Supercritical fluid technology reaction selectivity

More polymerization reactions carried out at supercritical conditions, select biomass conversion supercritical fluid technologies for hydrogen production, wider use of supercritical water oxidation processes, portfolio of self-assembly applications, a spate of opportunities in process intensification, many supercritical fluid aided materials synthesis applications, and numerous reactions for synthesis of specialty chemicals are expected for years to come. 

As mentioned earlier, physical chemistry plays a significant role in providing understanding of phenomena important to developing supercritical fluid technology for chemical synthesis applications (see Figure 3). A previous study of Diels-Alder reactions with cyclopentadiene and ethyl acrylate in our group illustrates this important role. As mentioned above, of paramount interest was the intrinsic rate of this bimolecular reaction as well as the endo to exo selectivity in scCOa this... 

Carbon dioxide, either as an expanded liquid or as a supercritical fluid, may be a viable replacement for a variety of conventional organic solvents in reaction systems. Numerous studies have shown that many reactions can be conducted in liquid or supercritical C02 (sc C02) and, in some cases, rates and selectivities can be achieved that are greater than those possible in normal liquid- or gas-phase reactions (other chapters in this book Noyori, 1999 Savage et al., 1995). Nonetheless, commercial exploitation of this technology has been limited. 

The ability of supercritical fluids (SCFs) to act as solvents has been known for well over a century [1] yet the most significant developments in the application of this technology have taken place in the last few decades. Among their most recent applications, SCFs have been employed as media for chemical reactions. As a reaction medium, the SCF may either participate directly in the reaction or simply act as a solvent for the various chemical species. The physical properties of SCFs are highly dependent on pressure and temperature which makes it possible to fine-tune the reaction environment. These characteristics are unique to SCFs and provide the potential to tune the reaction environment in order to optinuze reaction rate and selectivity. 

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