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1、AppliedCatalysisA:General226(2002)319322LetterHydrogenationofpyrrolederivativesPartV.PoisoningeffectofnitrogenonpreciousmetaloncarboncatalystsLászlóHegedu˝sa,∗,TiborMáthébaDepartmentofOrganicChemicalTechnology,BudapestUniversityofTechnologyandEconomics,H-1111Bu
2、dapest,HungarybResearchGroupforOrganicChemicalTechnology,HungarianAcademyofSciences,BudapestUniversityofTechnologyandEconomics,H-1111Budapest,HungaryReceived12April2001;receivedinrevisedform14September2001;accepted25September2001AbstractPoisoningofdifferentprec
3、iousmetalsoncarboncatalysts(Pd/C,Ru/CandRh/C)wasobservedinthehydrogenationofsomepyrrolederivatives,undermildreactionconditions,innon-acidicmedium.Inallreductions,thecatalystswerepoisonedbythehydrogenatedproducts(pyrrolidines)morestronglythanbythereactants(pyrro
4、les).Acomparisonconcerningpoisonsensitivityofthecatalyticmetalswasalsomade.©2002ElsevierScienceB.V.Allrightsreserved.Keywords:Hydrogenation;Poisoning;Palladium;Ruthenium;Rhodium;Pyrrolidines;PyrrolesIthaslongbeenknownthatcompoundscontain-(1a–c)tothecorrespondin
5、gpyrrolidines(2a–c),whichingbasicnitrogenhaveinhibitingeffectsontheareimportantandvaluablepharmaceuticalintermedi-catalystsusedforhydrogenation,duetotheirun-ates,innon-acidicmedium,overdifferentsupportedsharedpairofelectrons.Thiseffectcanbeneutral-preciousmetal
6、catalysts(Scheme1),withhighcon-izedbyconversionofthesereactantstoaforminversionandselectivity.Inthesehydrogenations,thewhichthenitrogenatomisshielded,e.g.byaddinglightplatinummetals(Rh,Ru,Pd)provedtobetheproticacids[15].However,thismethodcannotmostactivecatalys
7、ts[69].Onthebasisofourhydro-beappliedifareactantissensitivetoacids,i.e.genationresults,itcouldbestatedthatthesaturationside-reaction,forinstance,polymerizationtakesplaceofpyrroleringtookplacerelativelyeasily,besidesininthepresenceofacids.Previously,wereportedth
8、ethesereductionsitwasunnecessarytouseacidstoheterogeneouscatalytichydrogenationsofsomepyr-avoidthedeactivationofthecatalysts.Althoughtherolederivatives(1-methyl-2-pyrroleeth
