- Lindlar catalyst
Chembox new
Name = Lindlar catalyst
ImageFile = Lindlar_eng.png
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 ofpalladium deposited oncalcium carbonate and treated with various forms oflead . The lead additive serves to deactivate the palladium sites. A variety of "catalyst poisons" have been used includinglead acetate and lead oxide. The palladium content of the catalyst is usually 5% by weight. The catalyst is used for thehydrogenation ofalkyne s toalkene s.As described by its inventor,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] [Lindlar, H."Ein neuer Katalysator für selektive Hydrierungen"; "Helv. Chim. Acta" 1952, "35", 446-450, DOI|10.1002/hlca.19520350205.] 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 withquinoline enhances its selectivity, preventing formation ofalkane s. An example of alkyne reduction is the reduction ofphenylacetylene tostyrene .Alkyne reduction is
stereoselective , occurring viasyn addition to give thecis-alkene . [ 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] The commercialorganic synthesis ofvitamin A also involves an alkyne reduction with the Lindlar catalyst.Other heterogeneous catalysts useful for hydrogenation are
Adam's Catalyst ,Palladium Black , andRaney nickel .References
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