Rather, it builds a chain by clipping a double bond in half and attaching each side to one terminus of another double bond. The important feature is that the resultant polymer retains the unsaturation present in the original monomers. Metathesis has been most widely carried out on olefins. The active species in the process is a metal carbene.
Schrock of Massachusetts Institute of Technology immediately come to mind at the mention of olefin metathesis. However, the advent of olefin metathesis featured many industrial researchers, who, while working at major U.
It also involved several academic and French Petroleum Institute chemists, who helped establish the role of metal carbenes in the reaction. Olefin metathesis was first observed in the s by industrial chemists. InHerbert S. Eleuterio, at DuPont's petrochemicals department, in Wilmington, Del.
Analysis showed that the output gas was a mixture of propylene, ethylene, and 1-butene. Chemists at other petrochemical companies were getting similar baffling results.
Peters and Bernard L. Evering recorded in U. Patent 2,, assigned in to Standard Oil Co. InRobert L. Banks and Grant C. Bailey, of Phillips Petroleum, Bartlesville, Okla. Like magic, the chemistry was spewing products that could not be explained by the reactions of olefins known at the time.
The unexpected products are due to cleavage and reformation of the olefins' double bonds. One carbon of the double bond of one olefin, along with everything attached to it, exchanges place with one carbon of the double bond of the other olefin, along with everything attached to it.
The Goodyear researchers named the reaction "olefin metathesis" [Tetrahedron Lett. At about the same time, Johannes C. Mol and others at the University of Amsterdam, in the Netherlands, independently reached the same conclusion with propylene and carbonlabeled propylene in the presence of a heterogeneous catalyst [Chem.
According to a once-popular hypothesis, which was favored by Calderon and is sometimes referred to as the conventional mechanism, a cyclobutane intermediate complexed to the metal is formed [J.
However, olefin metathesis forms no cyclobutanes, and putting cyclobutanes into olefin metathesis systems does not produce alkenes. Thus inRoland Pettit, then a chemistry professor at the University of Texas, Austin, proposed a tetramethylene complex, in which four methylene units are bonded to a central metal atom [J.
In the late s, Grubbs was a postdoc at Stanford University, where his interests in organometallic chemistry, catalysis, and reaction mechanisms converged.
He first heard of olefin metathesis at a seminar there. In an attempt to explain olefin metathesis, Grubbs--who by then had moved to Michigan State University, East Lansing--proposed that the redistribution of groups around the double bonds was due to a rearranging metallacyclopentane intermediate [J.
Later, he suggested that one mode of rearrangement could lead to formation of a cyclobutane complexed to a metal carbene [Inorg. These proposals were incorrect. Had people been aware of work by French chemists published in the early s, some of these ideas might not have come up.The first compounds, however, were not productive in olefin metathesis; the metallacyclobutanes rearranged before they could form a new olefin.
Schrock's lab prepared and characterized many new tantalum, as well as niobium, complexes and tested them in olefin metathesis. Eleuterio's discovery of olefin metathesis is cited as a compelling example of a scientific development originating in industry, subsequently being nurtured by academia, and returning to industry in commercially viable form.
Early life and education Eleuterio was born in New Bedford, Massachusetts, to parents of Portuguese descent.
Olefin Metathesis Catalysts for the Synthesis of Molecules and Materials December 8, Stockholm, Sweden. New Polyethylene Ni + n CH 2=CH 2 AlEt 3 only!
Discovery of a New Reaction Zieg ler catalyst TiCl 4/Al R3 Pol ym er c onta inin g unsaturatio n-unex pe cted fo r an addi tion p oly mer n Tru e tt, et al,J. Am.
Che m. Herbert S. Eleuterio (born November 23, ) is an American industrial chemist noted for technical contributions to catalysis, polymerization, industrial research management, and science education.
In particular, he discovered the olefin metathesis reaction and several novel leslutinsduphoenix.com: Lavoisier Medal for Technical Achievement.
Herbert S. Eleuterio (born November 23, ) is an American industrial chemist noted for technical contributions to catalysis, polymerization, industrial research management, and science education. In particular, he discovered the olefin metathesis reaction and several novel leslutinsduphoenix.comutions: DuPont Co., National University of Singapore.
Olefin metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the scission and regeneration of carbon-carbon double bonds.   Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative organic reactions.