Search results
Results From The WOW.Com Content Network
In organic chemistry, ethenolysis is a chemical process in which internal olefins are degraded using ethylene (H 2 C=CH 2) as the reagent. The reaction is an example of cross metathesis . The utility of the reaction is driven by the low cost of ethylene as a reagent and its selectivity.
In organic chemistry, 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. [1] [2] Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative ...
In the 1960s, ruthenium trichloride was found to catalyze olefin metathesis. Processes were commercialized based on these discoveries. These ill-defined but highly active homogeneous catalysts remain in industrial use. [6] The first well-defined ruthenium catalyst was reported in 1992. [7] It was prepared from RuCl 2 (PPh 3) 4 and ...
The mechanism of homogeneous ring-opening metathesis polymerization is well-studied. It is similar to any olefin metathesis reaction. Initiation occurs by forming an open coordination site on the catalyst. Propagation happens via a metallacycle intermediate formed after a 2+2 cycloaddition. When using a G3 catalyst, 2+2 cycloaddition is the ...
The metal-mediated processes include a carbonyl-olefination and an olefin–olefin metathesis event. There are two general mechanistic schemes to perform this overall transformation: one, reaction of a [M=CHR 1] reagent with an alkene to generate a new metal alkylidene, which then couples with a carbonyl group to form the desired substituted alkene and an inactive [M=O] species (type A); two ...
Olefin metathesis is a formal exchange of the alkylidene fragments in two alkenes. It is a catalytic reaction with carbene , or more accurately, transition metal carbene complex intermediates. In this example ( ethenolysis , a pair of vinyl compounds form a new symmetrical alkene with expulsion of ethylene .
An enyne metathesis is an organic reaction taking place between an alkyne and an alkene with a metal carbene catalyst forming a butadiene. This reaction is a variation of olefin metathesis. [1] The general scheme is given by scheme 1: When the reaction is intramolecular (in an enyne) it is called ring-closing enyne metathesis or RCEYM (scheme 2):
The likely cause for metathesis in the word "hospital" is that the result resembles a common word pattern familiar to Arabic speakers (namely a Form X verbal noun). Perhaps the clearest example of metathesis in Egyptian Arabic is the modern name of the city of Alexandria : ( Al- ) Iskandariya ( الإسكندرية ).