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1、Lesson2OrganicChemistryThenatureofOrganicChemistryhaschangedgreatlysince1828.Beforethattimethescientificphilosophyknownas“Vitalism”maintainedthatOrganicChemistrywasthechemistryoflivingsystems.Itmaintainedthatorganiccompoundscouldonlybeproducedwithinlivingmatterwhileinorganiccompoundsweresynthesi
2、zedfromnon-livingmatter.Eventheword“organic”comesfromthesamerootastheword“organism”or“organ”.HoweverpeoplelikeProfessorWohlerbeginningin1828determinedthatitwasindeedpossibletosynthesizeorganiccompoundsfromthosecompoundsthatwereconsideredinorganic.Oneofthefirstorganiccompoundssynthesizedfrombasic
3、allyinorganiccompoundswasthecompoundUreawhichisametabolicproductofurine.ItwassynthesizedfromAmmoniumCyanateconsideredacompoundproducedoutsideoflivingmatterandthereforeconsideredinorganic.SincethenmanymillionsofOrganiccompoundshavebeensynthesized“invitro”inotherwordsoutsidelivingtissue.1Structura
4、lformulasThebuildingblockofstructuralorganicchemistryisthetetravalentcarbonatom.Withfewexceptions,carboncompoundscanbeformulatedwithfourcovalentbondstoeachcarbon,regardlessofwhetherthecombinationiswithcarbonorsomeotherelement.Thetwo-electronbond,whichisillustratedbythecarbon-hydrogenbondsinmetha
5、neorethaneandthecarbon-carbonbondinethane,iscalledasinglebond.Intheseandmanyrelatedsubstances,eachcarbonisattachedtofourotheratoms:Thereexist,however,compoundssuchasethene(ethylene),C2H4,inwhichtwoelectronsfromeachofthecarbonatomsaremutuallyshared,therebyproducingtwotwo-electronbonds,anarrangeme
6、ntwhichiscalledadoublebond.Eachcarboninetheneisattachedtoonlythreeotheratoms:Similarly,inethyne(acetylene),C2H2,threeelectronsfromeachcarbonatomaremutuallyshared,producingthreetwo-electronbonds,calledatriplebond,inwhicheachcarbonisattachedtoonlytwootheratoms:Byconvention,asinglestraightlineconne
7、ctingtheatomicsymbolsisusedtorepresentasingle(two-electron)bond,twosuchlinestorepresentadouble(four-electron)bond,andthreelinesatriple(six-electron)bond.Representationsofcompoundsbythesesymbolsarecalledstructuralformulas;som
