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• 2633-67-2 4-vinylbenzenesulfonyl chloride 
• 107-15-3 ethylenediamine 

Relevant academic research and scientific papers

Alternative selective oxidation pathways for aldehyde oxidation and alkene epoxidation on a SiO2-supported Ru-monomer complex catalyst

We have prepared a novel Ru-mononer complex supported on a SiO2 surface by using a Rumonomer complex precursor with a p-cymene ligand, which was found to be highly active for the selective oxidation of aldehydes and the epoxidation of alkenes using O2. The structure of the supported Ru catalyst was characterized by means of FT-IR, solid-state NMR, diffuse-reflectance UV/vis, XPS, Ru K-edge EXAFS, and DFT calculations, which demonstrated the formation of isolatedly located, unsaturated Ru centers behind a p-cymene ligand of the Ru-complex precursor. The site-isolated Ru-monomer complex on SiO2 achieved tremendous TONs (turnover numbers) for the selective oxidation of aldehydes and alkenes; e.g. TONs of 38,800,000 for selective isobutyraldehyde (IBA) oxidation and 2,100,000 for trans-stilbene epoxidation at ambient temperature, which are among the highest TONs in metal-complex catalyzes to our knowledge. We also found that the IBA sole oxidation with an activation energy of 48 kJ mol-1 much more facile than the trans-stilbene epoxidation with an activation energy of 99 kJ mol -1 was completely suppressed by the coexistence of trans-stilbene. The switchover of the selective oxidation pathways from the IBA oxidation to the trans-stilbene epoxidation was explained in terms of energy profiles for the alternative selective oxidation pathways, resulting in the preferential coordination of trans-stilbene to the Ru-complex at the surface. This aspect gives an insight into the origin of the efficient catalysis for selective epoxidation of alkenes with IBA/O2.

Biomimetic catalysis with immobilised organometallic ruthenium complexes: Substrate- and regioselective transfer hydrogenation of ketones

Chloro-(η6-arene) complexes of ruthenium(II) with N-sulfonyl-1,2-ethylenediamine ligands that have one or two styrene side chains have been synthesised and characterised. The chloro ligand was substituted with a diphenylphosphinato ligand and the resulting organometallic complexes are transition state analogues for the ruthenium-catalysed transfer hydrogenation of benzophenone. Following the protocol of molecular imprinting, these complexes were copolymerised with ethylene glycol dimethacrylate (EGDMA) in the presence of a porogen. The polymers were ground and sieved, and the phosphinato ligand was substituted with a chloro ligand, thus generating a shape-selective cavity in close proximity to the catalytically active metal centre. When tested for their ability to catalyse the reduction of benzophenone, the imprinted polymers showed a significantly higher activity (up to a factor of seven) than control polymers without cavities. Out of a mixture of seven different aromatic and aliphatic ketones, benzophenone was preferentially reduced when the imprinted polymer was used. Furthermore, the specificity of the catalyst for diaryl ketones has been confirmed in a reaction with a bifunctional substrate, 4-acetyl-benzophenone; the diaryl ketone was reduced faster with the imprinted catalyst than the acetyl group. The opposite regioselectivity was observed with the control polymer. Both the activity and the selectivity of the imprinted catalysts are dependent on how the ruthenium complexes are attached to the polymer backbone. A double connection proved to give superior results.

Selective formation of a coordinatively unsaturated metal complex at a surface: A SiO2-immobilized, three-coordinate ruthenium catalyst for alkene epoxidation

(Chemical Equation Presented) Unsaturated but air-stable: A three-coordinate Ru complex, 2, highly active for alkene epoxidation and recyclable in air, was prepared on SiO2 by exploiting the exothermic reaction between O2 and isobutyraldehyde (IBA) to eliminate a p-cymene ligand from a coordinatively saturated precursor 1 (Ru red, Cl dark blue, N green, S yellow, O blue, C gray, H white). In contrast, direct activation with O2 alone was calculated to be endothermic.

Sulfoxidation on a SiO2-supported Ru complex using O 2/aldehyde system

A site-isolated SiO2-supported Ru-monomer complex, whose structure was characterized by means of solid-state NMR, XPS, UV/vis, and Ru K-edge EXAFS, was found to be efficient for sulfoxidation using an O 2/aldehyde system. Significant enhancement of sulfoxidation rates was observed on the SiO2-supported Ru complex for various sulfide derivatives.