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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 ...
Often, however, cross-coupling refers to a metal-catalyzed reaction of a nucleophilic partner with an electrophilic partner. Mechanism proposed for Kumada coupling (L = Ligand , Ar = Aryl ). In such cases, the mechanism generally involves reductive elimination of R-R' from L n MR(R') (L = spectator ligand ).
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 .
The 2-butenes are then subjected to metathesis with ethylene. Rhenium- and molybdenum-containing heterogeneous catalysis are used. Nowadays, only the "reverse" reaction is practiced, i.e., the conversion of ethylene and 2-butene to propylene: [2] CH 2 =CH 2 + CH 3 CH=CHCH 3 → 2 CH 2 =CHCH 3
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 ...
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. It produces compounds with terminal alkene functional groups (α-olefins), which are more amenable to other reactions such as polymerization and hydroformylation. The general reaction equation is:
The Shell higher olefin process (SHOP) is a chemical process for the production of linear alpha olefins via ethylene oligomerization and olefin metathesis invented and exploited by Shell plc. [1] The olefin products are converted to fatty aldehydes and then to fatty alcohols , which are precursors to plasticizers and detergents .
Corey–Winter olefin synthesis; Corey–Winter reaction; Cornforth rearrangement; Coupling reaction; Crabbé reaction; Craig method; Cram's rule of asymmetric induction; Creighton process; Criegee reaction; Criegee rearrangement; Cross metathesis; Crum Brown–Gibson rule; Curtius degradation; Curtius rearrangement, Curtius reaction ...