Synthesis and derivation of chlorofunctionalized organosilicon polymers via acyclic diene metathesis polymerization

115 Pages·1997·4.3 MB·English

by  Cummings, Sophia Kay

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.