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Jacobsen's catalysts R = Alkyl, O-alkyl, O-trialkyl Best Jacobsen catalyst: R = t Bu Katsuki's catalysts R 1 = Aryl, substituted aryl R 2 = Aryl, Alkyl. The Jacobsen epoxidation, sometimes also referred to as Jacobsen-Katsuki epoxidation is a chemical reaction which allows enantioselective epoxidation of unfunctionalized alkyl- and aryl- substituted alkenes.
The double bond of an alpha olefin is between the #1 and #2 (IUPAC) or α and β (common) carbon atoms. In organic chemistry , terminal alkenes ( alpha-olefins , α-olefins , or 1-alkenes ) are a family of organic compounds which are alkenes (also known as olefins) with a chemical formula C x H 2 x , distinguished by having a double bond at the ...
Alkenes react with percarboxylic acids and even hydrogen peroxide to yield epoxides: RCH=CH 2 + RCO 3 H → RCHOCH 2 + RCO 2 H. For ethylene, the epoxidation is conducted on a very large scale industrially using oxygen in the presence of silver-based catalysts: C 2 H 4 + 1/ 2 O 2 → C 2 H 4 O. Alkenes react with ozone, leading to the scission ...
Cyclization reactions, or intramolecular addition reactions, can be used to form cycloalkenes. These reactions primarily form cyclopentenones, a cycloalkene that contains two functional groups: the cyclopentene and a ketone group. [12] However, other cycloalkenes, such as Cyclooctatetraene, can be formed as a result of this reaction. [11]
The less hindered faces of the enone and alkene react. [9] Intramolecular enone–alkene cycloaddition may give either "bent" or "straight" products depending on the reaction regioselectivity. When the tether between the enone and alkene is two atoms long, bent products predominate due to the rapid formation of five-membered rings. [10]
The model is named after Michael J. S. Dewar, [1] Joseph Chatt and L. A. Duncanson. [2] [3] The alkene donates electron density into a π-acid metal d-orbital from a σ-symmetry bonding orbital between the carbon atoms. The metal donates electrons back from a (different) filled d-orbital into the empty π * antibonding orbital. Both of these ...
The reverse reaction of RCM, ring-opening metathesis, can likewise be favored by a large excess of an alpha-olefin, often styrene. Ring-opening metathesis usually involves a strained alkene (often a norbornene) and the release of ring strain drives the reaction. Ring-closing metathesis, conversely, usually involves the formation of a five- or ...
The barrier for the rotation of the alkene about the M-centroid vector is a measure of the strength of the M-alkene pi-bond. Low symmetry complexes are suitable for analysis of these rotational barriers associated with the metal-ethene bond.In Cp Rh(C 2 H 4 )(C 2 F 4 ), the ethene ligand is observed to rotate with a barrier near 12 kcal/mol but ...