Chapter 8 Alkenes and alkynes l Properties and synthesis 8.1 Introduction Alkenes are hydrocarbons whose molecules contain the carbon -carbon double sonde ethylene Hydrocarbons whose molecules contain the cardencicarbonsteiple abond arengalled alkynes
Chapter 8 Alkenes and alkynes I. Properties and synthesis 8.1 Introduction Alkenes are hydrocarbons whose molecules contain the carbon-carbon double bond. Hydrocarbons whose molecules contain the carbon-carbon triple bond are called alkynes. C C H H H H Ethene or ethylene HC CH or acetylene or ethyne
8.2 Nomenclature of alkenes and cycloalkenes H2C-C CH3 IUPAC Propene common; Propylene H2c=C—cH IUPAC: 2-MethylPropene Common; Isobutylene CH C vcIohexane Cyclohexene 相应的烷-ane变成烯-ene
8.2 Nomenclature of alkenes and cycloalkenes H2 C C H CH3 IUPAC: Propene common; Propylene H2 C C CH3 CH3 IUPAC: 2-MethylPropene Common; Isobutylene Cyclohexane Cyclohexene 相 应 的 烷 -ane变 成 烯 -ene
The IUPAC rules for naming alkenes are similar in many respects to those for naming alkanes Selecting the longest chain that contains the double bond 2. Number the chain 23 234 6 H2C=CHCH2 CH3 CH3CH=CHCH2 CH2CH3 32 654321 1-Butene 2-Hexene (not 3-butene) (not 4-hexene
The IUPAC rules for naming alkenes are similar in many respects to those for naming alkanes 1. Selecting the longest chain that contains the double bond 2. Number the chain H2 C CHCH2 CH3 1-Butene (not 3-butene) 1 2 3 4 4 3 2 1 CH3 CH=CHCH2 CH2 CH3 1 2 3 4 5 6 6 5 4 3 2 1 2-Hexene (not 4-hexene)
3. Indicate the locations of the substituent groups CH CH 3 H3C—c=cHcH2CH3 CH2 C=CHCH CHCH 12345 123456 2-Methy1-2-pentene 2, 5-Dimethyl-2-hexene (not 4-Methyl-3-pentene) (not 2, 5-Dimethyl-4-hexene) CH3 H3C—c=cHcH2C—cH3 CHCH=CHCHbCI 4321 5, 5-Dimethyl-2-hexene 1-Chloro-2-butene (not 2, 2-Dimethyl-4-hexene) (not 4-chloro-2-butene)
3. Indicate the locations of the substituent groups C CHCH2CH3 2-Methyl-2-pentene (not 4-Methyl-3-pentene) CH3C=CHCH2CHCH3 1 2 3 4 5 6 2,5-Dimethyl-2-hexene (not 2,5-Dimethyl-4-hexene) CH3 H3C 1 2 3 4 5 CH3 CH3 C H CHCH2C 5,5-Dimethyl-2-hexene (not 2,2-Dimethyl-4-hexene) CH3CH=CHCH2Cl 4 3 2 1 1-Chloro-2-butene (not 4-chloro-2-butene) H3C 1 2 3 4 5 6 CH3 CH3 CH3
4. Number substituted cycloalkenes in the way that gives the carbon atoms of the double bond the 1-and 2 positions and that also gives the substituent groups the lower numbers at the first point of difference 1- Methylcyclopentane(1-甲基环戊烯)35 Dimethylcyclohexene(3,5二甲基环己烯) (not 2-methylcyclopentene) (not 4, 6-Dimethylcyclohexene)
4. Number substituted cycloalkenes in the way that gives the carbon atoms of the double bond the 1- and 2- positions and that also gives the substituent groups the lower numbers at the first point of difference 1-Methylcyclopentene (1-甲 基 环 戊 烯 ） (not 2-methylcyclopentene) 1 2 3 3,5-Dimethylcyclohexene (3,5-二 甲 基 环 己 烯 ） (not 4,6-Dimethylcyclohexene) 1 2 3 4 5
5. Two frequently encountered alkenyl groups are the vinyl group and the allyl group H2c C=g—c H3C—Hc=c The vinyl group团乙烯基) The ally group(烯丙基) The Propylene group两丙烯基) CH2Cl -CH2Br IUPAC: Bromoethene IUPAC: 3-Chloropropene IUPAC: 3-Bromopropene Common; vinyl bromide Common; allyl chloride Common; allyl bromide (乙烯基溴) (烯丙基氯) (烯丙基溴)
5. Two frequently encountered alkenyl groups are the vinyl group and the allyl group. The vinyl group (乙 烯 基 ） The ally group (烯 丙 基 ） H2C C H H2C C H CH2 HC C H2 H3C The Propylene group (丙 烯 基 ） Br CH2Cl IUPAC: Bromoethene Common; vinyl bromide (乙烯 基 溴 ） IUPAC: 3-Chloropropene Common; allyl chloride (烯 丙 基 氯 ） CH2 Br IUPAC: 3-Bromopropene Common; allyl bromide (烯 丙 基 溴 ）
6. Designate the geometry of a double bond of a disubstituted alkene with the prefixes cis and trans Cl H Cl is-1. 2-Dichloroethene trans-1. 2-Dichloroethene How to do? F
6. Designate the geometry of a double bond of a disubstituted alkene with the prefixes cisand transCl H Cl H Cl H H Cl cis-1,2-Dichloroethene trans-1,2-Dichloroethene Br H Cl F How to do?
8.2A The(E)-(Z)System for designation alkene diastereomers Higher priority Br Higher priority H Higher priority (Z)-2-Bromo-1-chloro-1-floroethene (E)-2-Bromo-l-chloro-l-floroethene Higher priority H3C CH3 Higher priority、HaC CH3 >H CH3 Higher priority Z-2-Butene E)-2-Butene (cis)-2-Butene (trans)-2-Butene
8.2A The ( E )-( Z ) System for designation alkene diastereomers Br H Cl F (Z)-2-Bromo-1-chloro-1-floroethene H Higher priority igher priority Br H F Cl (E)-2-Bromo-1-chloro-1-floroethene Higher priority H3C H CH3 H (Z)-2-Butene (cis)-2-Butene Higher priority Higher priority H3C H H CH3 (E)-2-Butene (trans)-2-Butene Higher priority CH3 H
Higher priority Cl Cl B (E)-1-Bromo-1s2-dichloroethene (Z)-1-Bromo-1, 2-dichloroethene (cis)-2-Bromo-1, 2-dichloroethene (trans )-2-Bromo-1, 2-dichloroethene (HHH) Higher priority H3C、 CH3 H3C CH2CH3 CH H CH2CH 3 CH3 CH3CH2> CH3 (CHH) E)-3-Methyl-2-pentene (2-3-Methyl-2-pentene (cis)-3-Methyl-2-pentene (trans )-3-Methyl-2-pentene
Cl H Cl Br (E)-1-Bromo-1,2-dichloroethene (cis)-2-Bromo-1,2-dichloroethene Higher priority Cl H Br Cl Cl H Br Cl (Z)-1-Bromo-1,2-dichloroethene (trans)-2-Bromo-1,2-dichloroethene H3C H CH3 CH2CH3 (E)-3-Methyl-2-pentene (cis)-3-Methyl-2-pentene Higher priority H3C H CH2CH3 CH3 CH3 H (HHH) (CHH) (Z)-3-Methyl-2-pentene (trans)-3-Methyl-2-pentene CH3CH2 CH3
8. 3 Nomenclature of alkynes 8.3A IUPAC Nomenclature Unbranched alkynes, for example, are named by replacing the -ane of the name of the corresponding alkane with the ending -yne. The chain is numbered in order to give the carbon atoms of the triple bond the lower possible numbers
8.3 Nomenclature of alkynes 8.3A IUPAC Nomenclature Unbranched alkynes, for example, are named by replacing the –ane of the name of the corresponding alkane with the ending –yne. The chain is numbered in order to give the carbon atoms of the triple bond the lower possible numbers