Tetrafluoro(trifluoromethyl)sulfanes Chemical Reactivity and Polar Hyrdophobicity

With the support of the Chemical Structure, Dynamics, and Mechanisms B (CSDM-B) Program in the Division of Chemistry, Professor John T. Welch of the University at Albany, will investigate a novel thermally and chemically stable functional group that may ultimately replace persistent and toxic compounds used in the preparation of pharmaceuticals and agrochemicals. Unfortunately, the problem of environmental persistence is endangering the use fluorine chemistry in new and currently marketed products for materials science, agrochemical, biochemical and medicinal chemistry is endangered by. For at least 75 years, fluorination and the introduction of fluorinated functional groups has led to significant advances in materials research, in the life sciences and in fundamental chemical investigations. Nearly 20% of pharmaceuticals and 40% of agrochemicals contain fluorine, typically in selectively fluorinated functional groups. It is increasingly apparent that undesirable environmental effects accompany these versatile substituents. Environmental persistence accompanied by bioaccumulation is of particular concern to human health. The chemically and physically robust fluorinated hypervalent sulfur compounds that will be studied are predicted to decompose in an environmentally benign manner preserving the commercial utility of fluorination and fluorinated functionality. These investigations may enable economic competitiveness in the global marketplace that requires environmentally benign replacement groups such as the structures under investigation. Pursuit of this national interest requires the training of research students in the handling of extraordinarily reactive reagents such as bromine trifluoride, chlorine fluoride or fluorine, reagents essential to fluorochemical research. Seventh through twelfth grade students from historically underrepresented groups and economically disadvantaged backgrounds will be engaged in mentored laboratory research, and in collaborative, task-oriented learning to understand the importance of chemical literacy in community activism. The proposed research program will help sustain our ability to train students in this crucial area of chemical technology and research.

The electronic interactions and the steric demand of the trifluoromethyl tetrafluorosulfanyl (CF3SF4) group can control reactivity and selectivity CF3SF4-containing reactants. This novel substituent is predicted to have ideal parameters to exhibit the sort of polar hydrophobicity attributes that make it useful for the functionalization of agents designed for protein binding as tools for chemical biology or as candidates for medicinal chemistry. But there are few synthetic, mechanistic and property-related studies surrounding this interesting functional group. The polar and electronic effects of CF3SF4-group substitution on the stereoselectivity of the parent CF3SF4-methyl carbene will be investigated. As rearrangement of carbene insertion products often involve radical intermediates, electrolytic decarboxylation will be used to form CF3SF4-substituted methyl radicals for comparative reaction studies. The influence of the of the CF3SF4 group on reactions will be compared and contrasted with the effect of the trifluoromethyl group. The experimentally derived results will be used to validate the computational predictions of the reactivity of the CF3SF4 -substituted reactants. The CF3SF4-containing products will be tested for susceptibility to benign degradation processes by determining aqueous photostability on irradiation at wavelengths greater than 290 nm. Susceptibility to biodegradation will be determined by establishing the ability of members of the genus Pseudomonas and Streptomyces to grow on CF3SF4-containing products.

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.