ACS Award For Creative Work In Fluorine Chemistry

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In the early years of fluorine chemistry, researchers often carried out fluorination reactions by using highly reactive elemental fluorine gas, toxic sulfur tetrafluoride gas, and corrosive anhydrous hydrogen fluoride. These brute-force reagents typically require specialized reaction vessels and training. But that was all the chemists had.

For many fluorine chemists, a goal became to develop fluorinating reagents that could be used without any special conditions. A number of these easily handled reagents and methods have now emerged, and they offer a kinder, gentler approach that is revolutionizing fluorine chemistry, especially in the preparation of pharmaceuticals and agrochemicals.

One of the most prolific developers of these fluorinating reagents has been Teruo Umemoto, who first became known in the 1980s for his fluoroalkyl phenyliodonium triflate, or FITS, reagents for adding perfluoroalkyl groups to organic molecules.

Later he developed popular dibenzo(trifluoromethyl) sulfonium salts for trifluoromethylations, often collectively referred to as Umemoto’s reagents. Meanwhile, he also developed N-fluoropyridinium salts for directly adding fluorine to organic molecules.

Among his recent projects, Umemoto developed a new deoxofluorination reagent, called Fluolead, a phenylsulfur trifluoride compound that strips oxygen from carbonyl compounds to make fluoroalkyl derivatives.

“If Umemoto had developed only one of the various classes of reagents, then he would have made an enduring contribution to fluorine chemistry,” says David O’Hagan, a chemistry professor at the University of St. Andrews, in Scotland, and former recipient of this award. “However, emerging every five years or so with an entirely new contribution and approach to fluorination technology makes him one of the most innovative scientists in fluorine chemistry.”

Take Fluolead, for example. This phenyl­sulfur trifluoride compound is an alternative to diethylaminosulfur trifluoride (DAST), which itself is a popular alternative to SF₄ for deoxofluorinations. As a liquid, DAST is easier to handle than SF₄ gas, but it’s still highly reactive and thermally sensitive. Fluolead is a stable, crystalline solid that doesn’t fume in air, doesn’t immediately react with water, and can be safely handled well above room temperature.

While developing Fluolead, Umemoto also came up with the first practical industrial process for producing arylsulfur pentafluorides (ArSF₅). The SF₅ group is more lipophilic and electronegative than a CF₃ group—making it an even more attractive functional group in pharmaceutical and agrochemical arenas than CF₃. In fact, SF₅ has been labeled the “substituent of the future” by organofluorine chemists.

Umemoto, 65, a native of Japan, studied chemistry at Okayama University, where he received a B.S. degree in 1971. For his graduate studies, Umemoto received an M.S. in chemistry in 1973 and a doctorate in organic chemistry in 1976, both from Osaka University.

In his early professional career, Umemoto worked as a researcher in the Sagami Chemical Research Center, where he kindled his interest in fluorine chemistry as he rose to the rank of chief researcher. In 1990, Umemoto moved to Daikin Industries to continue his fluorine work as a research manager. In 1998, he transitioned to the U.S., where he started Denver-based IM&T Research. Umemoto served as IM&T’s president until 2011, when UBE America took over the business.

An industrialist at heart, Umemoto has more than 140 patent applications to his credit, in addition to nearly 70 research papers. Among his awards, Umemoto received a 1983 Progress Award for young chemists from the Chemical Society of Japan and a ­Certificate of Noticed Invention from Japan’s Science & Technology Agency in 1988.

Umemoto will present his award address before the Division of Fluorine Chemistry during the fall ACS national meeting in San Francisco.