有机化学英文教学课件chapter8.ppt

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1、OrganicChemistryWilliamH.BrownChristopherS.FooteBrentL.IversonHaloalkanesChapter8StructureHaloalkane(alkylhalide):acompoundcontainingahalogencovalentlybondedtoansp3hybridizedcarbon;giventhesymbolRXHaloalkene(vinylichalide):acompoundcontainingahalogenbondedtoansp2hy

2、bridizedcarbonHaloarene(arylhalide):acompoundcontainingahalogenbondedtoabenzenering;giventhesymbolArX(wedonotstudyvinylicorarylhalidesinthischapter)Nomenclaturenumbertheparentchaintogivethesubstituentencounteredfirstthelowestnumber,whetheritishalogenoranalkylgroupi

3、ndicatehalogensubstituentsbytheprefixesfluoro-,chloro-,bromo-,andiodo-,andlisttheminalphabeticalorderwithothersubstituentslocateeachhalogenontheparentchainbygivingitanumberprecedingthenameofthehalogeninhaloalkenes,numbertheparentchaintogivecarbonatomsofthedoublebon

4、dthelowersetofnumbersNomenclatureexamplesCommonnames:namethealkylgroupfollowedbythenameofthehalideNomenclatureseveralpolyhaloalkanesarecommonsolventsandaregenerallyreferredtobytheircommonortrivialnameshydrocarbonsinwhichallhydrogensarereplacedbyhalogensarecommonlyn

5、amedasperhaloalkanesorperhaloalkenesDipoleMomentsDipolemomentofRXdependson:thesizesofthepartialchargesthedistancebetweenthemthepolarizabilityoftheunsharedelectronsonhalogenvanderWaalsForcesHaloalkanesareassociatedintheliquidstatebyvanderWaalsforcesvanderWaalsforces

6、:agroupintermolecularattractiveforcesincludingdipole-dipoleforcesdipole-induceddipoleforcesinduceddipole-induceddipole(dispersion)forcesvanderWaalsforcespullmoleculestogetherasmoleculesarebroughtcloserandcloser,vanderWaalsattractiveforcesareovercomebyrepulsiveforce

7、sbetweenelectroncloudsofadjacentatomsormoleculesvanderWaalsForcestheenergyminimumiswheretheattractiveforcesarethestrongestnonbondedinteratomicandintermoleculardistancesattheseminimacanbemeasuredbyx-raycrystallographyandeachatomandgroupofatomscanbeassignedavanderWaa

8、lsradiusnonbondedatomsinamoleculecannotapproacheachothercloserthanthesumoftheirvanderWaalsradiiwithoutcausingnonbondedinteractionstrainBoilingPoi