3. Alkenes The nature of Organic reaction 烯烃:有机反应的种类
3. Alkenes : The Nature of Organic Reaction 烯烃:有机反应的种类
p91 3. 1 Naming Alkenes 1. Name the parent hydrocarbon, find the longest carbon chain that contains the double bond.命名母体 烯烃 2. Number the carbon atoms in the chain给主链碳原子编号 3. Write the full name给出完整的命名
3.1 Naming Alkenes 1. Name the parent hydrocarbon, find the longest carbon chain that contains the double bond. 命名母体 烯烃 2. Number the carbon atoms in the chain 给主链碳原子编号 3. Write the full name 给出完整的命名 p.91
CHr CH,CHCH=CHCH ( CH3hCHCH=CHCH2 CH3 2-己烯 2甲基3-己烯 2-hexene 2-methyI-3-hexene CH 5-甲基-1,3-环己二烯环戊烯 5-methyl-1, 3-cyclohexadiene cyclopentene
5-甲基-1,3-环己二烯 环戊烯 CH3 2-hexene 2-methyl –3-hexene 5-methyl –1,3-cyclohexadiene cyclopentene CH3CH2CH2CH CHCH3 (CH3 )2CHCH CHCH2CH3 2-己烯 2-甲基-3-己烯
CH=cH- CH CH=CH-- CH=CHCH 乙烯基 丙烯基 烯丙基 p92 Ⅴ inyl group Propanol Allyl group rou HC= CH3-CH= (CHbC= 亚甲基亚乙基 亚异丙基 Methylene Ethylene Isopropylene 0 CHCOH 2-(或αx-)亚环戊基环戊酮亚3-环己烯基乙酸
CH2 CH CH3CH CH2 CH2 CHCH2 乙烯基 丙烯基 烯丙基 Vinyl group Propanyl group Allyl group H2C CH3 CH (CH3 )2C 亚甲基 亚乙基 亚异丙基 2-(或a-)亚环戊基环戊酮 亚-3-环己烯基乙酸 O CHCO2H Methylene Ethylene Isopropylene p.92
Many alkenes are known by Common names H2C=CH 2 Ethylene =ethene H2C=CH Propylene= propene H3C CH Isobutylene=2- methylpropene C=CH2 CH3 Isoprene=2-methyl-1, 3- H3C C、CH2 butadiene H2C C
Many Alkenes Are Known by Common Names • Ethylene = ethene • Propylene = propene • Isobutylene = 2- methylpropene • Isoprene = 2-methyl-1,3- butadiene
3.2 Electronic structure of alkenes 烯烃的电子结构 0.109nmH HH 0.13nm C116.7° H 1216°
3.2 Electronic structure of alkenes 烯烃的电子结构 H C C H H H C C H H H H 0.133nm 0.109nm 116.7° 121.6° p.11
Rotation of n bond is prohibitive C 90 rotation bond Broken m bond after rotation (p orbitals are parallel) (p orbitals are perpendicular
Rotation of p Bond Is Prohibitive
p91 3. 3 cis-trans isomers of alkenes 烯烃的顺一反异构体
3.3 cis-trans isomers of Alkenes 烯烃的顺―反异构体 p.91
CH3 CH3 The presence of a carbon carbon double can create two C-c possible structures cis isomer -two similar cis-2-Butene groups on same side of the ouble bond trans isomer similar groups on opposite sides H CH3 Each carbon must have two different groups for CH these(cis/trans ) isomers to trans-2-Butene occur
• The presence of a carboncarbon double can create two possible structures – cis isomer - two similar groups on same side of the double bond – trans isomer similar groups on opposite sides • Each carbon must have two different groups for these(cis/trans) isomers to occur
Cis-Trans Isomers Require That End 91 Groups must differ in pairs Bottom pair cannot D B C-C be superposed(重B D A 叠)by D B 180° rotation C=CX C=C B without breaking E A E C=C
Cis-Trans Isomers Require That End Groups Must Differ in Pairs Bottom pair cannot be superposed (重 叠) by 180° rotation without breaking C=C X p.91