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Substitution reaction - Wikipedia, the free encyclopedia (215 words) |
 | In organic chemistry, the electrophilic and nucleophilic substitution reactions are of prime importance. |
| Organic substitution reactions are classified in several main organic reaction types depending on whether the reagent that brings about the substitution is considered an electrophile or a nucleophile, whether a reactive intermediate involved in the reaction is a carbocation, a carbanion or a free radical or whether the substrate is aliphatic or aromatic. |
| Electrophiles are involved in electrophilic substitution reactions and particularly in electrophilic aromatic substitutions. |
| Aromatic Reactivity (2788 words) |
| The chemical reactivity of benzene contrasts with that of the alkenes in that substitution reactions occur in preference to addition reactions, as illustrated in the following diagram (some comparable reactions of cyclohexene are shown in the green box). |
| This does not significantly affect the nitration reaction (note the presence of sulfuric acid as a dehydrating agent), but sulfonation is reversible and is driven to completion by addition of sulfur trioxide, which converts the water to sulfuric acid. |
| A practical concern in the use of electrophilic aromatic substitution reactions in synthesis is the separation of isomer mixtures. |
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