《有机化学》英文教学课件：Chap 3 Alkene (2012).ppt

《《有机化学》英文教学课件：Chap 3 Alkene (2012).ppt》由会员上传分享，免费在线阅读，更多相关内容在教育资源-天天文库。

1、Chapter3AlkeneandAlkyneNotallhydrocarbonshavetheformulaCnH2n+2.ThereisanotherfamilyofhydrocarbonsthathaveformulaCnH2n,inwhichtheycontaincarbon-carbondoublebonds.Theyarecalledalkenes.1TherearealsohydrocarbonsoftheformulaCnH2n-2,whosechemicalpropertiesresemblethoseofthealkenesbutnotthoseoft

2、healkanes.Thesecompoundsarethealkynes.Thestructuresandsomeofthepropertiesofthefamiliesofunsaturatedhydrocarbon,calledalkenesandalkynes,arediscussedinthischapter.2Eachcarbonatominethyleneisnotattachedtofourotheratomsasinmethane,buttothree.Section1AlkeneⅠ.Structureofethylene(C2H4)3Inhybridi

3、zationtheory,sp2hybridizationcreatethreenewhybridorbitals,whichdoabetterjobofattachingthecarbonatomtothethreehydrogensthandothepureatomicorbitals.So,let’scombinethecarbon2s,2px,and2pyorbitalstoproducethreenew,sp2hybrids.The2pzunhybridized.sp22p2s2p4sp2Hybridorbital56Thecarbonsp2hybridover

4、lapthesp2hybridofanothercarbontoformabond,C-Cbond.Therestoffourcarbonsp2hybridsoverlapfourhydrogen1sorbitalstogivefourC-Hbonds.Allthefivebondsareinthesameplane.C-CbondC-Hbond7structureofethylene8Twounhybidized2pzorbitalsparallelandoverlapeachothertoformorbitalwhichplumbtotheplanecomb

5、inedbythefivebonds.9ethene1011Ⅱ.Isomerism1)carbon-chainisomerismC4H8:CH3CH2CHCH2CH3CCH2CH31-butene2-methyl-1-propene122)positionalisomerism1-buteneCH3CH2CHCH2CH3CHCHCH32-buteneC4H8:133)cis-transisomerismcis-2-butenetrans-2-buteneDisubstitutedalkenesmayexistasapairofconfigurationalstereoi

6、somers,oftendesignatedcisandtrans.14Theessentialrequirementforthisstereo-isomerismisthateachcarbonofthedoublebondmusthavetwodifferentsubstituentgroups(onemaybehydrogen).15IsomerismandMedicine:inefficacyDiethylstilbestrolorStilbestrol(post-contraceptive)（己烯雌酚）16Ⅲ.Nomenclature(IUPAC)1.Namin

7、gofalkeneswithoutcis-transisomerism1)Searchforthelongestchainofcarbonscontainingadoublebond,whetherornotitisalsothelongestchaininthemolecule.Acommon"ene"suffixidentifiesthesecompoundsasalkenes.17Whenmoleculecontainmorethanonedoublebondtheyarenamedas‘dienes,’‘trienes