Karl Ziegler

Karl Ziegler
(1898 - 1973)

German chemist who in 1963 shared the Nobel Prize for Chemistry with Giulio Natta for research that greatly improved the quality of plastics.
After receiving his doctorate (1923) from the University of Marburg, Ziegler held academic appointments at the universities of Frankfurt am Main, Heidelberg, and Halle. In 1943 he became director of the Kaiser Wilhelm (later Max Planck) Institute for Coal Research at Mulheim an der Ruhr.

Ziegler was the first to explain the reactions involved in the synthesis of rubber (c. 1928). His researches with lithium in organic chemistry produced compounds more reactive than the Grignard reagents on which they were modeled. His work on cyclic carbon compounds found use in synthesizing the aroma of musk for perfumes.

After World War II he concentrated on organoaluminum compounds. Ziegler's most important discovery was made in 1953. He and a student, E. Holzkamp, set out to repeat a preparation of higher aluminum alkyls by heating ethylene and aluminum triethyl; unexpectedly they obtained a complete conversion of the ethylene monomer (CH2 = CH2) to the dimer, 1-butene (CH3CH2CH = CH2). The explanation was found in the presence of a trace of colloidal nickel derived from the catalyst used previously in the autoclave for hydrogenation experiments. This led to the discovery that substances made by mixing organometallic compounds with compounds of certain heavy metals permitted the fast polymerization of ethylene at atmospheric pressure to a linear polymer of high molecular weight having valuable plastic properties (other processes used high pressure and produced a partly branched polymer). The catalyst derived from aluminum alkyl and titanium tetrachloride proved especially useful. It formed the basis of nearly all later developments in the production of long-chain polymers of hydrocarbons from such olefins as ethylene and butadiene; the resulting products came into widespread use as plastics, fibres, rubbers, and films.