Basic Organic Nomenclature

An Introduction

Dave Woodcock,
Associate Professor Emeritus UBC (Okanagan)
©1996,2000, 2008

4. Functional Groups with Suffix Only

III. Alkenes (i)

Index


The -ene name is given to the C,C double bond function. Like the -yne function, the double bond may appear anywhere in the chain of carbon s and so requires a position identifier. Study the following simple examples of the alkene family, given with their names and models:

Alkene StructureIUPAC NameModel
ethene
propene
but-1-ene
methylpropene
pent-1-ene
hex-1-ene
2-methylpent-2-ene
2,3-dimethylbut-2-ene
cyclopentene
cyclohexene

Note from the above names that the locant is only the first number of the two which identify the position of the double bond, exactly paralleling the situation with the triple bond already studied. Thus although the double bond in hex-1-ene is between carbons numbered 1 and 2 in the chain, only the first is required to position the double bond, the second being understood to be the next higher number.
This observation requires that the double bond be included in the main chain that is used for the root name.

Notice also the positioning of the locant, immediately prior to the group it is positioning.

Part 2 of Alkenes: Naming alkene stereoisomers
Review Alkynes.

Next page : Functional Groups with Suffix or Prefix. I.

Index


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