Which of the following alkenes can have both cis and trans isomers?
I. Propene
II. 2-methyl-2-butene
III. 4-Methyl-2-pentene

Question

Quizplus · Accepted Answer

For a compound to have cis and trans isomers, it must have two different substituents on each carbon of the pi bond. Propene only has one substituent on each carbon, so it cannot have cis and trans isomers. 2-methyl-2-butene has a symmetric methyl group on each carbon of the pi bond, so it also cannot have cis and trans isomers. However, 4-methyl-2-pentene has a methyl group and a hydrogen on each carbon of the pi bond, allowing for the possibility of cis and trans isomers.

Which of the Following Alkenes Can Have Both Cis and Trans