Lindlar catalyst
1997096
162224971
2007-10-04T12:17:16Z
Rifleman 82
1255637
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{{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 =
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| Section2 = {{Chembox Properties
| Formula = not a compound
| Appearance = Gray powder
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| 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]]