Substituent

In organic chemistry, a substituent is an atom or group of atoms substituted in place of a hydrogen atom on the parent chain of a hydrocarbon. The suffix -yl (meaning "attached to") is used when naming organic compounds that contain a substituent. Additionally, when naming hydrocarbons that contain a substituent, positional numbers are used to indicate which carbon atom the substituent is attached to when such information is needed to distinguish between structural isomers.

Related Topics:
Organic chemistry - Hydrogen - Parent chain - Hydrocarbon - Organic compound - Isomer

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The phrases most-substituted and least-substituted are frequently used to describe molecules and predict their products. For example:

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• Markovnikov's rule predicts that the hydrogen adds to the carbon of the alkene functional group that has the greater number of hydrogen substituents.
• Zaitsev's rule predicts that the major reaction product is the alkene with the more highly substituted (more stable) double bond.