2.3 Alkenes: Compounds containing the carbon-carbon double bond------Ethene and Propene Hydrocarbons whose molecules contain a carbon-carbon double bond are called alkenes. Ethene (ethylene)and Propene(propylene) H H H H H CH3 Ethene Propene 1. The six atoms of ethene are coplanar 18 2. Bond angles is triangular H 121 Fig. The structure and bond angles of ethene
2.3 Alkenes: Compounds containing the carbon-carbon double bond------Ethene and Propene Hydrocarbons whose molecules contain a carbon-carbon double bond are called alkenes. Ethene (ethylene) and Propene (propylene) H H CH3 H H H H H Ethene Propene H H H H 121 118 0 0 1. The six atoms of ethene are coplanar 2. Bond angles is triangular Fig. The structure and bond angles of ethene
2.4 Orbital Hybridization and Structure of Alkenes 1)C----SPz-Hybridized carbon atoms 2)One 2p orbital is left unhybridized 3)How to form pi-bond?
2.4 Orbital Hybridization and Structure of Alkenes 1) C----SP2 -Hybridized carbon atoms 2) One 2p orbital is left unhybridized 3) How to form pi-bond ?
2.4A Restricted rotation and the double bond 121 Fig. The structure and bond angles of ethene Rotation Rotate90° H Fig 2.9 Rotation of a carbon atom of a double bond through an angle of 90 results in the breaking of the t bond
2.4A Restricted rotation and the double bond H H H H 121 118 0 0 Fig. The structure and bond angles of ethene H H H H H H H H Rotation Rotate 90 0 Fig 2.9 Rotation of a carbon atom of a double bond through an angle of 90 results in the breaking of the bond 0
24BCis- Trans isomerism顺反异构 H H H NO Cis-trans Cis Cis-1.2-dichloroethene H H C NO CiS-trans Trans Trans-1.2-dichloroethene
2.4B Cis-Trans isomerism 顺 反 异 构 H H H H NO Cis-trans Cl H Cl H Cl H H Cl Cis Trans Cis-1,2-dichloroethene Trans-1,2-dichloroethene Cl H Cl H Cl H H Cl Cl Cl H H NO Cis-trans
H cis-1. 2-Difluoroethene trans-1.2-Difluoroethene F F Cl C cis-1. 2-Dichloro-12-difluoroethene tranS-1. 2-Dichloro-1 2-difluoroethene Note; cis-trans isomerism of this type is not possible if one carbon atom of the double bond bears two identical groups b
F H F H F Cl F Cl F H H F cis-1,2-Difluoroethene trans-1,2-Difluoroethene F Cl Cl F cis-1,2-Dichloro-1,2-difluoroethene trans-1,2-Dichloro-1,2-difluoroethene Note; cis-trans isomerism of this type is not possible if one carbon atom of the double bond bears two identical groups. a a a b a b d d