German chemist who in 1963 shared the Nobel Prize for Chemistry with
Giulio Natta for research that greatly improved the quality of plastics. 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.
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