Knowles, William S (1917- )

US chemist who was awarded the Nobel Prize for Chemistry in 2001, shared with Japanese chemist Ryoji Noyori and US chemist K Barry Sharpless, for his development of chiral catalysts (see chirality) and their use in hydrogenation reactions.

In 1968, Knowles was the first scientist to discover a method to synthesize the desired form of a chiral compound in a hydrogenation reaction. He noticed that certain substances containing transition metals could be used to catalyse synthetic reactions in order to produce one chiral form in preference to the other. These chiral catalysts also had the advantage of speeding up the chemical reaction, so that compounds were synthesized at a faster rate. Knowles developed his techniques until he was able to synthesize the preferred form of the amino acid L-dopa, a drug used in the treatment of Parkinson's disease. As well as being used in the development of new drugs, chiral catalysts have also found applications in the synthesis of flavourings, sweeteners, and insecticides.

Knowles received his PhD from Columbia University, New York, in 1942, after which he joined the Monsanto chemical company, where he worked until his retirement in 1986.