Polar ionic media and stabilized charged species in organic synthesis: Ionic liquids derived from a biorenewable source, D-fructose, as a possible alternative to conventional organic reaction solvents

In our quest for synthetic materials, the preparation of these materials should be as ideal as possible starting with inexpensive materials, simple reaction methods, easy purification, high yields, short reaction sequences, and environmentally compatible or "green." This concept of greenness implies not only that reagents and solvents must be non-toxic and not highly volatile, explosive, or flammable, but also that waste materials must be minimized. Conventional organic solvents are high on the list of damaging chemicals for two simple reasons: (i) huge amounts are used and (ii) they are usually volatile and hence difficult to contain. In the recent past, efforts have been geared towards the search for alternative solvents, including supercritical fluids, water, fluorinated solvents, and room temperature ionic liquids (RTILs). Although, all of these categories have their advantages and disadvantages, this last group---the room temperature ionic liquids (RTILs)---has several particularly attractive features, including a lack of volatility and large liquid range (up to 400°C).; One problem with room temperature ionic liquids (RTILs) is their expense. In an effort to overcome this obstacle, RTILs derived from a biorenewable resource, D-fructose, have been developed. The new, functionalised RTILs have been synthesized and their use as organic reaction media is presented. These new ionic liquids portray variable characteristics based on the different anions investigated such as thermal stability, solubility, and viscosity. The fructose derived RTILs have afforded results for the Heck reaction comparable to the conventional RTILs in terms of reaction rates and conversions as well as catalyst recycling ability. The impact of the hydroxymethylene functionality on the rate of this reaction was studied and the results are in accordance with those expected based on the coordination effect on the palladium metal. The effect of residual halide impurities in the ionic liquids was also discovered, in which it was noted that iodide or bromide significantly accelerated the rate of the Heck reaction.; Another area of exploration was the use of these new ionic liquids as support materials, an area not available to conventional ionic liquids. These RTIL supports can be used for either the supported, solution-phase synthesis of small molecules or for recyclable supported catalysts/reagents. A specific example of the former is the use of a tethered acrylate in Diels-Alder reactions, while the latter area includes the development and use of tethered hypervalent iodine reagents such as supported Koser's salt. By making use of the anion to tune the physical properties of these compounds, supports have been prepared that can be more readily recovered and recycled. (Abstract shortened by UMI.)...