最新《聚合反应原理专论》 chapter5 （中科大研究生教学课件教学讲义ppt.ppt

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1、《聚合反应原理专论》chapter5（中科大研究生教学课件）5-1Theconceptofaddition-fragmentationchaintransferreactionRelativelyeasyruptureofacarbon-sulfurbondinxanthatesSRHowtoapplythisorganicreactioninthepolymerizationIncreaseamountofvinylmonomeranddecreasetheamountoftransferagentforinitiatingmonomertopolymer

2、ize.Decreasetheamountofinitiatortoavoidtheadditiontosulfurdirectly.Increasethestabilityofstableradical.5-2DesignandsynthesisofchaintransferagentCt=ktr/kp,forcontrolledradicalpolymerization,Ct>2.Whenterminationisneglected,PDI=1+1/Ct.SDesignofchaintransferagenta.ZgroupsinvestigatedOrd

3、erofchaintransferconstant:Zgroup:Ph>PhCH2S~CH3->N-Pyrrolo>OC2H5b.TheeffectofRgrouponchaintransferconstantBasedonRAFTpolymerizationofMMAat60oC,Thedecreaseorderofchaintransferconstantisasfollows:Rgroup:-C(alkyl)2CN~-C(Me)2Ar>-C(Me)2(C=O)O(alkyl)>C(Me)2(C=O)NH(alkyl)>-C(Me)HPh>-C(Me)3~

4、-CH2PhOnlyforR=-CMe2Phand–CMe2CN(Ct>20),RAFTpolymerizationofMMAiscontrolled.Designprinciplesofchain-transferagentsZisphenylRgroupsarebenzyl,ester,nitrile,etc,thusitisagoodleavinggroupcomparingwithpolymerchainradical.Forexample2.SynthesisofRAFTagents1)Synthesisofdithioester(1)Fromdit

5、hocarboxylateSSSa.b.GrignardreactionTHFassolventisbetterthenEt2OSometimesRClisbetterthanRBrAdditionofCuBrinGrignardreactionsystemenhancedtheyieldofdithioestersc.ThereactionofsulfurinalkalineconditionSubstituentsonphenylgroupdonotaffectthereaction.(2)ReactionsofdithiocarboxylicacidMa

6、rkovnikov’srolea.Additionreactionwitholefinb.ReactionwithRXc.Reactionwithinitiators(3)ReactionofRSH(4)Friedel-CraftsreactionThiscanbesynthesizedbythereactionofRHandC(S)Cl2toformRSC(S)Cl,theFriedel-craftsreaction.2)Synthesisofdithiocarbonate3)RAFTreagentwithheterocyclicgroupCS5-3Mech

7、anismofpolymerization1.InitiationRAFTagentsfunctioneffectivelyonlywhenthesubstituentRonsulfurisagoodhomolyticleavinggroup,suchasbenzylgroup,whencomparedtothepolymerchainPn.2.Propagationreactions3.PossibleterminationreactionsInitialradicals,R.Propagationradicals,Pn.Intermediateradica

8、lsCoupleordispropor