| Significant attention has been placed on the need for alternative reaction media due to organic solvents being the major contributor to bulk chemical waste. This bulk waste is most attributed to the pharmaceutical, agricultural chemicals, electronics, and plastics industry. In the case of the pharmaceutical industry solvents represent approximately 80% of its waste. These reaction media should not only reduce the amount of organic waste produced, but also reduce energy consumption during the purification of the organic product. Among these alternative reaction media are room temperature ionic liquids, supercritical carbon dioxide, fluorous solvents, and water.; Water is the most viable choice industrially because of its low toxicity, cost, inflammability, and over all low environmental impact. My research at the University of Alabama has focused on methods to prevent or lower the amount of waste produced. Our strategy involves the synthesis and design of water-soluble metal catalysts that allow cross-coupling reactions to be carried out in either water or water/organic biphasic solvent systems. I have shown great success with both aryl and alkyl tailored phosphine ligands that contain either sulfonate or ammonium salt functionalities. I have recently turned my attention towards the synthesis of the sulfonate salt derivatives of the recently popular immidazol; 2-ylidene Arduengo-type carbenes. We are very optimistic and hopeful about the possible success of these carbenes as possible ligands in cross-coupling, since the literature has suggested that in some cases carbenes form even more active catalyst than phosphines. Along with the carbenes I have recently been collaborating with Chris Wolterman, FMC-Li, on discovering possible substitutes for the popular t-Bu3P as a ligand towards the Hartwig-Buchwald amination. Thus far, di-t-butylneopentylphosphine and t-butydineopentylphosphine has shown to produce a more reactive catalyst towards the amination of arylbromides with secondary amines, but less reactive for aryl chlorides possibly due to a decrease in the electron density necessary for the cleavage of the C-Cl bond. |
