New Technologies in Organic Synthesis in Water

University Of California-Santa Barbara, Santa Barbara CA

Investigators

Abstract

The Chemical Synthesis Program of the Chemistry Division supports the research of Professor Bruce Lipshutz at the University of California at Santa Barbara. This project aims to develop more environmentally-friendly methods of making organic chemicals, specifically by switching from petroleum-based (organic) solvents to water as the medium to conduct the chemical reaction. Organic solvents are often flammable and toxic, representing a major waste stream as they may be separated from both the starting and ending products of a chemical reaction. The increased use of water as a solvent has considerable potential impact for reducing the use of organic solvents. In an example research theme, micelles (similar to soap bubbles) are used as a way to avoid the use of organic solvents in bringing compounds in close contact so that they react. In addition to the scientific research which may benefit the advanced manufacturing of many commodity chemicals such as fertilizers and pharmaceuticals, the team provides training on the principles of sustainability to high school students and teachers. These students and teachers spend their summer gaining hands-on experience in the implementation of environmentally-friendly reaction chemistries. Research being conducted under this NSF award focuses on development of new technologies in organometallic chemistry, conducted under Green Chemistry conditions. Envirionmentally-friendly reactions will be accomplished by developing palladacycle backbones that include the new ligand HandaPhos, which enables the Suzuki-Miyaura (SM) couplings at the 300 parts per million (ppm) level of catalyst loading. A new ligand recently disclosed, EvanPhos, offers new opportunities for SM couplings. Other projects of value include the development of new nickel nanoparticles that dehalogenate dihalocyclopropanes in water under very mild conditions as well as a new reductive amination protocol done in water at room temperature. Also included in this research is the discovery of a new palladium catalyst that converts Buchwald-Hartwig aminations into an environmentally friendly processes and, for the first time, allows for this chemistry to be done at the ppm level of catalyst loading. New directions also presented include using conformational control within crowded nanomicelles, rather than temperature, to maximize enantiomeric excesses in asymmetric catalysis, and the further advancement of continuous flow techniques using micellar catalysis as the reaction medium. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.