Search results
Results from the WOW.Com Content Network
Wilkinson's catalyst (chloridotris(triphenylphosphine)rhodium(I)) is a coordination complex of rhodium with the formula [RhCl(PPh 3) 3], where 'Ph' denotes a phenyl group. It is a red-brown colored solid that is soluble in hydrocarbon solvents such as benzene, and more so in tetrahydrofuran or chlorinated solvents such as dichloromethane .
The reaction name recognizes JirÅ Tsuji, whose team first reported the use of Wilkinson's catalyst (RhCl(PPh 3) 3) for these reactions: RC(O)X + RhCl(PPh 3) 3 → RX + RhCl(CO)(PPh 3) 2 + PPh 3. Although decarbonylation can be effected by several transition metal complexes, Wilkinson's catalyst has proven the most effective. [1]
[6] [5] These reactions proceed via the intermediacy of metal acyl hydrides. An example of this is the Tsuji–Wilkinson decarbonylation reaction using Wilkinson's catalyst. (Strictly speaking, the noncatalytic version of this reaction results in the formation of a rhodium carbonyl complex rather than free carbon monoxide.)
The difference in regioselectivity is more pronounced in the hydroboration of vinylarenes with HBcat. Wilkinson's catalyst or the cation Rh(COD) 2 (in the presence of PPh 3) produces the Markovnikov product. [12] [13] The anti-Markovnikov product is produced in the absence of a catalyst. [14]
An induction period in chemical kinetics is an initial slow stage of a chemical reaction; after the induction period, the reaction accelerates. [1] Ignoring induction periods can lead to runaway reactions. In some catalytic reactions, a pre-catalyst needs to undergo a transformation to form the active catalyst, before the catalyst can take ...
Hydroacylation is a type of organic reaction in which an electron-rich [1] unsaturated hydrocarbon inserts into a formyl C-H bond. With alkenes, the product is a ketone: RCHO + CH 2 =CHR' → RC(O)CH 2 CH 2 R' With an alkyne instead, the reaction produces an α,β-unsaturated ketone. [2] The reaction requires a metal catalyst or a radical ...
Since catalysts are regenerated, catalytic cycles are usually written as a sequence of chemical reactions in the form of a loop. In such loops, the initial step entails binding of one or more reactants by the catalyst, and the final step is the release of the product and regeneration of the catalyst.
The catalyst may increase the reaction rate or selectivity, or enable the reaction at lower temperatures. This effect can be illustrated with an energy profile diagram. In the catalyzed elementary reaction, catalysts do not change the extent of a reaction: they have no effect on the chemical equilibrium of a reaction.