Organic Formulation Theory: Alkenes

Hydrocarbons with double bonds, Olefins or Alkenes.

They are hydrocarbons having one or more double bonds between the carbon atoms. The general formula with a single double bond is C_nH_2n.

Alkenes with one double bond.

They are named according to the following rules:

• The longest chain containing the double bond is chosen and the ane end is replaced by ene.
• The chain is numbered from the double bond closest to the end. This locator is the smallest of the two numbers that correspond to the two carbon atoms connected by the double bond.
• The position of the double bond or unsaturated is indicated by the corresponding locator standing in front of the name.

Example:

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Pent-2-ene

• If there are radicals, it is taken as the longest backbone of the double bond-containing chain. The numbering is performed such as the carbon atom with double bond corresponds the lowest possible locator. The radicals are named like alkanes.

Example:

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4,5-dimethylhex-2-ene

Alkenes with several double bonds.

• When a hydrocarbon contains more than one double bond we used the following endings to name them: -diene, -triene, etc., instead of the termination ene. The chain is numbered assigning double bond carbons with lower locators that can be possible.

Example:

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Hepta-2,4-diene

• If the compound contains radicals, these are named as alkanes, choosing as the hydrocarbon backbone the one that contains the largest number of double bonds, though it is not the longest one.

Example:

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2-ethyl-3-methylhexa-1,3,4-triene

Univalent radical derived from alkenes linear.

They are obtained from alkenes by lossing of a hydrogen atom from a terminal carbon. In the numbering of the radical, the free valence carbon (by lossing of the hydrogen atom) receives the number 1. They are namee prefixing the corresponding number prefix to completion enyl.

Examples:

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You can download the App BioProfe READER to practice this theory with self-corrected exercises.