aliquat 336 or Pd(OAc) 2 catalysts [7]. The replacement of organic solvents by aqueous solutions with different surfactants (aqueous-micellar solutions or microemulsions) allows the more environmentally friendly performance of different reactions [8].…”