Question

which step in naming unsaturated hydrocarbons is used for alkenes but not alkynes? identify the longest chain of carbon atoms. examine the multiple bond for cis - and trans - isomers. number the chain of carbons, starting with the end nearest the multiple bond. add a number prefix indicating the first carbon atom in the multiple bond.

Explanation:

Alkenes can have cis - trans isomerism due to restricted rotation around the double - bond. Alkynes have a linear geometry around the triple - bond and do not exhibit cis - trans isomerism. The other steps are common to both alkenes and alkynes in naming.

Answer:

Examine the multiple bond for cis - and trans - isomers.