This is where the three-dimensional chemistry comes in. "The radical in this case is derived from racemic starting material." "Specifically in this paper we solve a problem in this field, which is how to control the stereoselective addition of a radical species to an aromatic compound," Yang said. Additionally, these radicals are essentially free in another sense - they can quickly wander away from potential reactive sites.īut Yang and collaborators have a few tricks up their sleeves: metalloenzymes - naturally occurring proteins with a reactive metal center, able to generate and rein in those free radicals for selective transformations. Free radicals, once formed, do not interact tightly with the catalyst. "In general, steering free radicals towards desired stereochemistry is very difficult," Yang said. To achieve it, chemists turned to catalysts, substances that enable chemical reactions without themselves being consumed or transformed in the process, making them reusable.Īchieving this type of stereocontrol is no small feat. Thus, to precisely control the stereochemistry is a major goal of synthetic chemistry. In contrast, ( R)-carvone or "right-handed" carvone is found in caraway seeds and has a completely different smell. For example, ( S)-carvone or "left-handed" carvone is the primary ingredient that accounts for the distinctive odor of mint. The stereochemistry of organic molecules has a significant impact on their properties. To fully unlock the synthetic potential of free radicals, Yang and colleagues focus on stereochemistry - also known as 3D chemistry, which focuses on the three-dimensional orientation of atoms and molecules. We're trying to develop biocatalytic strategies to further push the boundaries of free radical chemistry." "However, imposing stereocontrol over free-radical mediated reactions has eluded the asymmetric catalysis community for decades. "Free radical chemistry is very useful for the synthesis of both bioactive small molecules and everyday polymers," said UC Santa Barbara chemistry professor Yang Yang, an author of a paper on the matter that appears in Nature Catalysis. Oxygen is in group 6 of the periodic table.In the world of synthetic chemistry, however, free radicals hold a lot of promise. the ions are negative, because they have more electrons than protonsįor elements in groups 6 and 7, the charge on the ion relates to the group number of the element in the periodic table.The outer shells of non-metal atoms gain electrons when they form ions: A sodium atom loses one electron to form a sodium ion with a charge of 1+ Forming negative ions Sodium is in group 1 of the periodic table.
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