【word】 钠灯下α蒎烯光敏氧化反应中区域选择性的催化调控（英文） .doc

钠灯下-蒎烯光敏氧化反应中区域选择性的催化调控（英文）2011饪七报ChineseJournalofCatalys/s,ol_32No.10文章编号:0253-9837(2011)10-1610-7国际版DOI:10.1016/Sl872.2067(10)60271.9研究论文:16101616钠灯下.蒎烯光敏氧化反应中区域选择性的催化调控游奎一,尹笃林,一,毛丽秋,刘平乐,罗和安,b湘潭大学化S-学院,湖南湘潭411105湖南师范大学化学化X-学院,湖南长沙410081摘要:发展了一种简单有效的d一蒎烯光敏催化氧化方法,该方法以高压钠灯为绿色光源,内循环氧气作为氧化剂和搅拌气,自制水浴式光化学反应器.考察了催化剂种类和反应条件对一蒎烯转化率和产物选择性的影响.结果表明,0【一蒎烯可通过催化一步生成单萜醇,醛和酮,且通过催化剂的酸碱协同作用可调节产物的区域选择性.当以N,N-.甲基甲酰胺为溶剂时,.蒎烯的转化率可达98%,主产物马鞭草烯酮和马鞭草烯醇的总选择性达到了84%.此外,还探讨了N,N-甲基甲酰胺酸碱协同催化的作用机理,并利用密度泛函计算结果对.蒎烯分子中化学反应活性和产物选择性之间的对应关系进行了合理的解释.关键词:光敏氧化;一蒎烯;催化调控;分子氧;N,N-甲基甲酰胺;密度泛函理论中图分类号:0643文献标识码:A收稿日期:2011-0613.接受日期:2011-08.20.通讯联系人.电话:(0731)88872576;传真:(0731)88872531;电子信箱:dulinyin126.tom通讯联系人.电话:(0731)58293545;传真:f0731)58298267;电子信箱:hluo基金来源:国家自然科学基金(21006081,20976043);湖南省自然科学基金(11JJ3024,09JJ8002);湖南省教育厅青年项目(11B122);湖南省科技计划项目(2010JT4051);新世纪优秀人才支持计划(NCET-100168).本文的英文电子版(国际版)由Elsevier出版社在ScienceDirect上出版(http:/www.sciencedirect.corn/science/journal/18722067).CatalyticModulationontheRegioselectivityofthePhotosensitizedOxidationofPinenewithMolecularOxygenunderSodiumLampIrradiationYOUKuiyi,YINDulin,MAOLiqiu,LIUPingle,LUOHean,CollegeofChemicalEngineering,XiangtanUniversity,Xiangtan411105,Hunan,ChinaCollegeofChemistryandChemicalEngineering,HunanNormalUniversity,Changsha410081,Hunan,ChinaAbstract:Asimpleandefficientphotosensitizedcatalyticoxidationapproachforapinenewithmolecularoxygeninatempera-turecontrolledreactorwithspargeddioxygenasoxidantandanimmersedhigh-pressuresodiumlampasagreenirradiationlightsourcewasdeveloped.Theeffectsofvariouscatalystsandreactionparametersonreactionperformancewerestudied.Theresultsindicatedthat98%conversionwim84%tota1selectivityforverbenoneandverbenolwasobtainedwhenN,N-dimethylformamide(DMF)wasusedasasolvent.TheproductdistributionswereremarkablyaffectedbythereactionmediaandDIFwasfoundtoespeciallymodulatetheregioselectivityoftheproducts.Moreover,apossiblephotosensitizedcatalyticoxidationreactionmechanisminDMFisproposedandaclearacidbasesyner-geticcatalysiseffectwasevident.TherelationshipbetweenchemicalreactivityandselectivitywasmodeledusingdensityftmctionaltheoryattheB3LYP/63l1+Gfd11evelfromoptimizedmolecularconfigurations.Keywords:photosensitizedoxidation;a-pinene;catalyticmodulation;molecularoxygen;NNdimethylformamide;densityfunctionaltheoryReceived13June2011.Accepted20August2011.“CorrespondingauthoF,Tel:+86-73188872576:Fax:+8673188872531,E-mail.UCorrespondinganthoF,Tel:+8673158293545,”Fax.”+86-73158298267:E-mail:hluoxtu.educnThisworkwassupportedbytheNationalNaturalScienceFoundationofChinaf2100608120976043)NaturalScienceFoundationofHu.nanProvincealJJ3024.O9J8002).ScientificResearchF姗d0fHunanProvincialEducationDepartmentfj1B122).ScientificandTechnologicalPlanP0jectofHunanProvinceI2010JT405l.andProgramlforNewCenturyExcellentTalentsinUniversity(NCET-IO一0168)EnglisheditionavailableonlineatElsevierScienceDirectttp:/游奎一等:钠灯下c【.蒎烯光敏氧化反应中区域选择性的催化调控16110【一Pineneisthemaincomponentofturpentineoilandisaninexpensive,readilyavailable,andrenewablestartingmaterialfortheproductionofawidevarietyofvaluableproductssuchasvariousflavors,fragrances,agrochemicals,andtherapeuticallyactivesubstances1,2.Theoxyfunc-tionalizationofc【.pineneisofspecia1interestsinceitsoxy.genatedproducts(verbenol,verbenone,myrtenal,myrtenol,andepoxideetc.1areusedinthesynthesisofintermediatesinfineandspecialtychemicalsincludingcitral,menthol,taxol,andvitaminsAandE3.Theselectiveoxidationofalkenesbymolecularoxygenisoneofthecurrentchallengesinthemanufactureofor-ganicbuildingblocksandindustrialintermediates4】.Thenoncatalyticoxidationofterpenesgenerallytakesplacewithpoorreproducibility,lowyields,andlowselectivities5_7.Therefore,thedevelopmentofcatalyticmethodsfortheselectiveoxidationof0【.pineneby”green”oxidantsisachallenginggoalinfinechemistry.Recently,photosensitizedcatalyticoxidationhasfoundmanyapplicationsinthesynthesisfieldanditholdsspecialpromiseforproductspecificity8-10.Unfortunately,controllingregioandstereoselectivityarestilldifficultissues11.Forexcellentselectivityinthesereactionsvariouseffortshavebeenmadeoverthepastfewdecadesandremarkablecontro1ofthereactionpathwayhasbeenachievedbytheuseoforganizedandconstrainedmedia12141.Inprevi-OUSwork,Murphyeta1.15reportedtheallylicoxyfimctionalizationofcyclicolefinsandabroadrangeofhomo.geneouscatalystsweretestedandsomeofthemaffordedayieldofmorethan90%ofthedesiredCc,B.unsaturatedketones.Guoetal-【16reportedthecatalyticselectivityofmetalloporphyrinsfortheaerobicoxidationofdoublebondsandtheallylicC-Hof0lpinene.TheresultsindicatedthatTPPMnClaffordedthelargestselectivityfortheoxidationofC=CbondsandTPPFeC1gavethelargestselectivityfortheoxidationofallylicC-Hbonds.Lieta1.17reportedcontrollableselectivityduringthephotooxidationofoleflnssensitizedbv9,l0-dicyanoanthraceneunderultravioletlightirradiation(witha450WmediumpressureHglampasalightsource).Thesewereincludedinvesiclesgivingeneproductsandnoneneproducts.Theseresultsindicatethattheorganizedsemirigidenvironmentinvesiclespreventstheolefinmoleculesfromconformationalchange.Allaleta1.18systematicallyinvestigatedthenatureofthecatalyst.theoxidizingagentandthereactionconditionsfortheallylicoxidationof0【.pinenecatalyzedbyatransitionmetalusingt-butylhydroperoxide(TBHP)andhydrogenperoxide.TheresultsshowedhighselectivityforverbenonewasachievedundermildconditionswhenusingcoppersaltsascatalystsandTBHPasanoxidant.Yangeta1.19reportedthecatalyticselectivityofTiO,fortheepoxidationofdou.blebondsofa-pinene,andthegoodselectivityofepoxidationproductwasobtained.Theprimaryresultsofourinvestigationintothephotosensitizedoxidationofthreemonoteroeneswithmolecularoxygensensitizedbytetrachlorotetraiodo.fluoresceinso.diumsaltf1B1undervisiblelightirradiationhavebeenreportedpreviously201.Herein,wereportdetailedresultsfromaninvestigationintotheOhOtOsensitizedoxidationof0l-pinenewithmoleculeoxygeninthepresenceofvariouscatalyticsystems.Moreover,therelationshipbetweenchemicalreactivityandselectivitywasmodeledbydensityfimctionaltheory(DFT)calculations.1Experimenta1.1PhotosensitizedoxidationexperimentA11theDhOtOsensitizedoxidationreactionswereper.formedaccordingpreviouswork20.0【一Pinenewasdis.tilledunderreducedpressurefromturpentineoil.A11theotherchemicalswereofanalyticalgradeandusedaspurchased.A110Whigh.pressuresodiumlampwasusedasthegreenirradiationsource.ThefinalproductswereidentifledbyGC.MSandquantitativelyanalyzedbytheintemalstandardmethod.Gaschromatography(GC)wasperformedonanAgilent6890equippedwithanFIDdetector.Massspectra(MS)wereobtainedfromanAmericaVarianSaturn210OTGCMSinstrument.1.2TheoreticalbackgroundandcomputationaldetailsDFTlocaldescriptorsareusefulindescribingchemicalreactivity.AwellknownexampleistheFukuifunction2124.Forasystemwithelectrongain厂(isusedastheindexfornucleophilicattack.Forelectrondonation厂fr1isusedastheindexforelectrophilicattack.Theaverageofthetwo,f”(=(厂(+f(r)/2,representstheradicalaRackability.ThecondensedFukuifunctionsarebasedonapopulationanasNBOchargesonatomkinamoleculewith+1,and_1electrons,respectively.InthisworktheFukuifunctionvalueofatypicalcarbonatominthemolecularstructureof0【一pinenewascalculatedbytheabove-mentionedmethod.Allthegeometricaloptimizationsforc【-pineneandhydroperoxideintermediateswerecarriedoutusingaDFThybridexchange-correlationenergydensityfunctionalcon?1612催化Chin.Cata1.,2011,32:1610-1616sistingoftheBeckesthreeparameterizedexchangeenergydensityfunctionalandtheLee.Yang.Parrcorrelationfunc.tiona1I2529.A11calculationswerecarriedoutattheDFTB3LYP/631l+G(d)levelwiththeGAUSSIAN-03package,versionE02,withtightSCFconvergenceandultrafineinte.grationgrids.2Resultsanddiscussion2.1Photosensitizedcatalyticoxidationofn-pineneindiflferentmediaTheRBsensitizedDhOt0Oxidati0nreactionofC【.pinenewithmolecularoxygenwasexaminedindifierentreactionmedia.Afterirradiationbyahighpressuresodiumlamptheeneproductsverbenol(2),myrtenol(5),andthe/tOneneproductsmyrtenal(4),verbenone(3),4-hydroxy一2,3-epioxypinane(6),and1-hydroxy-2,3-epioxypinane(7)wereobtained(seeScheme1,.Theproductsselectivitydis.tributionsinvariouscatalyticsystemsaregiveninrable1.FromT_ab1e1itisobviousthatthevariouscatalystscatalyzetheDhOtOsensitizedoxidationreactionofcc.pinenetosomeextent.Theoxidationreactionhardlyoccurredintheabsenceof1ightirradiation.ThisindicatesthatthehighpressuresodiumlampplaysanextraordinarilyimportantroleintheDh0tosensitizedoxidationreaction.Singletoxy.02,hv,SensitizerSolvent,Catalyst23+genisgeneratedbyanenergytransferprocessduringacol-lisionoftheexcitedsensitizerwithtripletmolecularoxy.gen.Howevesensitizerexcitationisgenerallyachievedbyaonephotontransition(betweenthegroundstateandasingletexcitedstate30.Therefore,thelightsourceisessentialtoDhOtOsensitizedoxidation.Amongthesecatalysts2,6-dimethylpyridinecombinedwithaceticanhydridegivesthebestresultswith97%conversion.42%selectivityforverbenone(3),and36%selectivityforverbenol(2)inamethylalcoholsolution.Aspecia1OhOtOsensitizedoxidationreactioneffectwasobservedwhenDMFwasusedasasolventastheconversionofmaterialandselectivityforthemainproductimprovedsignificantly.Thebestresultsof98%conversionwith51%selectivityforverbenoneand33%selectivityforverbenolwasobtainedintheabsenceofanycatalystswhileonlylowamountsofresiduewasob.tained.ApossiblereasonisthatDMFcanconverttoazwit.terionresonancestructurewithaNpositiveionandanOnegativeion.Therefore.DMFpossessesthecharacteristicsofacidsandbases,whichpromotesthedecompositionofthehydroperoxideintermediatestothecorrespondingaide-hydesandketonesorareductiontoalcohols.Therefore,theconversionofmaterialandselectivityfortheproductishigherunderacidbasesynergeticcatalysis.TheformationmechanismoftheDhOt0sensitizedoxidationproductsinDMFhasbeenreportedinourpreviouswork20.45Scheme1.Photosensitizedcatalyticoxidationofupinenewithmolecularoxygen60HTable1ProductdistributionsfortheRBsensitizedphotocatalyticoxidationindifferentmedia+7Reactionconditions:reactiontemperature300K,reactiontime4h.Determinedbytheintemalstandardmethod.ReferstononvolatilesubstancesthathavenoGCpeaks.Noirradiationlightsource.Composites(themixtureof2,6.dimethylpyridineandaceticanhydride)wereaddedintothesystemafterthereaction.游奎一等:钠灯下0【一蒎烯光敏氧化反应中区域选择性的催化调控l613Theselectivityandconversionareaffectedbythecatalystadditionmethod.Theselectivityandconversionwasfoundt0befarhigherwhenthecompositecatalystswereaddeddirectlytothesystembeforethereactioncomparedtoafterthereaction.Theobtainedresultsshowthattheselectivityandconversionstronglydependonthereactionmedia.Inthiswork,thecompositeof2,6一dimethylpyridineandaceticanhydridepossessesacidandbasecharacteristicsandcan,therefore,promotethedecompositionofthehydroperoxideintermediatetothecorrespondingproducts.Therefore,2,6一dimethylpyridinecombinedwithaceticanhydride,asacomposite,wasselectedasatypicalcatalysttoinvestigatethereactionconditionsofthephotosensitizedoxidation2.2Effectsof2,6-dimethylpyridinewithdifferentamountsofaceticanhydrideonthephotosensitizedoxidationof-pineneTheexperimentalresultsfromthephotosensitizedoxidationofa-pineneuponcatalysisby2,6一dimethylpyridinecombinedwithdifferentamountsofaceticanhydridearesummarizedin1able2.Theconversionof0lpineneincreasedinitiallyandthendecreasedgraduallybecauseofthehigheramountofaceticanhydride.However,theselectivityforverbenonedecreasedgraduallyandtheamountofresiduedecreasedinitiallyandthenincreased.Theconversionof0【.pinenewas97%with42%selectivityforverbenoneand36%selectivityforverbeno1ata1:1molarratioof2,6一dimethylpyridinetoaceticanhydride.However,theconversionandselectivityhadadecliningtrendandtheamountsofresidueincreasedgraduallywhenthemolarratioexceeded1:1.Apossiblereasonisthattheexcessaceticanhydrideaggravatedthepolymerizationofallylicperoxidefreeradicalsand,thus,theselectivityforresiduesincreasedandtheselectivityforthemainproductdecreased.Therefore,asuitableamountofaceticanhydridecanefficientlycatalyzetheDhOtOsensitizedoxidationofccpinene.Theseresultsconfirmthattheacid-basesynergisticcatalyticprop-ertiesof2,6.dimethylpyridineandaceticanhydridehaveanTable2ProductdistributionsfortheRBsensitizedphotooxidationcatalyzedby2,6一dimethylpyridinecombinedwithaceticanhydrideReactionconditions:methanolassolvent,reactiontemperature300K,reactiontime4h.Themolarratioof2,6一dimethylpyridinetoaceticanhydride.importantinfluenceontheconversionandselectivityinthephotosensitizedoxidationofapinene.2.3Effectsofreactiontimeontheph0tosensitizedoxidationofa-pineneTheeffectofreactiontimeontheconversionofccpineneandselectivicyforverbenoneinedat300K.Theresultsarehtheconversionof0【一pineneandtheresidueswasexamshowninFig.1.Inthefirst4andtheselectivityforverbenoneincreaseddramaticallyto97%and42%.respectively,whiletheselectivityfortheresiduesdecreasedgraduallyto1%.Thereactionratethengraduallyslowedandtheconversionof0【一pinenegraduallyincreasedto98%at5h.Moreover,theselectivityforverbenonedecreasedslightlywhiletheselectivityfortheresiduesincreasedrapidlyfrom1%tol2%whenthereactiontimeexceeded4h.Apossiblereasonisthatthepolymerizationoftheallylicperoxidefreeradicalwasaggravatedwithanincreaseinthereactiontimeand,thus,selectivityfortheresiduesincreasedandselectivityforthemainproductdecreased.Therefore.selectingtheappropriatereactiontimeisessentialinthephotosensitizedoxidationofccpinene.100200l2345Reactiontimerh1Fig.1.Effectsofreactiontimeoilthephotosensitizedoxidationuponcatalysisby2,6一dimethylpyridineandaceticanhydride.Reactioncon-ditions:molarratioof2,6一dimethylpyridinetoaceticanhydride1:1,reactiontemperature300K.2.4Effectsofreactiontemperatureontheph0tOsensitizedoxidationofu-pineneTheeffectofreactiontemperatureontheDhotosensitizedoxidationof0【一pinenecatalyzedby2,6一dimethylpyridinecombinedwithaceticanhydridewasexamined.Theresultsarelistedin1able3.Thereactiontemperaturesignificantlyinfluencestheconversionofupineneandtheselectivityfortheresidues.Theconversionincreasedrapidlywithanin.creaseinthereactiontemperaturefrom34%at273Kto98%at310K.Theselectivityforverbenoneandverbeno1一o/0一占IA口u0g1l0矗【10u1614催化Chin.Cata1.,2011,32:1610-1616Table3Influenceofreactiontemperatureonthephotosensitizedoxidationofct-pineneuponcatalysisby2,6一dimethylpyridineandaceticanhydrideReactionconditions:methanolassolvent,themolarratioof2,6一di-methylpyridinetoaceticanhydride1:1,reactiontime4h.increasedgraduallywithtemperaturebetween273and300K.However,theselectivit