History
The Mortreux system consists of the molybdenum catalyst molybdenum hexacarbonyl Mo(CO)6 and resorcinol cocatalyst. In 1975 T.J. Katz proposed a metal carbyne and a metallacyclobutadiene as an intermediate and in 1981 R.R. Schrock characterized several metallacyclobutadiene complexes that were catalytically active.
The Schrock catalyst system tris(t-butoxy)(2,2-dimethylpropylidyne)tungsten(VI) is unreactive towards alkenes. On the other hand Fischer carbenes have no value in alkyne or alkene metathesis.
The Schrock catalyst is commercially available and is prepared by amidation of tungsten tetrachloride with lithium dimethylamide to a W2(NMe2)6 which undergoes alcoholysis by tert-butoxy groups with tert-butanol.
This alkylidyne complex undergoes a metathesis with neoheptyne to give the final product. In 2001, Fürstner reported a new molybdenum catalyst replacing alkoxide with aniline ligands.
Read more about this topic: Alkyne Metathesis
Famous quotes containing the word history:
“When the coherence of the parts of a stone, or even that composition of parts which renders it extended; when these familiar objects, I say, are so inexplicable, and contain circumstances so repugnant and contradictory; with what assurance can we decide concerning the origin of worlds, or trace their history from eternity to eternity?”
—David Hume (1711–1776)
“Man watches his history on the screen with apathy and an occasional passing flicker of horror or indignation.”
—Conor Cruise O’Brien (b. 1917)
“For a transitory enchanted moment man must have held his breath in the presence of this continent, compelled into an aesthetic contemplation he neither understood nor desired, face to face for the last time in history with something commensurate to his capacity for wonder.”
—F. Scott Fitzgerald (1896–1940)