ꢀ
YanliꢀCuiꢀetꢀal.ꢀ/ꢀChineseꢀJournalꢀofꢀCatalysisꢀ36ꢀ(2015)ꢀ322–327ꢀ
323ꢀ
arylboronicꢀ acidꢀ inꢀ theꢀ presenceꢀ ofꢀ PdCl
2
ꢀ andꢀ Pd(dba)
2
ꢀ
resultingꢀsuspensionꢀwasꢀheatedꢀtoꢀ140ꢀ°Cꢀforꢀ30ꢀmin.ꢀWaterꢀ
(2.5ꢀ mL)ꢀ wasꢀ thenꢀ addedꢀ toꢀ theꢀ reaction,ꢀ andꢀ theꢀ resultingꢀ
mixtureꢀwasꢀreducedꢀforꢀ2ꢀhꢀatꢀ180ꢀ°Cꢀtoꢀgiveꢀtheꢀ3ꢀwt%ꢀPd/SiCꢀ
catalyst.ꢀ
Theꢀ Pdꢀ contentꢀ ofꢀ theꢀ catalystꢀ wasꢀ determinedꢀ byꢀ induc‐
tivelyꢀcoupledꢀplasmaꢀ(ICP)ꢀatomicꢀemissionꢀspectrometryꢀus‐
ingꢀanꢀAtomscanꢀ16ꢀsystemꢀ(ThermoꢀFisherꢀScientific,ꢀShang‐
hai,ꢀChina).ꢀTheꢀphaseꢀcharacterizationꢀofꢀtheꢀcatalystꢀwasꢀde‐
terminedꢀ usingꢀ aꢀ Rigakuꢀ D‐Max/RBꢀ X‐rayꢀ diffractionꢀ (XRD)ꢀ
(bis(dibenzylideneacetone)palladium).ꢀThisꢀreactionꢀprovidesꢀaꢀ
versatileꢀplatformꢀforꢀtheꢀdirectꢀsynthesisꢀofꢀaromaticꢀketonesꢀ
usingꢀboronicꢀacids,ꢀwhichꢀareꢀgenerallyꢀnon‐toxicꢀandꢀstableꢀtoꢀ
ꢀ
airꢀandꢀmoisture.ꢀIshiyamaꢀetꢀal.[10]ꢀusedꢀaꢀvarietyꢀofꢀdifferentꢀ
catalystsꢀtoꢀaffectꢀthisꢀcarbonylativeꢀSuzukiꢀreaction,ꢀincludingꢀ
2 3 2 2
PdCl ꢀ (PPh ) ꢀ andꢀ PdCl ꢀ (dppf)([1,1'‐bis(diphenylphosphino)
ꢀ
ferrocene]dichloropalladium(II)).ꢀHowever,ꢀtheꢀconversionꢀandꢀ
selectivityꢀofꢀtheseꢀreactionsꢀareꢀlowꢀandꢀrequireꢀtheꢀpresenceꢀ
ofꢀaꢀligandꢀtoꢀproceedꢀeffectively.ꢀKhedkarꢀetꢀal.ꢀ[11]ꢀreportedꢀ
thatꢀimmobilizedꢀpalladiumꢀion‐containingꢀionicꢀliquidsꢀexhib‐
itedꢀexcellentꢀcatalyticꢀactivityꢀtowardsꢀtheꢀcarbonylativeꢀSuzu‐
kiꢀcouplingꢀreactionꢀofꢀarylꢀhalidesꢀwithꢀarylboronicꢀacids,ꢀwithꢀ
theꢀ coupledꢀ productsꢀ beingꢀ isolatedꢀ inꢀ highꢀ yields.ꢀ However,ꢀ
theꢀoverallꢀutilityꢀofꢀthisꢀprocessꢀisꢀlimitedꢀbyꢀitsꢀrequirementꢀ
forꢀtheꢀuseꢀtoxicꢀorganicꢀcompounds,ꢀwhichꢀareꢀharmfulꢀtoꢀtheꢀ
environment.ꢀNiuꢀetꢀal.ꢀ[12]ꢀreportedꢀtheꢀstabilizationꢀofꢀPdꢀonꢀ
hollowꢀmagneticꢀmesoporousꢀspheresꢀandꢀtheꢀuseꢀofꢀthisꢀmate‐
rialꢀ asꢀ aꢀheterogeneousꢀcatalysisꢀ forꢀtheꢀcarbonylativeꢀSuzukiꢀ
couplingꢀreaction.ꢀHowever,ꢀtheꢀpreparationꢀofꢀthisꢀcatalystꢀisꢀ
complex.ꢀTherefore,ꢀdespiteꢀgoodꢀprogressꢀduringꢀtheꢀlastꢀ20ꢀ
yearsꢀ towardsꢀ theꢀ developmentꢀ ofꢀ robustꢀ methodsꢀ forꢀ theꢀ
preparationꢀofꢀaromaticꢀketones,ꢀtheꢀhighꢀcostsꢀassociatedꢀwithꢀ
theꢀpreparationꢀofꢀcomplexꢀcatalystsꢀandꢀligands,ꢀandꢀtheꢀdiffi‐
cultiesꢀinvolvedꢀinꢀtheꢀseparationꢀofꢀcatalystsꢀfromꢀtheꢀreactionꢀ
mixtureꢀhaveꢀgreatlyꢀlimitedꢀtheꢀapplicationꢀandꢀdevelopmentꢀ
ofꢀtheꢀcarbonylativeꢀSuzukiꢀcouplingꢀreaction.ꢀBasedꢀonꢀtheseꢀ
limitations,ꢀ thereꢀ isꢀ stillꢀ considerableꢀ scopeꢀ forꢀ exploringꢀ theꢀ
developmentꢀ ofꢀ newꢀ stableꢀ andꢀ efficientꢀ heterogeneousꢀ cata‐
lystsꢀforꢀtheꢀcarbonylativeꢀSuzukiꢀcouplingꢀreaction.ꢀ
systemꢀ(Tokyo,ꢀJapan)ꢀusingꢀCu‐K
ꢀradiation.ꢀTheꢀstructureꢀandꢀ
α
morphologyꢀofꢀtheꢀcatalystꢀwereꢀcharacterizedꢀbyꢀtransmissionꢀ
electronꢀ microscopyꢀ (TEM)ꢀ usingꢀ aꢀ JEM‐2100Fꢀ systemꢀ (JEOL,ꢀ
Tokyo,ꢀ Japan).ꢀ X‐rayꢀ photoelectronꢀ spectroscopyꢀ (XPS)ꢀ meas‐
urementsꢀwereꢀconductedꢀonꢀanꢀESCALABꢀ3ꢀMKIIꢀdeꢀVGꢀspec‐
trometerꢀ(VGꢀScientific,ꢀEastꢀSussex,ꢀUnitedꢀKingdom)ꢀusingꢀMgꢀ
α
K ꢀ(15ꢀkV,ꢀ20ꢀmA)ꢀasꢀanꢀX‐rayꢀsource.ꢀ
2.2.ꢀ ꢀ CarbonylativeꢀSuzukiꢀcouplingꢀreactionsꢀ
Allꢀ ofꢀ theꢀ carbonylativeꢀ Suzukiꢀ couplingꢀ reactionsꢀ wereꢀ
conductedꢀ inꢀ aꢀ sealedꢀ stainlessꢀ steelꢀ reactionꢀ kettle.ꢀ Aryl‐
boronicꢀ acidꢀ (1.5ꢀ mmol),ꢀ arylꢀ iodideꢀ (1.0ꢀ mmol),ꢀ baseꢀ (3.0ꢀ
mmol),ꢀ3ꢀwt%ꢀPd/SiCꢀandꢀanisoleꢀ(10ꢀmL)ꢀwereꢀaddedꢀtoꢀtheꢀ
reactionꢀkettle,ꢀandꢀtheꢀresultingꢀmixtureꢀwasꢀplacedꢀunderꢀaꢀ
certainꢀpressureꢀofꢀCO.ꢀAllꢀofꢀtheꢀreactionsꢀwereꢀconductedꢀoverꢀ
severalꢀhoursꢀatꢀcertainꢀtemperatures.ꢀTheꢀproductsꢀofꢀtheꢀre‐
actionsꢀ wereꢀ analyzedꢀ byꢀ GC‐MSꢀ onꢀ aꢀ Brukerꢀ SCIONꢀ SQꢀ 456ꢀ
GC‐MSꢀsystemꢀ(Karlsruhe,ꢀGermany).ꢀ
3.ꢀ ꢀ Resultsꢀandꢀdiscussionꢀ
SiCꢀhasꢀexcellentꢀchemicalꢀstabilityꢀandꢀthermalꢀconductivityꢀ
properties,ꢀandꢀhasꢀbeenꢀsuccessfullyꢀusedꢀasꢀcatalystꢀsupportꢀ
inꢀvariousꢀcatalyticꢀreactions,ꢀincludingꢀtheꢀoxidationꢀofꢀCO[13],ꢀ
3.1.ꢀ ꢀ MorphologyꢀandꢀstructureꢀofꢀtheꢀPd/SiCꢀcatalystꢀ
ꢀ
reformingꢀofꢀCH
4
ꢀandꢀCO2ꢀ[14,15],ꢀphotocatalyticꢀwaterꢀsplittingꢀ
TheꢀPdꢀloadingꢀofꢀtheꢀPd/SiCꢀcatalystꢀwasꢀdeterminedꢀtoꢀbeꢀ
2.91ꢀwt%ꢀbyꢀICP‐MSꢀanalysis,ꢀwhichꢀisꢀsimilarꢀtoꢀtheꢀcalculatedꢀ
value.ꢀBETꢀanalysisꢀshowedꢀthatꢀtheꢀsurfaceꢀareaꢀofꢀtheꢀPd/SiCꢀ
ꢀ
ꢀ
[
[
16],ꢀmethanation[17]ꢀandꢀtheꢀphotocatalyticꢀreductionꢀofꢀCO
18].ꢀWeꢀrecentlyꢀreportedꢀthatꢀSiC‐supportedꢀPdꢀnanoparticlesꢀ
2
2
significantlyꢀenhancedꢀtheꢀhydrogenationꢀofꢀfuranꢀderivativesꢀ
underꢀlowꢀtemperatureꢀ(25ꢀ°C)ꢀandꢀlowꢀpressureꢀ(1.0ꢀMPaꢀofꢀ
catalystꢀwasꢀ56ꢀm /g.ꢀTheꢀTEMꢀimagesꢀofꢀtheꢀPd/SiCꢀcatalystꢀ
(Fig.ꢀ 1)ꢀ showedꢀ thatꢀ homogeneousꢀ metallicꢀ Pdꢀ nanoparticlesꢀ
wereꢀuniformlyꢀdispersedꢀonꢀtheꢀSiCꢀsurfaceꢀwithꢀaꢀnarrowꢀsizeꢀ
distributionꢀ ofꢀ 1–5ꢀ nmꢀ andꢀ aꢀ meanꢀ diameterꢀ ofꢀ 2.8ꢀ nm.ꢀ Theꢀ
latticeꢀfringeꢀofꢀtheꢀnanoparticlesꢀhadꢀanꢀinterplanarꢀspacingꢀofꢀ
0.19ꢀnm,ꢀwhichꢀwasꢀinꢀagreementꢀwithꢀtheꢀ(200)ꢀplaneꢀofꢀPd.ꢀ
TheꢀXRDꢀpatternꢀofꢀtheꢀPd/SiCꢀcatalystꢀ(Fig.ꢀ2)ꢀshowedꢀthatꢀallꢀ
ofꢀtheꢀstrongꢀdiffractionꢀpeaksꢀcouldꢀbeꢀindexedꢀtoꢀβ‐SiC.ꢀTheꢀ
2
H )ꢀ conditionsꢀ byꢀ visibleꢀ lightꢀ irradiationꢀ [19].ꢀ Notably,ꢀ theꢀ
yieldꢀofꢀtetrahydrofuranꢀfromꢀtheꢀhydrogenationꢀofꢀfuranꢀunderꢀ
–1
theseꢀconditionsꢀwasꢀ99%ꢀwithꢀaꢀturnoverꢀfrequencyꢀofꢀ70ꢀh .ꢀ
Inꢀthisꢀstudy,ꢀaꢀPd/SiCꢀcatalystꢀhasꢀbeenꢀpreparedꢀbyꢀaꢀliquidꢀ
reductionꢀmethodꢀusingꢀhighꢀsurfaceꢀareaꢀSiCꢀasꢀaꢀsupport,ꢀandꢀ
investigatedꢀitsꢀcatalyticꢀperformanceꢀtowardsꢀtheꢀcarbonyla‐
tiveꢀSuzukiꢀcouplingꢀreactionꢀunderꢀheterogeneousꢀconditions.ꢀ
(
a)
(b)
0
.19 nm
2.ꢀ ꢀ Experimentalꢀ
Pd(200)
2.1.ꢀ ꢀ PreparationꢀandꢀcharacterizationꢀofꢀPd/SiCꢀ
2 nm
Theꢀ Pd/SiCꢀ catalystꢀ (3ꢀ wt%)ꢀ wasꢀ preparedꢀ usingꢀ aꢀ liquidꢀ
phaseꢀ reductionꢀ method.ꢀ Palladiumꢀ nitrateꢀ (132.6ꢀ mg,ꢀ 0.564ꢀ
2
mmol)ꢀandꢀSiCꢀpowderꢀ(1.94ꢀg,ꢀSBETꢀ=ꢀ50ꢀm /g)ꢀwereꢀdispersedꢀ
50 nm
10 nm
inꢀabsoluteꢀethanolꢀ(50ꢀmL)ꢀunderꢀsonicationꢀconditions,ꢀandꢀ
theꢀresultingꢀsuspensionꢀwasꢀmagneticallyꢀstirredꢀtoꢀgetꢀaꢀho‐
mogenousꢀ mixtureꢀ ofꢀ palladiumꢀ nitrateꢀ andꢀ SiC.ꢀ Theꢀ mixtureꢀ
wasꢀ dispersedꢀ inꢀ 80ꢀ mLꢀ ofꢀ diethyleneꢀ glycolꢀ (DEG),ꢀ andꢀ theꢀ
1
2
3
4
5
Nanoparticle size (nm)
Fig.ꢀ1.ꢀTEMꢀandꢀHRTEMꢀimagesꢀ(insetꢀofꢀ(b))ꢀofꢀPd/SiCꢀcatalyst,ꢀandꢀtheꢀ
sizeꢀdistributionꢀofꢀPdꢀnanoparticlesꢀ(insetꢀofꢀ(a)).ꢀ
Cui, Yanli
