X-Ray Diffraction Studies of Novel Tolunitrile Adducts of Rhodium(II) Acetate and Evaluation of their Usefulness in Stereoselective Cyclopropanation Catalysis
Faculty Mentor
Cassandra Eagle
Mentor Home Department
Chemistry
Short Abstract
The objective of this research is to synthesize, characterize, and investigate the catalytic properties of p-tolunitrile and m-tolunitrile adducts of rhodium(II) acetate. Without adducts, rhodium(II) acetate possesses the ability to catalyze the formation of cyclopropanes—strained, three-carbon rings that are a defining structural feature of the group of insecticides known as pyrethrins (found naturally in chrysanthemum flowers). The rhodium(II) acetate ‘paddlewheel’ structure does not selectively catalyze the formation of the biologically active cyclopropane product, however; a mix of isomers is created that must be separated. This separation process is expensive in time and percent yield. The isolation and purification of the biologically active cyclopropane, then, is not industrially viable: with every step in the purification of the pyrethrin mixture, a significant amount of product is sacrificed. Thus, the pyrethrins in their commercial pure form are prohibitively expensive for most desired applications. Moreover, natural pyrethrins are not heat, pH, or light-stable—precluding their use in outdoor applications. Pyrethroids are more stable, synthetic versions of pyrethrins. Our goal of enhancing Rh2(OAc)4’s selectivity for the biologically active pyrethroid confirmation is realized by changing the axial adducts. We synthesized Rh2(OAc)4·2NCR where R = p-toluene or m-tolunitrile. Rh2(OAc)4·2NCR complexes have been characterized by single crystal x-ray crystallography, 1H, and 13C{1H} NMR, and the products of their use as catalysts in cyclopropanation reactions have been studied using Gas Chromatography/Mass Spectrometry.
Category
Science, Technology and Engineering
Start Date
5-4-2024 11:30 AM
End Date
5-4-2024 12:30 PM
Location
D.P. Culp Center Multicultural Center Presentation Room
X-Ray Diffraction Studies of Novel Tolunitrile Adducts of Rhodium(II) Acetate and Evaluation of their Usefulness in Stereoselective Cyclopropanation Catalysis
D.P. Culp Center Multicultural Center Presentation Room
The objective of this research is to synthesize, characterize, and investigate the catalytic properties of p-tolunitrile and m-tolunitrile adducts of rhodium(II) acetate. Without adducts, rhodium(II) acetate possesses the ability to catalyze the formation of cyclopropanes—strained, three-carbon rings that are a defining structural feature of the group of insecticides known as pyrethrins (found naturally in chrysanthemum flowers). The rhodium(II) acetate ‘paddlewheel’ structure does not selectively catalyze the formation of the biologically active cyclopropane product, however; a mix of isomers is created that must be separated. This separation process is expensive in time and percent yield. The isolation and purification of the biologically active cyclopropane, then, is not industrially viable: with every step in the purification of the pyrethrin mixture, a significant amount of product is sacrificed. Thus, the pyrethrins in their commercial pure form are prohibitively expensive for most desired applications. Moreover, natural pyrethrins are not heat, pH, or light-stable—precluding their use in outdoor applications. Pyrethroids are more stable, synthetic versions of pyrethrins. Our goal of enhancing Rh2(OAc)4’s selectivity for the biologically active pyrethroid confirmation is realized by changing the axial adducts. We synthesized Rh2(OAc)4·2NCR where R = p-toluene or m-tolunitrile. Rh2(OAc)4·2NCR complexes have been characterized by single crystal x-ray crystallography, 1H, and 13C{1H} NMR, and the products of their use as catalysts in cyclopropanation reactions have been studied using Gas Chromatography/Mass Spectrometry.