A Lindlar catalyst is a palladium heterogeneous catalyst on calcium carbonate poisoned or deactivated or conditioned by lead acetate. or Pd - CaCO₃ - Pb (CAS 7440-05-3). In another Lindlar system the palladium is deactivated by lead oxide. The load of palladium is usually 5%. The catalyst is used in alkyne reduction. General Name, Symbol, Number palladium, Pd, 46 Chemical series transition metals Group, Period, Block 10, 5, d Appearance silvery white metallic Atomic mass 106. ... This page is a candidate to be moved to Wiktionary. ... A catalyst (Greek: καταλύτης, catalytis) is a substance that accelerates the rate of a chemical reaction, at some temperature, but without itself being transformed or consumed by the reaction (see also catalysis). ... Calcium carbonate is a chemical compound, with chemical formula CaCO3. ... Lead acetate (Trihydrate Pb(CH3COO)2·3H2O) is a white crystalline substance made by dissolving lead in acetic acid. ... CAS stands for: calibrated airspeed, the airspeed shown by an airspeed indicator, free from instrument error. ... Litharge is a yellow monoxide of lead created by heating lead in air. ...

The catalyst is prepared by reduction of palladium chloride in the presence of a slurry of calcium carbonate followed by adding lead acetate. By grafting palladium in this way to a solid substrate a large catalytically active surface area is obtained. The Lindlar catalyst is effective with hydrogen in the organic reduction of alkynes to alkenes. Deactivation of the catalyst with quinoline makes the catalyst very selective and the hydrogenation is not carried through to the alkane. Alkyne reduction is stereoselective with syn addition to the cis-alkene. The reason for this is that one face of the triple bond is shielded by the catalyst surface restricting access for the hydrogen molecule to the other side. An example of alkyne reduction is the reduction of phenylacetylene to styrene. The commercial organic synthesis of vitamin A also involves an alkyne reduction with the Lindlar catalyst. Palladium(II) chloride, also known as palladium dichloride, is a common starting material in palladium chemistry. ... Lead acetate (Trihydrate Pb(CH3COO)2·3H2O) is a white crystalline substance made by dissolving lead in acetic acid. ... General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ... Organic reductions or organic oxidations or organic redox reactions are redox reactions that take place with organic compounds. ... Alkynes are hydrocarbons that have at least one triple bond between carbon atoms. ... An alkene is an unsaturated hydrocarbon containing at least one carbon-carbon double bond. ... Quinoline, also known as 1-azanaphthalene, 1-benzazine, or benzo[b]pyridine, is a heterocyclic aromatic organic compound. ... An alkane in organic chemistry is a saturated hydrocarbon, that is, a hydrocarbon in which the molecule has the maximum possible number of hydrogen atoms and so has no double bonds. ... In chemistry, a stereoselective chemical reaction yields a mixture of stereoisomers from a single reactant where it is observed that the formation of one stereoisomer is favoured over the other. ... Styrene (also vinyl benzene, ethenylbenzene, phenethylene, cinnamene, diarex HF 77, styrolene, styrol, styropol) is an organic compound which is an aromatic hydrocarbon having the chemical formula C8H8. ... Organic synthesis is the construction of organic molecules via chemical processes. ... Retinol, the dietary form of vitamin A, is a fat-soluble, antioxidant vitamin important in vision and bone growth. ...

Other heterogeneous hydrogenation catalysts are Adam's Catalyst, Palladium Black and Raney nickel . Homogeneous catalysts include Wilkinson's catalyst. Named reagent representing platinum(IV) oxide, PtO2. ... Wilkinsons catalyst 1 is the common name for chlorotris(triphenylphosphine)rhodium(I), named after the late organometallic chemist and 1973 Nobel Laureate, Sir Geoffrey Wilkinson. ...

External links

• http://ptcl.chem.ox.ac.uk/MSDS/PA/palladium(poisoned).html

References

• Lindlar, H.; Helv. Chim. Acta 1952, 35, 446.
• Palladium catalyst for the partial reduction of acetylenes H. Lindlar and R. Dubuis Organic Syntheses, Coll. Vol. 5, p.880; Vol. 46, p.89 Article