H2c C CH2CH 3 NO-cis and trans NO-cis and trans 1-Butene 2-isobutene H3C 3 CH H CH H 3 cis-2-butene trans-2-butene
H H H CH2 CH3 H3 C H CH3 H H3 C H3 C H H NO-cis and trans NO-cis and trans H3 C H H CH3 cis-2-butene trans-2-butene 1-Butene 2-isobutene
2.5 Alkynes: Compounds containing the carbon-carbon triple bond; Ethyne(Acetylene) and propyne Alkynes----hydrocarbons in which two carbon atoms Share three pairs of electrons between them, and are thus bonded by a triple bond, are called alkynes (s) H H H CH 3 H none Propyne Butyne (acetylene 1. it consists of linear molecules H 2. The bond angles of ethyne molecules are 180 180 180
2.5 Alkynes; Compounds containing the carbon-carbon triple bond; Ethyne (Acetylene) and propyne Alkynes----Hydrocarbons in which two carbon atoms Share three pairs of electrons between them, and are thus bonded by a triple bond, are called alkynes (炔烃） H H Ethyne (acetylene) H CH3 Propyne H Butyne H H 180 180 0 0 1. it consists of linear molecules 2. The bond angles of ethyne molecules are 180 0
2.6 Orbital Hybridization and the structure of alkynes H—三H 1)C----sp hybridization 2)Two sp orbitals 3)The remaining two 2p orbital are not hybridized to form pi-bonds π-bond H H H H H
2.6 Orbital Hybridization and the structure of alkynes H H 180 180 0 0 1) C----sp hybridization 2) Two sp orbitals 3) The remaining two 2p orbital are not hybridized to form pi-bonds H H H H H H H H -bond -bond
2.6A Bond Lengths of ethyne, ethene, and ethane The carbon-carbon triple bond is shorter than the carbon double bond and the carbon-carbon double bond is shorter th nan the carbon-carbon single bond 1)Ethyne-----C sp(50% S and 50% p 2)Ethene---C sp(25%S and 75%p) 3)Ethane----C sp(20%s and 80 %p) HH H H 1.20 1.05 H H 1.10
2.6A Bond Lengths of ethyne, ethene, and ethane The carbon-carbon triple bond is shorter than the carbon double bond, and the carbon-carbon double bond is shorter than the carbon-carbon single bond. 1) Ethyne-----C sp (50% s and 50% p) 2) Ethene----C sp2 (25% s and 75% p) 3) Ethane----C sp3 (20% s and 80 % p) H H H H H H H H H H H H 1.20 1.34 1.54 1.05 1.09 1.10
2.7 Benzene: A representative aromatic hydrocarbon *%k H H H Kekule structures or resonance hybrid PH phenyl group(苯基) CH2 C6HCH2( Benzyl group苄基)
2.7 Benzene: A representative aromatic hydrocarbon 芳烃 H H H H H H H H H H H H resonance hybrid Kekule structures or or phenyl group C6H5 - or PhCH2 or C6H5CH2 - ( Benzyl group 苄 基 ） (苯 基 ）