Page 89 - Pharm.Org.Chem-I 02-06-05-101

Try yourself

Q1: Give the structures of the following alkenes:
• (Z)-2-chloro-2-butene.
• 2-Methyl-1-pentene.
• (E)-2-Pentene.
• (Z)-3-Hexene
Q2: indicate if cis/trans isomers are possible for the
following and draw the isomers:

a. 1-pentene

b. 2-hexene

Relative stability of alkenes

The greater the number of attached alkyl groups (i.e., the more highly substituted the

carbon atoms of the double bond), the greater is the alkene’s stability, due to

hyperconjugation (The number of canonical structures = number of α hydrogens + 1).

 CH2
C
H_______ CH3 H2C H
CH3
C C
H


H3C

7 canonical structures exist 3 canonical structures exist
more stable less stable

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