A physical organic chemist, Walling is best known for his research on the mechanisms of free radical reactions. After obtaining the Ph.D. in 1939 at Chicago with M.S. Kharasch (see portrait), he worked in industry for 12 years (DuPont, U.S. Rubber, Lever Brothers), doing research on vinyl polymerization, copolymerization and polar effects in radical reactions. With Frank R. Mayo, he published two seminal articles in Chemical Reviews, on the peroxide effect (1940) and on copolymerization (1950).
In 1952 Walling joined the Columbia University faculty where he initiated programs on the effects of high pressure on reaction rates, and on the mechanisms of various free radical reactions. Among the latter were hydroperoxide decomposition, autoxidation of Grignard reagents and the chemistry of alkoxy radicals. He showed that cis- and trans-allylic radicals retain their configurational integrity. In 1957 Walling's book "Free Radicals in Solution" was published. It became a classic and contributed to the education of a generation of chemists.
In 1969 Walling moved to the University of Utah where he remained until his retirement in 1992. During those years he assumed various professional responsibilities, as editor-in-chief of the Journal of the American Chemical Society (1975-81) and as a member and chair of the ACS Committee on Professional Training. Walling published over 200 papers. Among his awards were the Norris Award in Physical Organic Chemistry (1971) and the ACS Award in Petroleum Chemistry (1984). In 1995 the ACS published his autobiography "Fifty Years of Free Radicals".
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Source: Professor Walling