Fukui, Kenichi (1918–1998)

Japanese industrial chemist who shared the Nobel Prize for Chemistry in 1981 with Roald Hoffmann for his work on ‘frontier orbital theory’, predicting the change in molecular orbitals (the arrangement of electrons around the nucleus; see orbital, atomic) during chemical reactions.

Fukui described a reaction involving methyl radicals as the interaction between two of the electronic orbitals of the reacting molecules. He called these frontier orbitals and discovered that the course of a chemical reaction was determined partly by the symmetry of the frontier orbitals.

The importance of his findings was initially overlooked as Fukui presented them in mathematical terms that confounded contemporaries. However, following a publication by Robert Woodward and Roald Hoffmann that outlined the rules for the conservation of orbital symmetry, scientists came to realize the importance of Fukui's theories. This led to the use of frontier orbital theory in rationalizing organic reactivity and preceded sophisticated computer calculations.

Fukui was born in the district of Nara, Japan, and studied industrial chemistry at Kyoto University. He spent World War II working in industry as a technician in the Army Fuel Laboratory, but in 1948 he returned to Kyoto University, where he obtained a PhD in engineering. Here he found his true vocation and advanced to become professor of hydrocarbon physical chemistry in 1951, a position he held until his retirement 1982. He was president of the Japanese Chemical Society 1983–84.