Constitution and Nomenclature

In contrast to the relatively unreactive alkanes, alkenes and alkynes are chemically reactive because they have double and triple carbon-carbon bonds as functional groups. In the lUPAC nomenclature the names of alkenes end with the suffix -ene and the position of the double bond is labeled by number of the C-atom on which this double bond begins. In analogy with alkanes with branched chains, the root of the word is the name of the longest chain of C-atoms and the atom numbering is arranged 

Vancik, Basic Organic Chemistry for the Life Sciences, 

SO that C-atom with the double bond has the smallest possible number. The rules for naming alkynes are the same as for alkenes with the exception that the suffix is -yne. 

Cumulenes with ten or more cumulated carbon atoms have been detected in the interstellar space and some theories propose that such molecules played very important role in the formation of organic molecules during chemical evolution. 

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The following examples Illustrate the constitution and nomenclature of these salts —... 

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