Development of Novel Radical Chemistry Utilizing the Heavy Group 15 Heteroatom Compounds

点击翻译按钮获取中文摘要

Synthetic radical chemistry of group 16 and 17 heteroatom compounds, such as organoselenides, tellurides, bromides, and iodides, has been the subject of intensive research over the past several decades because of their ability to generate carbon-centered radicals under mild conditions. In contrast, the synthetic radical chemistry of group 15 heteroatom compounds is virtually unknown, and their synthetic applications are totally unexplored. This research is aimed to clarify the synthetic utilities of heavier group 15 heteroatom compounds, such as organostibines and organobismuthines, under radical conditions for the precise synthesis of living polymers and small organic molecules.Several new organostibine and bismuthine chain transfer agents for living radical polymerization have been designed and synthesized. They promoted highly controlled living radical polymerization of various vinyl monomers, such as styrene derivatives, (meth)acrylate derivatives, and N-vinylamides, giving living … More polymers with controlled molecular weights as predicted by the ratio of monomer/chain transfer agent and very narrow molecular weight distributions. The high versatility for monomer families and high compatibility to polar functional groups make these compounds highly useful for the synthesis of structurally well defined macromolecules with dense functionalitics. The observed high control has been attributed to the high reactivity of these heteroatom compounds towards the homolytic substitution reaction (the degenerative chain transfer reaction) with polymer end radicals; the fast reaction makes it possible to elongate all of the polymer chains with similar chain lengths. The rate constant for the homolytic substitution reaction is fastest in organobismuthines followed by organostibines, organotelluriums, and then organoiodines, and this order is consistent with the level of control of living radical polymerization using these heteroatom compounds.Reactivities of distibines and thiobismuthines have been also examined. They have also shown excellent reactivity towards the homolytic substitution reaction with carbon centered radicals. Due to the high reactivity, they have served as cocatalysts in the living radical polymerization to increase the control of molecular weight distribution and to synthesize polymers with ultrahigh molecular weights under controlled manner.These results clearly demonstes that heavier group 15 heteroatom compounds are excellent precursors for carbon centered radicals and also possess considerable synthetic utilities in radical reactions. Less