10.1002/chem.201001703
The research explores the use of sintered silicon carbide (SiC) as a novel ceramic material for reaction vessels in microwave chemistry. The purpose of this study is to leverage SiC's high microwave absorptivity, thermal conductivity, and chemical inertness, which allows for efficient heating and improved control over reaction conditions, particularly in extreme temperature and pressure regimes. The conclusions drawn from the research indicate that SiC vessels provide almost complete shielding from electromagnetic fields, effectively separating thermal from specific/nonthermal microwave effects on chemical reactions. This technology enables the safe use of corrosive reagents at high temperatures and pressures, which is not feasible with standard glass vessels. The chemicals used in the process include a variety of solvents with different microwave absorbtivities, such as hexane, acetonitrile (MeCN), ethanol (EtOH), and 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), as well as reagents like triethylamine trihydrofluoride (TREAT-HF) and strong aqueous bases like potassium hydroxide (KOH) for various reaction scenarios.
10.1016/j.jorganchem.2005.02.018
The research investigates how ionic liquid solvents influence ligand substitution reactions, specifically focusing on the displacement of anionic ligands by pyridine derivatives in trans-(Ph3P)2Rh(CO)NO3. The study aims to understand the effects of ionic liquids on reaction rates, mechanisms, and selectivity, particularly in the context of homogeneous catalytic processes. 1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]) plays a crucial role as a solvent medium for studying ligand substitution reactions. Specifically, it is used to investigate how ionic liquids can influence the displacement of anionic ligands by neutral molecules in the complex trans-(Ph3P)2Rh(CO)NO3. Key chemicals used include various pyridine derivatives such as 2-fluoropyridine and 2,6-difluoropyridine. The researchers found that these ionic liquids significantly promote the formation of charge-separated ligand substitution products compared to dichloromethane, with [C4mim][PF6] showing a stronger effect than [C6pyr][Tf2N]. The study concludes that ionic liquids can enhance catalytic processes where anionic ligands compete for coordination to the active site, and their weak coordinating ability makes them suitable alternatives to traditional polar organic solvents in such reactions.
10.1081/SCC-100105664
J. Howarth, P. James, and R. Ryan investigates the use of the ionic liquid [BMIM]PF6 as a solvent for the reduction of aldehydes and ketones with sodium borohydride (NaBH4). The study demonstrates that this reduction can be effectively carried out in [BMIM]PF6, and the ionic liquid can be recycled for reuse. In some cases, the product alcohols can be directly distilled from the ionic liquid, eliminating the need for classical organic solvents. The researchers tested the reduction of six common aldehydes and ketones, achieving good yields and purity of the resulting alcohols. This work highlights the potential of [BMIM]PF6 as an environmentally friendly alternative to traditional solvents in organic synthesis, particularly for reactions involving sodium borohydride.