In a recent study published in ChemCatChem (Wiley-VCH), researchers developed recyclable iron-oxide nanoparticles which catalyze the synthesis of organosilicon compounds.
Organosilicon compounds are indispensable in materials science for manufacturing rubber, plastic and various other polymers. They are synthesized by introducing silicon groups into organic compounds, which requires the use of catalysts to facilitate and expedite the reaction. Traditionally, platinum is the go-to catalyst for this reaction, however, organic chemists are also experimenting with easily available transition metals such as iron. A research group led by Yasushi Obora at Kansai University has now reported the high potential of iron-oxide nanoparticles in efficiently carrying this chemical reaction forward.
The group has previously developed a simple, one-step method of synthesizing nanoparticles of iron, copper and platinum using N,N-dimethylformamide (DMF), a stabilizing chemical reagent. Because of their high surface area, nanoparticles are competent catalysts. Additionally, DMF is known to protect the nanoparticles. Therefore, the research group applied this method to synthesize nanoparticles of iron-oxide for their experiments.
The resulting nanoparticles were first characterized to understand their structure in detail. Using high-resolution imaging, such as transmission electron microscopy and light scattering, the researchers revealed the size of the particles to be 2 to 5 nm, well within the nanoparticulate range. Next, using X-ray─ and infrared-based spectroscopic techniques the interactions between DMF and iron-oxide particles were mapped. It was found that DMF enveloped the iron-oxide nanoparticles, possibly the mechanism behind its protective effects. In fact, DMF also made the nanoparticles resilient to heat treatment.
To test the functionality of these nanoparticles in facilitating the hydrosilylation reaction, 1-decene, an alkene with 10 carbon molecules was first used as the organic substrate. The particles successfully catalyzed the reaction, resulting in 84% of 1-decene being converted to the silylated form. The nanoparticles were also successful in converting other types of alkenes, including those with bulky cyclical carbon molecules in their structure. Upon completion of the chemical reaction, the nanoparticles were isolated from the reaction mix, only to find that their structure had remained intact. The researchers were also able to re-use those nanoparticles to catalyze up to five new batches of silylation reactions, without observing an ebb in their efficiency.
This study revealed the role of iron-oxide nanoparticles in facilitating organic silicon compound production. Not only were the particles themselves easy to produce, but they were also recyclable. “Further investigation into the detailed structure of the Fe-nanoparticle catalyst and its further application in catalysis are currently in progress”, concludes the research team.
Organosilicon compounds: Organosilicon compounds are composed of a basic skeleton of carbon and silicon bonds. Hydrosilylation is a commercial method of producing these compounds, wherein organic substrates such as alkenes, are treated with silicon derivatives in the presence of metals. The metal catalyst usually acts as an intermediary in the reaction. Besides being used as insulating materials in electric cables, production of plastics and rubber, organosilicon compounds also have applications in the cosmetics and pharmaceutical industries. Thus, streamlining production methods of these compounds is of great industrial value.
Ryusei Azuma, Seiya Nakamichi, Jungo Kimura, Hiroki Yano, Hideya Kawasaki, Takeyuki Suzuki, Ryota Kondo, Yasuharu Kanda, Ken-ichi Shimizu, Kazuo Kato, Yasushi Obora. Solution Synthesis of N,N-Dimethylformamide-Stabilized Iron-Oxide Nanoparticles as an Efficient and Recyclable Catalyst for Alkene Hydrosilylation. ChemCatChem, 2018. https://doi.org/10.1002/cctc.201800161