Methylation
Methylation is any chemical reaction that adds a methyl group (−CH3) to a chemical compound. It is a type of addition reaction. Methylation reactions take place between a methylating agent, the source of the methyl group, and a substrate that the methyl group is added to.
Types
[change | change source]Electrophilic methylation
[change | change source]When the methylating agent is an electrophile, the methylation reaction normally uses the SN2 mechanism. The better the leaving group on the methylating agent, the stronger it becomes: iodomethane is a much stronger methylating agent than chloromethane, because iodide is a better leaving group than chloride. Highly electrophilic methylating agents like methyl fluorosulfonate are highly toxic and have lead to deaths in industrial accidents.
Nucleophilic methylation
[change | change source]Organometallic compounds like methyllithium and methylmagnesium chloride are examples of nucleophilic methylating agents. These compounds act as equivalents of the synthon CH−3. Carbonyl compounds are a common substrate for nucleophilic methylation reactions, with the Grignard reaction of methylmagnesium chloride being one example.
