John E. Bercaw (born December 3, 1944)[citation needed] is an American chemist and Centennial Professor of Chemistry, Emeritus at the California Institute of Technology.

[6] His research interests are in synthetic, structural and mechanistic organotransition metal chemistry, including most recently catalysts for polymerization and trimerization of olefins and investigations of hydrocarbon hydroxylation; fundamental transformations and thermodynamics of organotransition metal chemistry; catalysts for hydrocarbon partial oxidation; catalysts for olefin trimerization and polymerization; homogeneous transformations of carbon monoxide and dihydrogen to fuels and chemicals.

This metal-catalyzed polymerization process is operated on a vast scale and produces, worldwide, over 200 billion pounds of polyolefins per year.

Bercaw’s work has led to a fundamental understanding of the detailed mechanisms of chain growth in ZN polymerizations and the factors which control syndio- and isotacticities and the degree of comonomer incorporation in copolymerizations; these variables are critical in determining the physical properties of the resultant polymers and copolymers.

For example, new and superior ethylene/alpha-olefin copolymers are now industrially produced with titanium catalysts utilizing (η5- C5Me4)SiMe2NCMe3 and related ligands devised in Bercaw’s laboratories.