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The hydrogen atoms occupy interstitial sites in palladium hydride. The H–H bond in H 2 is cleaved. The ratio in which H is absorbed on Pd is defined by = [] [].When Pd is brought into a H 2 environment with a pressure of 1 atm, the resulting concentration of H reaches x ≈ 0.7.
The palladium-hydrogen electrode (abbreviation: Pd/H 2) is one of the common reference electrodes used in electrochemical study. [1] Most of its characteristics are similar to the standard hydrogen electrode (with platinum). But palladium has one significant feature—the capability to absorb (dissolve into itself) molecular hydrogen. [2] [3]
Hydrogenation is a chemical reaction between molecular hydrogen (H 2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic compounds .
A Lindlar catalyst is a heterogeneous catalyst consisting of palladium deposited on calcium carbonate or barium sulfate then poisoned with various forms of lead or sulfur. It is used for the hydrogenation of alkynes to alkenes (i.e. without further reduction into alkanes). It is named after its inventor Herbert Lindlar, who discovered it in 1952.
Palladium compounds owe their reactivity to the ease of interconversion between Pd(0) and palladium(II) intermediates. There is no conclusive evidence however for the involvement of Pd(II) to Pd(IV) conversions in palladium mediated organometallic reactions. [9] One reaction invoking such mechanism was described in 2000 and concerned a Heck ...
Palladium on carbon is a common catalyst for hydrogenolysis. Such reactions are helpful in deprotection strategies. Such reactions are helpful in deprotection strategies. Particularly common substrates for hydrogenolysis are benzyl ethers : [ 5 ]
The catalyst is also used for the hydrogenolysis of phenyl phosphate esters, a reaction that does not occur with palladium catalysts. The pH of the solvent significantly affects the reaction course, and reactions of the catalyst are often enhanced by conducting the reduction in neat acetic acid, or solutions of acetic acid in other solvents.
The reaction conditions and purifications could be simplified by using excess palladium(II) acetate without benzoquinone. [3] [4] Since the reaction typically employs near-stoichiometric amounts of palladium and is therefore often considered too expensive for industrial usage, some progress has been made in the development of catalytic variants.