Synthesis and derivation of chlorofunctionalized organosilicon polymers via acyclic diene metathesis polymerization PDF
Preview Synthesis and derivation of chlorofunctionalized organosilicon polymers via acyclic diene metathesis polymerization
SYNTHESISANDDERIVATIZATIONOFCHLOROFUNCnONALIZED ORGANOSIUCONPOLYMERSVIAACYCUCDIENE METATHESISPOLYMERIZATION By SOPfflAKAYCUMMINGS ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOLOF THEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT OFTHEREQUIREMENTSFORTHEDEGREEOF DOCTOROFPHILOSOPHY UNIVERSITYOFFLORIDA 1997 Thisdissertationisdedicatedtomyparents, SylvesterandMildredStevenson, fortheirparentalwisdominbuildingcor^dence andintegrity,andacceptingnothing buttheverybestfromme, andtomyhusband, JerryL.Cummings,Sr., forbeingmyconstantsourceofsupportand encouragementthroughoutmygraduatecareer. ACKNOWLEDGEMENTS SincerethanksareextendedtothepastandpresentmembersoftheWagenergroup: Dr. Jason Portmess, Dr. John Anderson, Dr. John O'Gara, Dr. Chris Marmo, Dr. KathleenNovak,Dr.DehuiTao,Dr.ReginaSchitter,Dr.FabioZuluaga,Dr.Krystina Brzezinska,CameronChurch,TammyDavidson,FernandoGomez,LauriJenkins,Mary Schmidt,JasonAbrams,DebraTindall,DominickValenti,MarkWatson,andShane Wolfe. AlsospecialthanksgotothepastandpresentmembersoftheDuranandReynolds groupforcreatingaresearchenvironmentinwhichtheexchangeofscientificknowledge wasenjoyable. SpecialthanksgotoJenniferBatten,JenniferIrvin,BernardLiburd,Michelle Fletcher,SheritaMcLamore-Long,andDr.ValerieFayefortheirspecialfriendshipduring mygraduatecareer. SpecialrecognitionisgiventoLorraineWilliamsforherwarmpersonality, willingnesstohelpstudents,andexcellentorganizationskills. Recognitionisalsogivento CarolLoweforherwillingnesstoalwayslendalisteningear. Specialrecognitionisgiven toDr. Gary Burns forhiscollaboration and helpful insightinto silconchemistry. RecognitionisfinallygiventotheArmyResearchOfficeforfundingthisproject. Finally,theutmostrepectisgratefullyextendedtoProfessorKenWagenerforhis patienceandpositiveattitude,whichareaninspirationforme,andforbeingamentorwho isalwayssupportiveofhisstudents. iii TABLEOFCONTENTS Page ACKNOWLEDGEMENTS iu ABSTRACT W CHAPTERS 1 nmODUCTION. 1 HistoryofOrganosiliconChemistry. 1 PropertiesandCharacteristicsofSilicoa 5 HistoryofSilicon-BasedPolymer. 8 OlefinMetathesis. 17 CatalystSystemsfortheOlefinMetathesisReaction 22 DevelopmentoftheOlefinMetathesisMechanism. 23 DevelopmentofLewisAcidFreeAlkylideneCatalysts. 26 RingClosingMetathesis. 29 RingOpeningMetathesisPolymerization. 30 AcyclicDieneMetathesisPolymerization. 31 2 EXPERIMENTAL InstrumentationandAnalysis. 39 Materials. 40 V i Techniques. 40 SynthesisandCharacterization 41 ModelStudies. 41 MonomerSynthesis. 45 ADMETPolymerizations. 48 MacromolecularSubstitutionReactions. 52 3 DESIGNANDSYNTHESISOFCHLOROFUNCTION ALEEDPOLYCARBOSILANES 54 SyntheticRulesGoverningADMETReactions. 59 ChlorocarbosilaneMonomerSynthesis. 63 AdmetPolymerizationofCarbosilaneDienesPossessing theSi-ClBond. 69 ADMETCopolymerizationsofCarbosilaneDienes PossessingtheSi-ClBond. 74 ThermalAnalysisofChlorofunctionalizedADMETPolymers. 76 Conclusions. 79 4 POLYCARBOSILANEDERIVATIVESFROMPOLYCARBO SILANEINTERMEDIATESCONTAININGTHESi-QBOND. 80 ModelSubstitutionReactions. 85 DesignandSynthesisofPolycarbosilaneDerivatives FromMacromolecularSubstitutionReactions. 89 ThermalAnalysisofCarbosilanePolymerDerivatives. 90 Conclusions. 94 REFERENCES 95 BIOGRAPHICALSKETCH. 106 V AbstractofDissertationPresentedtotheGraduateSchool oftheUniversityofFloridainPartialFulfillmentofthe RequirementsfortheDegreeofDoctorofPhilosophy SYNTHESISANDDERIVATIZATIONOFCHLOROFUNCTIONALIZED ORGANOSILICONPOLYMERSVIA ACYCLICDIENEMETATHESIS POLYMERIZATION By SophiaKayCummings August1997 Chairman: ProfessorKennethB.Wagener MajorDepartment: Chemistry Thedesign,synthesis,andderivatizationofunsaturatedorganosiliconpolymers possessingtheSi-Clbondispresentedherein. Silicon-basedunsaturatedpolymersmaybe synthesizedbyacychcdienemetathes(ADMET)polymerization,whichhasbeenshownto beacleanroutetounsaturatedpolymers. TheSi-Clbondinunsaturatedcarbosilane monomersremainsinertduringmetathesisandtheuseofahighlyactivemolybdenum- based,Lewis acid-freealkylidene catalystaffords unsaturatedchlorofunctionalized carbosilaneoligomersandpolymers. Various polymers and copolymers possessing the Si-Cl functionality were synthesizedinordertostudythephysicalpropertiesofthesesystems. Theunsaturated carbosilanematerialsproducedpossessvinylgroupsastheirendgroupsandhavea predominantlytransgeometryaboutthebackbonedoublebond. Thechlorofunctionalized Vi carbosilanepolymerssynthesizedwereelastomericmaterials,thatshowgoodthermal stabilityinbothairandnitrogenatmospheres. ThesuccessofADMETchemistryhasprovidedaccesstoapolymersystemthathas thepotentialtobeausefulmacromolecularintermediate,whichmaybederivatizedwitha varietyoffunctionalgroups. Macromolecularsubstitutionreactionswereperformedon chlorofunctionalizedmonomersandpolymers. Substitutionsproceededasexpectedwith smallmoleculereactions,withalargeexcessofnucleophilebeingrequiredforcomplete substitution. Macromolecularsubstitutionreactionsgeneratedmaterialswhichwere insoluble,solventresistant,andshowedgoodthermalstability. VII CHAPTER 1 INTRODUCTION HistoryofOrganosiliconChemistry Organosiliconcompoundshavebeenknownsincethemid-1800sandtodayare foundinapplicationsrangingfromsolutionstosyntheticmaterialstohealthcareproductsto computer chips. While organosilicon research began with the synthesis of Si-C compounds, laterresearchinterestshaveexpandedtoSi-NandSi-0, aswellasSi compoundswithothergroupVIelements. Besidesthesyntheticaspects,organosilicon chemistryhasbecomeamajortool forthepreparationofreactiveintermediiatesinorganic synthesis.^ Investigatorsbeganaquest,whichcontinuestoday,forknowledgeofjustwhat siliconcanacheiveintermsofitsbonding. Indeed,allofthesethingsmakeorganosilanes interestingsubjects. Silicondoesnotexistfreeinnature. However,naturedoesprovideuswiththe primarysourceofsilicon,silicondioxide(SiOi). Whensilicaiscombinedwithmetal oxides,silicondioxideorsilicatesareformedandexhibitavariationinstructuralchemistry. Siliconissecondinterrestrialabundance,andtheearth'scrustis75%siliconandoxygen. Thiscompareswithcarbon,whichislessthan1%. Thenamesiliconwasderivedfromthe Latinwordsilex,meaningrock,andwasdesignedtodrawattentiontoitsrelationshiptothe elementscarbonandboron.^ Astherearenonaturallyoccurringorganosilanes,allorganosilaneshavetheir beginningwithsilicondioxide. Organosiliconcompoundswerefirstreportedin1863 1 2 whenFriedelandCraftspreparedtetraethylsilanefromtetrachlorosilaneanddiethylzinc.^ At the turn ofthecentury Frederic Kipping, who isreferred to as the "fatherof organosiliconchemistry,"beganthefirstsystematicstudyofsiliconcompounds. His intentionwastosynthesizeanopticallyactivecompoundbasedonanalogytocarbon chemistryandin1899Kippingbegantopublishaseriesofpaperswhichlaidthefoundation ofmodemsiliconchemistry. Hebegantorealizethatsiliconandcarbondidnotproduce identicalseriesofcompoundsandtheearlyinvestigatorsofsiliconchemistryseemedto viewtheelementasa"failure"fornotfollowingthemodelsetbycarbon. Theuniqueness thatorganosiliconcompoundspossesswasnotappreciatednordeemeddesirableuntilafter Kippingretired. AtthattimeEugeneRochowdevelopedanewmethodforforming organosiliconcompounds,whichwastoformthebasisofanewundustryandprovidethe impetusbehindanexpandedinterestinthechemistryofsilicon.^-^ SinceSi-Cbondsdonotoccurinnature,thekeytoorganosiUconchemistrymustbe intheformationofthisbond. Thefirstorganosiliconderivative,tetraethylsilane,was generatedbyFriedelandCrafts^byheatingdiethylzincandtetrachlorosilaneinasealedtube at140-160°C. In1900KippingreactedSiCUwithEtMgltoobtainamixtureofR-Si-X compounds. ThisGrignardroutestillprovedtobeamajorimprovementoverzinc derivatives. LaterKippingdescribedaseriesofsuccessiveGrignardadditionstoobtain PhEtPrSiMe(Figure1.1).^ ™g^^> P'^^g^^^ SiCI, EtSiCl3 EtPhSiCl2 PrMgBr^ EtPhPrSiCl MeMgB^ EtPhPrSiMe Figure1.1. Kipping'sGrignardroutetoorganosiliconderivatives. 3 Ingeneral,theeaseofreplacementofSi-halogen(orSi-alkoxide)bonddecreaseswith increasingnumberoforganicgroupsonsilicon. Theapproachtotheconstructionofan organosiliconderivativewilldependonhowmanyorganicgroupsandhowmanyfunctional groupswillberequiredatsiliconinthetargetmolecule. Whenorganometallicreagentsare reactedwithpolychlorosilanes,productmixturesareusuallyobtained. Acommontacticto avoidmultiplesubstitutionistoincreasetheratioofsilylchloridetoorganometallicreagent. Thesolventorsolventmixturemayalsoaffecttheproductdistribution. Basicsolventssuch asTHFcanconverttheorganometallicreagentintoamoreactivenucleophiletofavorthe completelysubstitutedproduct. Amorenucleophilicsolventisalsorequiredforsuccessful additionofbulkysubstituents. Therearebasicallythreetypesofsiliconfunctionalgroups that react with organometallic reagents: Si-X (X=halogen), Si-OR, and Si-H. OrganolithiumreagentscouplewithallthreegroupsandGrignardreagentswithSi-Xand Si-ORgroups. AlthoughthekeytotheformationofSi-Ccompoundswasdiscoveredintheearly 1900s,thereactionproducedundesirablesideproductswhichmadethisroutelessthan desirableforlarge-scaleproduction. Thesolutiontothisproblemwasprovidedbythe discoveryofthedirectprocessreactioninthe1940sbyE.G.Rochow.^ Coppercatalyzed siliconwasreactedwithSiCUatelevatedtemperaturesinasealedtubetoproduceambcture oforganosilanes(Figure 1.2). Thetrickseemedtobefindinganappropriatecatalyst (copper)thatwouldallowthereactiontorunatalowertemperatureandminimizeside reactionsduetopyrolysis. ThediscoveryoftheRochowprocessprovidedafirmfooting forthefutureoforganosiliconchemistry."^ Cu/Si Mixtureof SiCl4 + A allylsilanes Figure1.2. The Rochowprocessforpreparationoforganosiliconcompounds.
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