Names of Alkenyl Groups

As in the nomenclature of alkanes, many groups derived from alkenes have common names. Three of the most often encountered are the vinyl, allyl, and isopropenyl groups. 

The lUPAC rules for naming alkenes are similar to those for alkanes, but the position of the double bond in the chain and the geometric arrangement of subsdments around the double bond must be indicated. As in the case of some simple alkyl groups, a few common names are allowed as part of an lUPAC name, including vinyl, allyl, and isopropenyl. 

The longest continuous chain of carbon atoms that contains the double bond is the 

There are eight carbons in this chain, so it is an octene. 

If the atoms directly attached to the carbon atom of the double bond have the same atomic number, the second, third, and farther atoms are considered until a difference is found. Then apply rule 1. 

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