Christopher P. Junk

Physical and chemical absorptions of carbon dioxide in room-temperature ionic liquids.

Gaseous solubilities of carbon dioxide (CO2) in 18 room-temperature ionic liquids (RTILs) have been measured at an isothermal condition (about 298 K) using a gravimetric microbalance. The observed pressure-temperature-composition (PTx) data have been analyzed by use of an equation-of-state (EOS) model, which has been successfully applied for our previous works. Henrys law constants have been obtained from the observed (PTx) data directly and/or from the EOS correlation. Ten RTILs among the present ionic liquids results in the physical absorption, and eight RTILs show the chemical absorption. The classification of whether the absorption is the physical or chemical type is based on the excess Gibbs and enthalpy functions as well as the magnitude of the Henrys constant. In the chemical absorption cases, the ideal association model has been applied in order to interpret those excess thermodynamic functions. Then, two types of the chemical associations (AB and AB2, where A is CO2 and B is RTIL) have been observed with the heat of complex formations of about -11 (for AB) and from -27 to -37 (for AB2) kJ x mol(-1), respectively.

Synthesis and applications of superacids. 1,1,2,2-Tetrafluoroethanesulfonic acid, supported on silica

In this paper we focus on the synthesis and use of superacids, in particular 1,1,2,2-tetrafluoroethanesulfonic acid(TFESA), and describe how these can be optimized for reactions of key industrial importance. One area of considerable interest is the field of superacid catalysis and, specifically, the development of safer and more cost-effective acid catalysts. We report a new simplified route for preparation of these acids, making these more readily available and opening up a large number of opportunities. Partially fluorinated superacids offer several advantages over the acids commonly used in catalysis (sulfuric, hydrofluoric acid and aluminium chloride): lower loadings, lower reaction temperatures (leading to increased selectivity), fewer by-products, shorter reaction times and higher throughput. TFESA and its longer chain analogs are much less volatile than triflic acid (CF3SO3H). We tested these superacids in several processes (aromatic alkylation, acylation of arenes, isomerization, oligomerization and the Fries rearrangement). These materials are excellent acid catalysts, comparable to triflic acid, and yet easier to handle. We have also prepared supported versions of these catalysts and introduced the ability to recycle.

Catalytic reactions using superacids in new types of ionic liquids

We will describe the use of superacids, in particular 1,1,2,2-tetrafluoroethanesulfonic acid (TFESA) and 1,1,2,3,3,3-hexafluoropropanesulfonic acid (HFPSA) in the presence of ionic liquids for improved chemical processing for a range of industrially important chemical reactions. In a number of cases the reaction mixture starts as a single phase, allowing for high reactivity, then separates into two phases upon completion of the reaction. This allows for ease of product separation P. T. Anastas and T. C. Williamson, Green Chemistry: Frontiers in Benign Chemical Syntheses and Processes, Oxford University Press, 1998.