Lindlar catalyst 1997096 162224971 2007-10-04T12:17:16Z Rifleman 82 1255637 /* External links */ duplicated {{Chembox new | Name = Lindlar catalyst | ImageFile = Lindlar_eng.png <!-- | ImageSize = 150px --> | ImageName = | OtherNames = Palladium on calcium carbonate, poisoned | Section1 = {{Chembox Identifiers | CASNo = 7440-05-3 | RTECS = }} | Section2 = {{Chembox Properties | Formula = not a compound | Appearance = Gray powder }} | Section7 = {{Chembox Hazards | ExternalMSDS = [http://ptcl.chem.ox.ac.uk/MSDS/PA/palladium(poisoned).html External MSDS] | MainHazards = none | RPhrases = {{R20}} {{R33}} {{R36}} {{R37}} {{R38}} | SPhrases = {{S22}} {{S27}} {{S36}} {{S37}} {{S39}} }} | Section8 = {{Chembox Related | OtherCpds = [[Palladium on carbon]] }} }} A '''Lindlar catalyst''' is a [[heterogeneous]] [[catalyst]] that consists of [[palladium]] deposited on [[calcium carbonate]] and treated with various forms of [[lead]]. The lead additive serves to [[catalyst poisoning|deactivate]] the palladium sites. A variety of "catalyst poisons" have been used including [[lead acetate]] and [[Lead(II) oxide|lead oxide]]. The palladium content of the catalyst is usually 5% by weight. The catalyst is used for the [[hydrogenation]] of [[alkyne]]s to [[alkene]]s. As described by its inventor,<ref name=Lindlar>Lindlar, H.; Dubuis, R. "Palladium Catalyst for Partial Reduction of Acetylenes" Organic Syntheses, Collected Volume 5, p.880 (1973).http://www.orgsyn.org/orgsyn/pdfs/CV5P0880.pdf</ref><ref>Lindlar, H. "Ein neuer Katalysator für selektive Hydrierungen"; ''Helv. Chim. Acta'' 1952, ''35'', 446-450, {{DOI|10.1002/hlca.19520350205}}.</ref> the catalyst is prepared by reduction of [[palladium chloride]] in a slurry of calcium carbonate followed by adding lead acetate. By this approach, one obtains a catalyst with a large surface area. Further deactivation of the catalyst with [[quinoline]] enhances its selectivity, preventing formation of [[alkane]]s. An example of alkyne reduction is the reduction of [[phenylacetylene]] to [[styrene]].<ref name=Lindlar/> Alkyne reduction is [[stereoselective]], occurring via [[syn addition]] to give the [[cis-alkene]].<ref> Overman, L. E.; Brown, M. J.; McCann, S. F. "(Z)-4-(Trimethylsilyl)-3-Buten-1-ol" Organic Syntheses, Collected Volume 8, p.609 (1993). http://www.orgsyn.org/orgsyn/pdfs/CV8P0609.pdf</ref> The commercial [[organic synthesis]] of [[vitamin A]] also involves an alkyne reduction with the Lindlar catalyst. Other heterogeneous catalysts useful for hydrogenation are [[Adam's Catalyst]], [[Palladium Black]], and [[Raney nickel]]. ==References== <references/> [[Category:Catalysts]] [[Category:Palladium compounds]] [[de:Lindlar-Katalysator]] [[fr:Catalyseur de Lindlar]] [[ja:リンドラー触媒]]