Chapter 7 Alkenes and Alkynes I: Properties and Synthesis Elimination Reactions of Alkyl Halides
Chapter 7 Alkenes and Alkynes I: Properties and Synthesis. Elimination Reactions of Alkyl Halides
ORGANIC CHEMISTRY Chapter 7 7.1 Introduction Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 7.1 Introduction
ORGANIC CHEMISTRY Chapter 7 e Alkenes are hydrocarbons whose molecules contain the carbon-carbon double bond g alkynes are hydrocarbons whose molecules contain the carbon-carbon triple bond -一 H H CH C-C H H H Ethene(ethylene) opene Alkenes(olefins) H-C≡C-H Ethyne (acetylene) Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 Alkenes are hydrocarbons whose molecules contain the carbon-carbon double bond. Alkynes are hydrocarbons whose molecules contain the carbon-carbon triple bond. C C H H H H C C CH3 H H H Ethene (ethylene) Propene Alkenes (olefins) H C C H Ethyne (Acetylene)
ORGANIC CHEMISTRY Chapter 7 7. 2 The(E(b System for Designating Alkenes diastereomers Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 7.2 The (E)–(Z) System for Designating Alkenes Diastereomers
ORGANIC CHEMISTRY Chapter 7 Cis-Trans Isomerism in alkenes CH3 CH CH 3 Sc=c cis-2-Butene tranS-2-Butene The E Z Designation H CI Br H Br H (E)-1-Bromo-2-chloro-Butene (2r-1-Bromo-2-chloro-Butene Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 Cis-Trans Isomerism in Alkenes Cis-Trans Isomerism in Alkenes C C CH3 H CH3 H C C H CH3 CH3 H cis-2-Butene trans-2-Butene The E, Z Designation The E, Z Designation C C H Br Cl H C C Br H Cl H (E)−1−Βromo-2-chloro−Butene (Z)−1−Βromo-2-chloro−Butene
ORGANIC CHEMISTRY Chapter 7 7.3 Relative stabilities of alkenes Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 7.3 Relative Stabilities of Alkenes
ORGANIC CHEMISTRY Chapter 7 7.3A Heats of Hydrogenation Pt C=C、+H-H C-C H°=120kJ/mol HH CH H △H° Ho/Pt 115 kJ/mol CH CH CH2 CHChoCh CH H/Pt 120 kJ/mol H Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 7.3A Heats of Hydrogenation C C + H H Pt C C H H ∆H°≅ 120 kJ / mol C C CH3 H CH3 H C C H CH3 CH3 H CH3CH2CH2CH3 H2/Pt H2/Pt ∆H -115 kJ/mol -120 kJ/mol
ORGANIC CHEMISTRY Chapter 7 Heats of Hydrogenation of Some Alkenes Alkenes △H°( kJ/mol) H2C=CH2 137 CHCH=CH 12 127 CH3 CH2CH=CH2 -128 cis-Ch2CH-CHCH 120 trans - ChCH-CHCH -115 (CH3)=CH2 -119 (CH3)2C=CHCH3 -113 (CH3)2C=C(CH3)2 111 Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 Heats of Hydrogenation of Some Alkenes H2C CH2 CH3CH CH2 CH3CH2CH CH2 CH3CH CHCH3 CH3CH CHCH3 cistrans- (CH3)2C CH2 (CH3)2C CHCH3 (CH3)2C C(CH3)2 -137 -127 -128 -120 -115 -119 -113 -111 Alkenes ∆H (kJ/mol)
ORGANIC CHEMISTRY Chapter 7 7. 3B Relative stabilities from heats of Combustion Heats of Combution of some Alkenes Alkenes AH°(kJ/mo) CH2CHCH-CH 2719 CIS-CH3 CH=CHCH3 2712 trans-CH3CH=CHCH3 2707 CH3hC=Ch 2703 Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 7.3B Relative Stabilities from Heats of Combustion CH3CH2CH CH2 CH3CH CHCH3 CH3CH CHCH3 cistrans- (CH3)2C CH2 -2719 -2712 -2707 -2703 Alkenes ∆H (kJ/mol) Heats of Combution of Some Alkenes
ORGANIC CHEMISTRY Chapter 7 Alkene Stability CH3 Acid CH3 CH H ch, catalyst h trans 76% CIs 24% cis-2-Butene is less stable than trans 2-butene at room temperature Relative Stabilities (CH3)2C=CH2> trans-CH3 CH=CHCH3 CIS-CH3 CH=CHCH3 CH3,CH-CH, Department of Chemistry, Xiamen University
ORGANIC CHEMISTRY Department of Chemistry, Xiamen University Chapter 7 Alkene Stability C C CH3 H CH3 H cis C C H CH3 CH3 H trans Acid catalyst 76% 24% cis-2-Butene is less stable than trans-2-butene at room temperature. Relative Stabilities CH3CH2CH CH2 CH3CH CHCH3 CH3CH CHCH3 (CH trans- cis- 3)2C CH2 > > >