Formylation reaction
![](../I/m/Aldehyde2.png)
The formyl group
A formylation reaction in organic chemistry is the catch-all name for any organic reaction in which an organic compound is functionalized with a formyl group (-CH=O).
Aromatic formylation reactions via electrophilic aromatic substitution include:
- Dimethylformamide and phosphorus oxychloride in the Vilsmeier-Haack reaction
- Hexamine in the Duff reaction and the Sommelet reaction
- Carbon monoxide and hydrochloric acid in the Gattermann-Koch reaction
- Anionic cyanides in the Gattermann reaction. This method synthetizes aromatic aldehydes using hydrogen chloride and hydrogen cyanide (or another metallic cyanide as such zinc cyanide) in the presence of Lewis acid catalysts:
![](../I/m/Gattermann_aldehyde_synthesis.png)
- Chloroform in the Reimer-Tiemann reaction
- dichloromethyl methyl ether in Rieche formylation
In biological systems, formylation is one of the processes of posttranslational modification in which a formyl group is added to the N-terminus of a protein.