H HH H C Steric strain No steric strain Cis alkenes are less stable than their trans 9 isomers because of steric(spatial)strain between the two bulky substituents on the same side of the double bond
Organic Chemistry Organic Chemistry Xiamen Xiamen University University C C C H C H H H H H H H C C C C H H H H H H H H Steric strain No steric strain Cis alkenes are less stable than their trans isomers because of steric (spatial) strain between the two bulky substituents on the same side of the double bond
Heats of hydrogenation△H° u CH2 △H° Ho/Pd 116 kJ/mol CH CH3 CH? CH, CH2Ch CH Ho/Pd 120 kJ/mol H
Organic Chemistry Organic Chemistry Xiamen Xiamen University University Heats of hydrogenation Heats of hydrogenation ∆ H C C CH 3 H CH 3 H C C H CH 3 CH 3 H CH 3 C H 2 C H 2CH 3 H 2/P d H 2/P d ∆ H 116 k J / mol 120 k J / mol
9 Heats of Hydrogenation of Some Alkenes enes △H°( (kJ/mol HoC=CH2 137 CH3CHCH2 126 CH3 CH2CH=CH2 127 CiS CH3 CH=CHCH3 120 trans CH3 CH=CHCH3 116 ①D (CH3)C=CH2 119 (CH3)C=CHCH3 113 ⑨D (CH2)2C=CCH3)211
Organic Chemistry Organic Chemistry Xiamen Xiamen University University Heats of Hydrogenation of Some Alkenes H 2C C H 2 CH 3CH CH 2 CH 3CH 2CH CH 2 CH 3CH CHCH3 CH 3CH CHCH3 ci s tran s (CH3 ) 2C C H 2 (CH3 ) 2C C H C H3 (CH3 ) 2C C ( C H3 ) 2 137 126 127 120 116 119 113 111 A lkenes ∆ H (kJ /mol)
Antibonding C-C pi orbital (unfilled) Bonding C-H sigma orbital illed) C C Hyperconjugation The more substituents that are present ①D the more opportunities exist for hyperconjugation and the more stable the alkenes ⑨D
Organic Chemistry Organic Chemistry Xiamen Xiamen University University The more substituents that are present, the more opportunities exist for hyperconjugation and the more stable the alkenes Hyperconjugation
52烯烃的命名 Nomenclature of alkenes
Organic Chemistry Organic Chemistry Xiamen Xiamen University University 5.2 烯烃的命名 Nomenclature of Alkenes