Substitution

From WikiMD's Food, Medicine & Wellness Encyclopedia

Substitution is a concept in chemistry where one atom, ion, or functional group in a chemical compound is replaced by another. This process can occur in various types of reactions, including nucleophilic substitution, electrophilic substitution, and free radical substitution.

Types of Substitution Reactions[edit | edit source]

Nucleophilic Substitution[edit | edit source]

In a nucleophilic substitution reaction, a nucleophile, an atom or molecule that donates an electron pair, replaces a group in a molecule. There are two main types of nucleophilic substitution reactions: SN1 and SN2.

SN1 Reaction[edit | edit source]

In an SN1 reaction, the leaving group first departs, forming a carbocation, which is then attacked by the nucleophile.

SN2 Reaction[edit | edit source]

In an SN2 reaction, the nucleophile simultaneously attacks the substrate and displaces the leaving group.

Electrophilic Substitution[edit | edit source]

In an electrophilic substitution reaction, an electrophile, an atom or molecule that accepts an electron pair, replaces a group in a molecule. This type of reaction is common in aromatic compounds, such as benzene.

Free Radical Substitution[edit | edit source]

In a free radical substitution reaction, a free radical replaces a group in a molecule. This type of reaction is common in alkanes and alkenes.

See Also[edit | edit source]

Substitution Resources
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